October 2021 Archives

Sunday, October 31, 2021

CONTEXT: SCANALYZER Has a New Home

As announced on 2021-10-26, effective today, SCANALYZER has completed its move to the SCANALYST site, which is in full production mode.

All content posted here since 2021-10-04 has been mirrored at SCANALYST, and new content will only be posted there. You can either bookmark the SCANALYST main page, which contains other topics in addition to SCANALYZER, or go directly to the SCANALYZER category page, which will only show you those posts.

SCANALYST is a Discourse discussion forum, in which registered members can comment and create their own posts, but there is no need to join in order to read the SCANALYZER posts just as you've done here. If you do wish to join, SCANALYST has no subscription fees, no advertising, and requires no personal information other than a valid E-mail address to confirm your sign-up. We will never knowingly disclose any personal information about users.

I'll see you at SCANALYST!

Posted at 11:38

Saturday, October 30, 2021

THE HAPPENING WORLD: Breakthrough Listen Candidate Signal Evaluated to be Terrestrial Interference

On 2019-04-29, the Parkes radio telescope in Australia was observing the closest star, Proxima Centauri, to study its flare behaviour. The Breakthrough Listen project was conducting a piggy-back analysis of the signals, filtering for narrow-band emissions which might indicate transmissions from a technological civilisation. A signal was received, persisting for two and a half hours, which passed all of the tests for such a signal:

1. It is a ~Hz-wide narrowband signal, which cannot be created by any known or foreseeable astrophysical system, only by technology.
2. It exhibits a non-zero drift rate, as expected for a transmitter that was not on the surface of the Earth.
3. Its drift rate appears approximately linear in each 30 min ‘panel’ (one single-target observation from a cadence of observations that makes up a waterfall plot), but the drift rate changes smoothly over time, as expected for a transmitter in a rotational/orbital environment.
4. It is absent in the off-source observations (see ‘Initial investigation and parametrization of blc1’), as expected for a signal that is localized on the sky.
5. It persists over several hours, making it unlike other interferers from artificial satellites or aircraft that we have observed before.

The signal was declared a “candidate” by Breakthrough Listen and given the name “blc1” for Breakthrough Listen Candidate 1”. Two papers published in the 2021-10-25 issue of Nature Astronomy:

• “A radio technosignature search towards Proxima Centauri resulting in a signal of interest”
• “Analysis of the Breakthrough Listen signal of interest blc1 with a technosignature verification framework”

have now concluded that the signal was likely terrestrial interference. From the abstract of the second paper:

… [W]e find that blc1 is not an extraterrestrial technosignature, but rather an electronically drifting intermodulation product of local, time-varying interferers aligned with the observing cadence. We find dozens of instances of radio interference with similar morphologies to blc1 at frequencies harmonically related to common clock oscillators.

A popular “front of book” article in the same issue with the somewhat sensational title “Mysterious ‘alien beacon’ was false alarm” summarises the results. The actual source of the signal has not been identified, and the signal has never been observed since.

Here is an interview with Shane Smith, the Hillsdale College undergraduate intern at the Berkeley SETI project, who discovered the signal in the Parkes data.

Posted at 13:43

CONTEXT: From 1970—IBM System/370 Product Announcements

The IBM System/370 was announced in June 1970 as the replacement for its extremely successful System/360 range of mainframes. It was 100% upward compatible with System/360, running the same operating systems and application programs and supporting the same peripherals, and thus provided an easy migration path for System/360 customers. It replaced the “solid logic” circuitry used in the 360 with monolithic integrated circuits, and the 370/145 and all subsequent models replaced core memory with semiconductor main memory.

When the System/370 was announced, many observers were surprised it did not include virtual memory, which was all the rage in computer architecture at the time, and which IBM had previously introduced in the System/360 model 67 in 1965. In 1972, the original System/370 models 155 and 165 were replaced by the 158 and 168 which did support virtual memory, as did all subsequent models in the series. The System/370 would continue to be marketed for twenty years until replaced by the System/390, with numerous evolutionary changes in the architecture over time.

The IBM 3211 printer shown in the final film was stunning. Nobody made printers like IBM—this beast would crank out 2000 lines per minute, day and night, box after box of paper, without a hiccup.

Posted at 13:00

TRACKING WITH CLOSEUPS: Exploring Ant Nest Architecture with Molten Metal

Prof. Walter Tschinkel's book, Ant Architecture: The Wonder, Beauty, and Science of Underground Nests, published in June 2021, describes the techniques he has developed for casting ant nests and what he has learned about the various ways ants structure their subterranean habitats.

Posted at 12:21

CONTINUITY: KIC 8462852 (Boyajian's Star): Possible Periodicity?

The mystery star KIC 8462852, “Tabby's Star”, which the Kepler spacecraft observed to exhibit stunning (up to 22%) and irregular dimming events, continues to defy explanation. In 2017, Gary Sacco and two co-authors reported “A 1574-day periodicity of transits orbiting KIC 8462852”. The period has come around again, and current observations indicate the dips have returned, but not as deep as observed by Kepler. Images of the star have been found on archival plates exposed in 1978 and 1935 showing dimming consistent with the periodicity. In this interview, Gary Sacco provides an update on the current observing season, the archive discoveries, and speculations on the cause of the dimming events.

Posted at 11:41

Friday, October 29, 2021

CONTINUITY: “Spot Me Up”

Posted at 12:15

THE HAPPENING WORLD: Boeing Takes Another US$ 185 Million Charge on “Hangar Queen” Starliner

Boeing said Wednesday it will take on a $185 million charge in its third quarter earnings to pay for the latest setback on the Starliner crew capsule, bringing the company's out-of-pocket costs on the troubled program to $595 million since 2019. https://t.co/TdSqVw9Gmd pic.twitter.com/WF8yhZnEpA

— Spaceflight Now (@SpaceflightNow) October 29, 2021

Posted at 11:48

CONTINUITY: Mark Zuckerberg on the Metaverse

At Facebook Connect, Mark Zuckerberg announced the renaming of the Facebook parent company as “Meta” and his vision for the “Metaverse”, a term coined by Neal Stephenson in his 1992 science fiction novel Snow Crash. CNET has assembled a compilation of various segments describing how a mature system might look.

This is a different compilation, with some duplication, that discusses the name change and goes into more detail about human interface device development.

What is missing from Zuckerberg's “vision”. Well, his “metaverse” doesn't seem to have the ubiquitous, intrusive, and unavoidable advertising which pollute all of his other platforms—what do you think the odds are it won't be even more horrific in an immersive three-dimensional virtual world. And then there's the snooping, data-mining, censorship, indoctrination, and cancellation of people for wrong-think. Just imagine how much more power the operators of the metaverse will have when they can ban individuals or organisations from this unified means of social interaction and commerce. I'll bet the reality looks more like that imagined by Keiichi Matsuda in his short film “Hyper-Reality”, which I featured here back on 2021-10-01, but is worth another view in the context of the Facebook/Meta announcement.

It has been thirty-three years since my 1988 paper, “Through the Looking Glass: Beyond ‘User Interfaces’ ”.

Posted at 11:12

THE HAPPENING WORLD: X1-Class Solar Flare—Coronal Mass Ejection Heading for Earth

A Direct Hit for #Halloween! The #solarstorm launched during the X-flare today is indeed Earth-directed! NASA predictions confirm impact by early October 31. Expect #aurora to mid-latitudes, as well as #GPS reception issues and #amateur radio disruptions on Earth's nightside! pic.twitter.com/Jjk3eixWIq

— Dr. Tamitha Skov (@TamithaSkov) October 28, 2021

Here is more on the event and predictions for its consequences at spaceweather.com.

Posted at 10:23

TRACKING WITH CLOSEUPS: Supersonic Baseball: 1, Mayonnaise Jar: 0

Posted at 10:15

Thursday, October 28, 2021

THE HAPPENING WORLD: Intel 12th Generation “Alder Lake” i9-12900K Processor—Press Kit and a Look Inside

Intel's 12th generation CPUs, code named “Alder Lake” is scheduled to launch on November 4th, 2021. Here is a description of the chips and rumoured specifications.

Chips and compatible motherboards and memory are already in the hands of the trade press, with reviews expected to drop as soon as the embargo lifts on November 4th. Ian Cutress is one of those reviewers, and provides a look inside Intel and MSI's press kits sent to reviewers.

German extreme overclocker and YouTuber “der8auer” is also reviewing the chip and managed, by a fat finger, to blow up his i9-12900K CPU. He took the opportunity to remove the lid and take a look inside, evaluating the physical construction of the packaging and its suitability for direct die cooling for power-mad overclockers.

And, by the way, if you think overclocking is some kind of outré activity undertaken by gamers with an excess of time on their hands and a shortage of common sense, did you know that Intel publishes a document titled “How to Overclock Your Unlocked Intel® Core™ Processor” and even provides a free “Extreme Tuning Utility” to aid in the process?

Posted at 13:58

CONTEXT: Dinosaurs—The True Story

How's that space program coming along?

Posted at 13:05

TRACKING WITH CLOSEUPS: An Appreciation of Pure LISP

John McCarthy's 1960 paper, “Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I” [PDF, reproduction of original], which introduced the LISP programming system, was a stunning achievement in the history of computing. McCarthy proved that with only a minimal set of functions and linked lists, it was not only possible to evaluate any computable function (Turing completeness), but that there was no distinction between programs and data—programs could manipulate themselves as easily as they could items of data. In a sense,a large part of the history of programming languages in the six decades that followed was re-inventing concepts inherent in Lisp from its origin.

In this talk from 2019 Linux conference, Kristoffer Gronlund describes LISP, demonstrates how so few primitives can have such power, and describes how it has influenced programming languages and how we think about computing over the years.

Posted at 12:33

CONTEXT: Florida Man—NASA Administrator Clarence William Nelson on UFOs

This is an excerpt from an hour long interview on 2021-10-19 at the University of Virginia Center for Politics. Scroll back to the beginning if you wish (why?) to see the whole thing.

The interviewer/host, Larry Sabato, Director of the Center for Politics, is also a prize: “Of course, Einstein believed in parallel universes. So, that's good enough for me, if Einstein believed in it, and he inspired a lot of Rod Serling's ‘Twilight Zone’s” [56:50].

Posted at 11:26

CONTINUITY: A Dyson Sphere May Double the Lifetime of a Low Mass Star

Warning: some assembly required - Huston @macyjhuston and @Astro_Wright on "Evolutionary and Observational Consequences of Dyson Sphere Feedback" showing how Dyson Spheres can double the main sequence lifetime of low mass (convective) stars!
https://t.co/jw255xoTMv pic.twitter.com/X5TiLAxRrP

— Matthew Kenworthy (@mattkenworthy) October 27, 2021

Here is the full paper, “Evolutionary and Observational Consequences of Dyson Sphere Feedback” [PDF].

Posted at 10:46

Wednesday, October 27, 2021

TRACKING WITH CLOSEUPS: Starship Mars Missions Before Refuelling on Mars

SpaceX's plans for an Earth-Mars transportation infrastructure assume the ability to refuel Starships on Mars with methane and oxygen propellant manufactured from resources on Mars (carbon dioxide and water, plus electricity generated from solar or nuclear power), a process called “in-situ resource utilisation” (ISRU). But first the propellant plant has to be delivered to Mars, so initial Starship missions will necessarily be one-way, at least until the plant they deliver has produced sufficient fuel to permit them to return. Marcus House looks at the logistics of this, including the mass budget for a solar powered propellant plant.

Posted at 13:22

CONTEXT: How Virtual Worlds Work—Part 5, Ownership of Virtual Objects

We’ve talked in depth about virtual spaces and digital objects, but who owns them? https://t.co/NqjIMxOa8W#NFT #Ownership #Metaverse pic.twitter.com/BqGrMyAdUq

— Playable Worlds (@PlayableWorlds) October 21, 2021

Posted at 12:55

CONTINUITY: Avi Loeb: “Was Our Universe Created in a Laboratory?”

In his 1999 book, The Life of the Cosmos, Lee Smolin suggested that the reason the universe appeared to be so fine-tuned for complexity and life was what he termed “cosmic natural selection”, in which new baby universes were born during the formation of black holes, each with physical properties that differed from their parent universe due to quantum uncertainty. Universes in which, for example, star formation was impossible would have no progeny and die out, and those that collapse to a single black hole would create only one child universe. Only those in which the initial conditions allowed the formation of massive stars would produce a multitude of black holes, and these would come to dominate the population of universes. But the massive stars that end up as black holes are the prerequisite for creating the heavy elements which are necessary to form planets and living beings. So, we shouldn't be surprised to find ourselves in a universe which appears to have been fine tuned to create the requirements for our form of life.

Now, Harvard astronomy professor Avi Loeb proposes an even more breathtaking speculation in a Scientific American opinion piece, “Was Our Universe Created in a Laboratory?”. Loeb argues that an advanced technological civilisation, which he calls “Class A”, will eventually develop the capability, perhaps by manipulating dark matter and dark energy, or via some means we haven't yet imagined, to perform the ultimate experiment—creating baby universes. If they can control the physical parameters of these universes, they would naturally fine tune them so they would, in turn, eventually produce their own Class A inhabitants. The process of natural selection would, then, operate on the scale of the multiverse, with universes that never produce a Class A civilisation producing no progeny, while those that eventually evolve Class A civilisations are fruitful and proliferate.

Loeb considers humanity at present a Class C civilisation, as we are unable to re-create a habitat for ourselves when the Sun dies. “A class B civilization could adjust the conditions in its immediate environment to be independent of its host star. A civilization ranked class A could recreate the cosmic conditions that gave rise to its existence, namely produce a baby universe in a laboratory.”

Posted at 11:28

CONTEXT: Albert Einstein and his Flying Car

This sequence was filmed on the Warner Brothers special effects stage at Warner Brothers in Los Angeles during a Einstein's visit to California in 1931. It has been colourised and re-processed to 4K, 60 frames per second video.

Einstein was not only a film star, but also an inventor. Just a few months earlier, he and Leo Szilard were granted U.S. patent 1,781,541 for the Einstein-Szilard Refrigerator.

Posted at 10:43

Tuesday, October 26, 2021

THE HAPPENING WORLD: SCANALYZER Is Moving to SCANALYST

SCANALYZER is moving. After 2021-10-31 (Hallowe'en!), SCANALYZER is moving to the new SCANALYST site, a Discourse-based discussion forum which will publish all of the current content from SCANALYZER and allow members to comment, discuss, and write their own posts on any topic that interests them.

All content posted at SCANALYZER since 2021-10-04 has been mirrored at SCANALYST, so if you follow this site, just change your bookmark to read all of the same content and more there. If you like what you see, sign up to comment and share your own posts with a like-minded community. SCANALYST has no subscription fees, no advertising, and requires no personal information other than a valid E-mail address to confirm your sign-up. We will never knowingly disclose any personal information about users. Almost all posts at SCANALYST, and every one in the SCANALYZER categories, are readable regardless of whether you sign up or not. If you sign up, you can comment and write your own posts.

SCANALYST is a forum for civilised conversation. Other than momentary lapses of reason, disruptive or abusive behaviour will result in immediate exclusion from commenting or posting at the site without possibility of appeal. There's already too much coarseness in today's world: we don't need any more.

If this sounds like something in which you'd like to participate, just visit the site, click “Sign Up” at the top right, and jump in.

I hope to welcome many readers of this site to SCANALYST.

Posted at 13:27

CONTINUITY: June 1940—When France Bombed Berlin

The raid, conducted by the French Navy, was led by Henri Daillière. It was the first bombing of Berlin—the British RAF did not strike Berlin before August 25, 1940, by which time France was out of the war. Here is more about the Daillière attack on Berlin.

Posted at 13:02

TRACKING WITH CLOSEUPS: Origins of Photography: From Daguerrotype to Roll Film

Posted at 12:55

CONTINUITY: How Did Apollo Send Live Television from the Moon?

This video focuses on the spacecraft television cameras and ground receiving and conversion gear. The actual transmission of the signal was described in earlier posts about the Apollo Spacecraft S Band Communication System: Part 1, Part 2.

Posted at 12:16

CONTEXT: “Orbital Reef”—Commercial Space Station

Announcing #OrbitalReef - a commercial space station transforming human space travel and opening access to new markets. Our team developing the premier commercial destination in low Earth orbit: @BlueOrigin @SierraSpaceCo @BoeingSpace @RedwireSpace @ASU https://t.co/PP4wxrfkF3 pic.twitter.com/qJDdYg7BSv

— Orbital Reef (@OrbitalReef) October 25, 2021

The “team” is led by Blue Origin, founded 21 years ago, and Sierra Space, which acquired the Dream Chaser spacecraft, which was announced in 2004, 17 years ago. Neither has, to this date, attempted or completed an orbital flight. Team members include Boeing, the launch of whose Starliner “Hangar Queen” is slipping further into 2022 due to problems with hypergolic reaction control thrusters, a technology dating from the 1950s. What could possibly go wrong?

Posted at 11:50

Monday, October 25, 2021

TRACKING WITH CLOSEUPS: Flying Ants in Slow Motion

These male (drone) ants are of genus Odontomachus (trap-jaw) and Aphaenogaster and were recorded taking off and flying at 1500 and 3200 frames per second,

Posted at 14:23

TRACKING WITH CLOSEUPS: Investigating the Apple M1 Pro and Max Chips in Detail

After last week's launch of the new MacBook Pro's with the new M1 Pro and M1 Max Apple Silicon chips, we've had our hands on the new SoCs, testing out the 10-core CPU, 32-core GPU, and the tremendous memory performance of the new designs:https://t.co/jGHmhWB9AQ pic.twitter.com/bODydDHnyg

— AnandTech (@anandtech) October 25, 2021

Here is the full AnandTech article, without clicky-breaks between sections, “Apple's M1 Pro, M1 Max SoCs Investigated”.

Posted at 13:17

CONTEXT: The Curious World of Radio Pulsars

Posted at 12:45

CONTINUITY: South Korea’s Long Road Toward a Domestic Space Launch Industry

Posted at 11:50

Sunday, October 24, 2021

TRACKING WITH CLOSEUPS: Blue Field Entoptic Phenomenon—Seeing Blood Cells in the Retina

The really remarkable thing about the blue field entoptic phenomenon isn't that you can see the red blood cells moving, but that you don't see the blood vessels and blood in front of the retina all the time. This is the brain up to its old trick of “editing out” distracting information.

Posted at 14:38

CONTINUITY: ARM1 from 1985 vs. Apple M1 Max

Here are the two dies at the same scale. The M1 Max is much larger physically; I estimate it is 20 mm wide. Its transistors are much smaller (5 nm vs 3000 nm) giving it 57 billion transistors instead of 25,000. If built with modern transistors, the ARM1 would be a tiny dot. pic.twitter.com/OdLhG7TXX2

— Ken Shirriff (@kenshirriff) October 18, 2021

Here is more about the evolution of the ARM processor architecture over the years.

Posted at 12:38

CONTEXT: Earth and Moon from the Lunar South Pole

This computer-generated animation shows the Earth and Moon as viewed from the rim of Shackleton crater near the Moon's south pole, with the camera aimed at the mean position of the Earth. The Sun circles the horizon once a month, never more than 1.5 degrees above or below the horizon. The Earth bobs around its mean position with the lunar librations due to the eccentricity and inclination of the Moon's orbit. Shackleton crater is deep, 4.2 km, and in perpetual shadow. It is believed that water and other volatiles may have collected there.

Posted at 11:58

THE HAPPENING WORLD: Weekly Space Report: Starship Static Fires, Catcher Arms Installed on Tower, NASA SLS Stacking Complete

Posted at 11:10

Saturday, October 23, 2021

TRACKING WITH CLOSEUPS: Collecting and Curating Crayfish in Carolina

Posted at 12:52

CONTEXT: AutoCAD Release 10 on an IBM Professional Graphics Controller

here's AutoCAD release 10 running on the IBM PGC! pic.twitter.com/gyFMgBc1S4

— Tube🎃Time (@TubeTimeUS) October 17, 2021

The IBM Professional Graphics Controller (PGC) (which was often incorrectly called a PGA, for Professional Graphics Adapter, by many people, including me) was a remarkable device for its time. Introduced in 1984, around the same time as the PC/AT, it was compatible with both the original IBM PC and XT as well as the AT. It supported 640×480 pixel 60 Hz graphics with a 256 colour palette of 8-bit RGB values and had 320 kB of on-board display memory, so it occupied none of the scarce 640 kB address space of the PC architecture. It had its own Intel 8088 microprocessor (the same as in the PC and XT) which implemented high-level graphics commands such as drawing arcs and circles and solid filling polygons. This allowed AutoCAD to offload all of the pixel-pushing to the graphics board, speeding up image regeneration.

This power came a a price—a forbidding one. List price for the PGC, which consisted of three printed circuit boards stacked together, was US$ 4,290 in 1985, which is equivalent to US$ 11,000 in today's BidenBucks. This was comparable to the price of an entire IBM PC/XT, which was US$ 4,995 in 1985. This thing was so expensive that I doubt Autodesk would have bought one to support it if IBM hadn't loaned us one to develop a driver. After developing an AutoCAD driver for it (which was a breeze thanks to the on-board graphics primitives), I later used the board in the development of AutoShade, as it was one of the few 256 colour boards available at the time.

Here is a long Twitter Thread from Tube Time (scroll back to the start), who recently restored an IBM PC/AT which probably belonged to an AutoCAD customer back in the day and got AutoCAD Release 10 (which shipped in October 1988) running on it.

Posted at 11:57

CONTINUITY: The Amazing Tracking Shot from Soy Cuba

Soy Cuba (I Am Cuba) is a 1964 film by directed by Mikhail Kalatozov of the Mosfilm studio in the Soviet Union. The film, an anthology of four stories intended to show how horrible life was in pre-revolutionary Cuba, was poorly received at the time and little known until it was rediscovered by Martin Scorsese and others in the 1990s, who were stunned by the cinematography, particularly the long tracking shot in the funeral scene which starts at the 1:43 point in this clip. Wikipedia describes the shot as follows.

In another scene, the camera follows a flag over a body, held high on a stretcher, along a crowded street. Then it stops and slowly moves upwards for at least four storeys until it is filming the flagged body from above a building. Without stopping, it then starts tracking sideways and enters through a window into a cigar factory, then goes straight towards a rear window where the cigar workers are watching the procession. The camera finally passes through the window and appears to float along over the middle of the street between the buildings. These shots were accomplished by the camera operator having the camera attached to his vest—like an early, crude version of a Steadicam—and the camera operator also wearing a vest with hooks on the back. An assembly line of technicians would hook and unhook the operator's vest to various pulleys and cables that spanned floors and building roof tops.

Posted at 11:29

TRACKING WITH CLOSEUPS: What Is This? Exploring a Mystery Hewlett-Packard Instrument From 1950

I was about to call this an “early Hewlett-Packard product”, but that wouldn't be correct. Hewlett-Packard was founded in 1939 and by 1943 already employed 200 people manufacturing a line of electronic test equipment sold to industry and the military. This indisputably is, however, an odd Hewlett-Packard product.

Posted at 10:44

Friday, October 22, 2021

TRACKING WITH CLOSEUPS: Piranha Solution

A mixture of around 3/4 concentrated sulfuric acid and 1/4 hydrogen peroxide (don't add too much peroxide or it may explode, which would be bad) is called “piranha solution”. It does the most remarkable things to organic material. It is used in semiconductor manufacturing to remove photoresist from silicon wafers.

Posted at 13:07

CONTINUITY: Lunar Worm

Before the Surveyor spacecraft landed on the Moon, nothing was known about the properties of its surface. Some very odd ideas were explored about how one might move around there.

Posted at 12:08

CONTEXT: How Virtual Worlds Work—Part 4, Objects and Behaviours

🤔What goes into making a digital object function?

Turns out, it’s not as simple as we may think - Raph goes into all the details in his latest article here: https://t.co/wpInAsbBZK#GameDev #MMORPG pic.twitter.com/eETMeUX7RA

— Playable Worlds (@PlayableWorlds) October 14, 2021

Posted at 11:38

TRACKING WITH CLOSEUPS: Embryonic Development of the Alpine Newt

Posted at 11:08

Thursday, October 21, 2021

CONTINUITY: From 1947—Office Automation Before the Computer

Posted at 13:28

CONTINUITY: The Case for Anarchy with Michael Malice and Glenn Beck

Michael Malice's book, The Anarchist Handbook, is a collection of classic works on anarchism by authors including Proudhon, Bakunin, Spooner, Kropotkin, and Rothbard.

Posted at 12:55

CONTEXT: Ducks in a Row

Simulations reveal that ducklings swimming in a single-file formation behind the parent can achieve a wave-riding benefit whereby the wave drag turns positive. Gives a new meaning to "get your ducks in a row" 🦆@JFluidMech #dynamic #equilibrium #swimming https://t.co/HUmZXhhCcV pic.twitter.com/RxNBEXBQjc

— Journal of Fluid Mechanics (@JFluidMech) October 19, 2021

The full paper is “Wave-riding and wave-passing by ducklings in formation swimming”.

Posted at 12:13

CONTINUITY: Ariane 6 Launch Complex

The first flight of Ariane 6 is now expected to be in late 2022. Cost per launch is estimated at €75 million for the two solid booster version (10.35 tonnes to low Earth orbit [LEO]) and €115 million for four solid boosters (21.65 tonnes to LEO). By comparison, the SpaceX Falcon 9 costs around US$ 50 million (~ €43 million) for a launch with recovery of the first stage, with payload of 15.6 tonnes to LEO.

Posted at 11:49

Wednesday, October 20, 2021

THE HAPPENING WORLD: Announcing: Fourmilab Blockchain Tools

Fourmilab Blockchain Tools provide a variety of utilities for users, experimenters, and researchers working with blockchain-based cryptocurrencies such as Bitcoin and Ethereum. These are divided into two main categories.

Bitcoin and Ethereum Address Tools

These programs assist in generating, analysing, archiving, protecting, and monitoring addresses on the Bitcoin and Ethereum blockchains. They do not require you run a local node or maintain a copy of the blockchain, and all security-related functions may be performed on an “air-gapped” machine with no connection to the Internet or any other computer.

• Blockchain Address Generator creates address and private key pairs for both the Bitcoin and Ethereum blockchains, supporting a variety of random generators, address types, and output formats.

• Multiple Key Manager allows you to split the secret keys associated with addresses into n multiple parts, from which any k ≤ n can be used to reconstruct the original key, allowing a variety of secure custodial strategies.

• Paper Wallet Utilities includes a Paper Wallet Generator which transforms a list of addresses and private keys generated by the Blockchain Address Generator or parts of keys produced by the Multiple Key Manager into a HTML file which may be printed for off-line “cold storage”, and a Cold Storage Wallet Validator that provides independent verification of the correctness of off-line copies of addresses and keys.

• Cold Storage Monitor connects to free blockchain query services to allow periodic monitoring of a list of cold storage addresses to detect unauthorised transactions which may indicate they have been compromised.

Bitcoin Blockchain Analysis Tools

This collection of tools allows various kinds of monitoring and analysis of the Bitcoin blockchain. They do not support Ethereum. These programs are intended for advanced, technically-oriented users who run their own full Bitcoin Core node on a local computer. Note that anybody can run a Bitcoin node as long as they have a computer with the modest CPU and memory capacity required, plus the very large (and inexorably growing) file storage capacity to archive the entire Bitcoin blockchain. You can run a Bitcoin node without being a “miner”, nor need you expose your computer to external accesses from other nodes unless you so wish.

These tools are all read-only monitoring and analysis utilities. They do not generate transactions of any kind, nor do they require unlocked access to the node owner's wallet.

• Address Watch monitors the Bitcoin blockchain and reports any transactions which reference addresses on a “watch list”, either deposits to the address or spending of funds from it. The program may also be used to watch activity on the blockchain, reporting statistics on blocks as they are mined and published.

• Confirmation Watch examines blocks as they are mined and reports confirmations for a transaction as they arrive.

• Transaction Fee Watch analyses the transaction fees paid to include transactions in blocks and the reward to miners and produces real-time statistics and log files which may be used to analyse transaction fees over time.

Details

You can download the complete source code distribution, including ready-to-run versions of all of the programs, from the Fourmilab Blockchain Tools home page.

All of this software is licensed under the Creative Commons Attribution-ShareAlike license.

Please see the Fourmilab Blockchain Tools User Guide [PDF] for details or read the complete source code [PDF] in Perl and Python written using the Literate Programming methodology with the nuweb system.

Posted at 15:20

CONTEXT: Boeing's Starliner Is a Mess—But What Were the Alternatives?

Posted at 14:19

CONTINUITY: The WiFi Hidden Node Problem

Here is an explanation of the hidden node problem and how the IEEE 802.11 RTS/CTS mechanism avoids most collisions on carrier-sense multiple access with collision avoidance (CSMA/CA) wireless networks.

Posted at 13:55

TRACKING WITH CLOSEUPS: James Webb Space Telescope Deployment—“29 Days on the Edge”

Here are some statistics to ponder:

• 50 major deployment events
• 178 release mechanisms
• 300 single-point failure items
• Sun shield:
  • 140 release mechanisms
  • 70 hinge assemblies
  • 8 deployment motors
  • 400 pullies
  • 90 cables, totalling 400 metres in length

All of this has to work, or the James Webb Space Telescope, which has been under development for 25 years and cost US$10 billion, will be space junk. Positioned in an Earth-Sun L2 halo orbit, no repair mission will be possible.

Posted at 13:25

CONTINUITY: NASA's Ambitious Original Plans for Apollo

With the exception of Skylab, all of these plans came to naught as the NASA budget was cut to fund the Vietnam war and “Great Society” welfare programs. Yes, the manned Venus fly-by concept was really a thing: here is the 1967 study of such a mission by NASA contractor Bellcomm. Gerald Brennan's Island of Clouds is a fictional account of that mission.

Posted at 12:16

Tuesday, October 19, 2021

TRACKING WITH CLOSEUPS: Morley Cigarettes and More—Hollywood's Fake Brands

Posted at 12:59

CONTINUITY: The Swiss Rifle Range That Shoots Over a Busy Highway

Here is the stand de tir in my village. We have the same microphone-based target scoring system.

Posted at 12:43

CONTEXT: David Friedman and James Bennett on Property Rights in Space

Posted at 11:30

THE HAPPENING WORLD: SpaceX Starship SN 20 Pre-Burner Test

This appears to have been a single engine pre-burner test of Raptor vacuum engine number 5. The pre-burner powers the turbopumps that force fuel and oxidiser into the combustion chamber. In a pre-burner test, the main combustion chamber is not ignited. This is a normal step on the way to a full thrust static firing.

Posted at 11:09

Monday, October 18, 2021

CONTINUITY: 1915 Vintage Western Electric “Candlestick” Phone

The classic Western Electric #20B candlestick telephone was patented in 1904 and remained in production until the 1920s, when it was supplanted by desktop phones with the transmitter and receiver in one handset. The candlestick phone contained no ringer, and was connected to a separate “subscriber set” or ringer box containing the bells. Later models for automatic exchanges added a rotary dial in the base. Many candlestick phones remained in service, leased and maintained by telephone companies, until the 1940s and '50s. They are electrically compatible with today's wired telephone networks.

The earpiece that hung on the hook was called the “receiver”, and the phone was answered by picking it up. A remnant of this remains in the English language, with many people continuing to call the handset of modern telephones “the receiver”. In French, the handset is called «le combiné», indicating it contains both the microphone and receiver.

Posted at 13:55

CONTINUITY: Fat Finger—More Than 12,000 Ethereum Lost to Typos

Unlike Bitcoin public addresses, which incorporate a 32 bit checksum, the original specification for Ethereum public addresses was simply strings of 40 hexadecimal digits, for example 0xc9b83ab54c84aac4445b56a63033db3d5b017764. If somebody attempts to send funds to such an address and accidentally mistypes or transposes even a single digit of the address, the funds will be sent to an address whose private key is unknown and which is computationally intractable to discover (there are 16⁴⁰≈10⁴⁸ possible Ethereum addresses) and thus lost forever. Obviously, it is a poor idea to type in such an address, and errors in optical scanning, text editors, and cut and paste mechanisms all pose risks of error.

In 2018, Johannes Pfeffer decided to estimate the quantity of Ether (the name for the currency of the Ethereum system) lost by having been sent to mistyped addresses. The methodology was clever and simple: search the blockchain for pairs of addresses, both of which had received funds, but which differed only by one character. An address of such a pair which had no outgoing transactions was almost certainly a typographical error entering the other, because the probability of two such similar addresses being generated from independent known private keys is comparable to that of guessing the private key from a public address. He reported the results in “Over 12,000 Ether Are Lost Forever Due to Typos”.

As of the date of his study, 2,674 typos were found, affecting 2,053 accounts, with total funds lost amounting to ETH 12,622, which at this writing has a value in excess of US$ 47 million (when he did his study, it was “only” US$ 8.84 million). All of these funds have gone to the great bit bucket in the sky, never to be seen again.

It's odd that Ethereum addresses weren't designed from the outset to incorporate a checksum, especially since International Bank Account Numbers (IBAN) and Bitcoin addresses which pre-date Ethereum both include checksums. The reasoning appears to have been that the hexadecimal addresses would not be directly used by humans, but rather encoded forms such as the IBAN-compatible ICAP or through a domain name like system such as now exists with the Ethereum Name Service. But, in fact, Ethereum wallets and individuals went ahead and used the hexadecimal addresses without checksums, and the consequences were predictable.

In 2016, this situation became sufficiently embarrassing that Ethereum Improvement Proposal EIP-55, “Mixed-case checksum address encoding” specified a checksum of sorts, in which a hash of the original address is encoded in hexadecimal digits between “A” and “F” by writing them in upper or lower case letters. This provides an average of 15 check bits per address, which reduces the probability of an error not being detected to 0.0247%, which is around fifty times better than the two digit IBAN checksum. Almost all Ethereum clients now express addresses in this form and check any submitted address which contains mixed case hexadecimal digits. For compatibility, however, un-checksummed addresses with uniform case hexadecimal digits continue to be accepted.

It would be interesting to repeat the typo analysis and see what effect the introduction and widespread use of checksummed addresses has had on the rate and magnitude of losses to typos.

Posted at 12:00

CONTEXT: Magnetic Mysteries—The “Simple Magnetic Over-Unity Toy”

Ignoring potential energy is the source of much confusion and “inspiration” to designers of perpetual motion machines of the first kind. Simple experiments with magnets demonstrate how confusing and deceptive it can be when all energy flows are not accounted for. Fortunately, physicists, engineers, and patent examiners have learned to approach claims of “over unity” (something for nothing) with extreme scepticism. Now if we could just get the economists and politicians on board.

Posted at 11:32

TRACKING WITH CLOSEUPS: A Monolithic Schmidt-Cassegrain Telescope

A Schmidt-Cassegrain telescope has multiple optical elements: a spherical primary mirror, a hyperbolic secondary mirror, a Schmidt corrector plate (aspheric lens), and sometimes a field flattener lens to create a planar image. Could you make all of these out of one solid piece of glass?

Posted at 11:19

Sunday, October 17, 2021

CONTINUITY: On the Road with Tesla “Full Self Driving” Beta 10.2

Posted at 13:46

CONTEXT: Melting Nuclear Waste to the Earth's Mantle

Now's a good time to plug an awesome proposal for disposing of nuclear waste: literally, put it inside of a big tungsten ball.

The waste heats the ball from the inside, the ball melts the ground underneath it and slowly sinks to the earth's core.https://t.co/scJD2KAljs

— Arthur B. 🌮 (@ArthurB) October 15, 2021

Here is the 2011 paper, “Self-Sinking Capsules to Investigate Earth’s Interior and Dispose of Radioactive Waste”. Full text is available at the ResearchGate site. The first paragraph of the paper is:

Technical experts, science fiction writers, and environmental advocates have all famously considered a self-descending spherical body in a melting environment not as a solution but as a problem. In connection with nuclear reactor core meltdown, this phenomenon is the so-called China Syndrome. Let’s step back and consider the China Syndrome as a solution.

Posted at 12:20

TRACKING WITH CLOSEUPS: Orbiting Nothing—Lagrange Points and Halo Orbits

Posted at 12:14

THE HAPPENING WORLD: Weekly Space Report: Mechazilla Rising, NASA to Monitor Starship Re-entry, Relativity Space 3D Printed Launcher

Posted at 11:38

Saturday, October 16, 2021

THE HAPPENING WORLD: Rwanda Files to Operate 327,320 Satellite Constellation

This filing seems likely to be a 'let's establish that not all of LEO gets owned by the Americans' ploy. But it will be interesting to see how it plays out. The ITU filing is https://t.co/BtYYovpg2q

— Jonathan McDowell (@planet4589) October 15, 2021

Satellite Network Filing RRW2021-42537 was received on 2021-09-21 for the “CINNAMON-937” constellation, which is described in the supplementary notes [PDF] as:

An orbital shell is here defined as the set of orbits with the same inclination. There are 27 of such orbital shells. Each orbital shell, except the equatorial shell made of one single plane, has a total of 12,960 satellites. The 27 orbital shells comprise of 327,320 satellites.

Satellites are to orbit at altitudes between 550 and 643.6 km in shells arranged by inclination,

Posted at 13:49

CONTINUITY: The Sound of Sorting: Fifteen Algorithms in Six Minutes

Sorting items into order is an important task in computing, and a great deal of intellectual effort has been put into studying various techniques optimised for different circumstances. For example, sorting a small collection of objects that fit into memory is one thing, while a huge database that spans multiple removable storage media is entirely another. An algorithm that works well for data that's initially in completely random order may not be the best for data which is mostly already sorted. Donald Knuth wrote an 800 page book on Sorting and Searching, and new work on the topic is published every year.

This video visualises the behaviour of fifteen different sorting algorithms, ranging from very good to horrific (“bogosort”), each operating on a set of random integers with a size adapted to the efficiency of the algorithm. Here is background on how the video was made. A YouTube playlist of additional sorting algorithms is available.

Posted at 13:19

THE HAPPENING WORLD: Top Ten Assets by Market Capitalisation

The Infinite Market Cap Web site ranks more than 13,000 assets by market capitalisation, which is defined for various assets as follows.

• For precious metals the Market Cap is calculated by multiplying the its price with an estimation of the quantity of metal that has been mined so far. These estimations are updated annually.
• For stocks it is calculated by multiplying the amount of outstanding shares with the current share price.
• The Market Cap of cryptocurrencies is calculated by multiplying the circulating supply with the coin's price.

One can quibble with these definitions: for example, silver, ranked as the 7th largest asset, is an industrial metal which is consumed in many of its applications, so there is a large gap between the total amount mined over history and the existing above-ground supply. For cryptocurrencies, estimates are based upon circulating supply in public hands, excluding funds believed to be lost, some of which might reappear in the future. Obviously, all of these asset prices are volatile and this ranking represents their valuation as of the date of this post.

A few observations: it is stunning to observe that, among companies in the top ten, only Saudi Aramco is not a technology company, and is the only one founded prior to 1975. We often think of Big Oil and Big Banking as archetypes of corporate wealth and power, but only one oil company and no bank made the top ten. The highest ranked bank, JPMorgan Chase, came in at 16th, just before the Ethereum cryptocurrency at 17th. The largest traditional industrial company (but with a strong presence in technology as well) was Samsung at 22, and brick and mortar retailing leader Walmart ranked 23.

The total valuation of the top ten assets combined was US$ 25.7 trillion, which is less than the U.S. national debt of US$ 28 trillion and change.

Autodesk ranks number 306, with market cap US$ 64 billion, beating out Northrop Grumman at 307 and US$ 63.3 billion and Ford Motor Company in 312th place at US$ 62.7 billion. Also in the cheap seats are Federal Express (322), UBS (324), General Dynamics (341), and Honda (381).

Dogecoin is hanging in there at 705th with market cap US$ 31.5 billion.

Posted at 12:15

CONTEXT: A Zoologist Contemplates Alien Life

Might convergent evolution and the limited number of biomechanical solutions to the needs of life result in alien life being no more weird than what we find on Earth? (Although if you look at some of the critters that inhabit the ocean, that's already pretty weird.) Dr Kershenbaum's book is The Zoologist's Guide to the Galaxy.

Posted at 11:14

Friday, October 15, 2021

THE HAPPENING WORLD: Shenzhou-13 Crew Launch to Chinese Tiangong Space Station

Shenzhou-13 launch is scheduled for 16:23 UTC on 2021-10-15. The launch is to carry a crew of three to the Tiangong space station for a planned six-month stay.

Posted at 14:11

TRACKING WITH CLOSEUPS: Prelude FLNG—600,000 Tonne Floating Liquefied Natural Gas Plant

Here is more about Prelude FLNG. It is 488 metres long, 74 metres high, and rises 105 metres above the water line. Unpowered, it is towed into position by oceangoing tugboats, then tethered to the sea floor by chains and connected to well head equipment by flexible pipes. It is designed to be able to ride out a category 5 cyclone, and has the ability to “weathervane” into the wind.

Posted at 12:47

CONTEXT: The Agoric Approach to Computing

Agoric computing is a concept of structuring computation and business systems around the model of a free market, supplanting traditional systems which often resemble top-down, centrally planned economies. It encompasses smart contracts, which are central to the emerging field of decentralised finance (DeFi), which is not entirely 100% scams and pyramid schemes, despite how it may appear. In this 42 minute long conversation, the CEO and Chief Scientist of Agoric Systems Operating Company trace the history of smart contracts back to the pioneering work at the American Information Exchange (AMIX) in the 1980s (backed by Autodesk from 1988 through 1992), describe how smart contracts are integrated with blockchain technology, and explain why they have chosen JavaScript as the language on which to build their technology.

Posted at 12:18

THE HAPPENING WORLD: Lucy—Visiting Eight Asteroids with One Spacecraft

NASA's Lucy mission is scheduled to launch on Saturday, 2021-10-16 at 09:34 UTC. Its planned twelve-year mission will use multiple Earth gravity assists to fling it on a path through both the leading and trailing Trojan regions of Jupiter, where it will encounter seven asteroids, including some believed to date from early in the formation of the solar system. Lucy will also fly by a small main belt asteroid on its outbound trajectory. Here is a live Webcast of the launch.

Posted at 11:57

CONTINUITY: Before GPS—The Navy Navigation Satellite System

This 1967 U.S. Navy training film describes the Transit satellite navigation system, which went into service in 1964, providing global coverage with position fixes every several hours at the equator and more frequently at higher latitudes. Its original mission was providing position information to Polaris ballistic missile submarines, and was later adopted by a wide variety of surface ships. The architecture was very different from GPS, and relied upon Doppler measurement of transmissions from a constellation of five satellites in low polar orbit. Each satellite transmitted an ephemeris of its position, updated daily from a computer centre on the ground and a network of tracking stations, from which shipboard computers could calculate position based upon the observed Doppler shift. Only one satellite was needed to provide 2D (latitude and longitude) accurate to originally 400 metres but eventually improved to around 200 metres as the system was refined. The Transit system remained in service until 1996, when it was retired in favour of the Global Positioning System (GPS), which had become fully operational (continuous global coverage) the preceding year, but since the 1980s had provided better and more frequent 3D position fixes than Transit.

Posted at 11:19

Thursday, October 14, 2021

TRACKING WITH CLOSEUPS: Payout Mechanism from a Vintage Slot Machine

Posted at 13:55

CONTINUITY: Fifty Years Ago—The First Commercial Video Game

50 years ago, in October 1971, the first commercial video game made its debut. And no, we're not talking Pong. https://t.co/7s1PEhREbP

— American Experience (@AmExperiencePBS) October 14, 2021

Here is a game play video.

Posted at 13:22

THE HAPPENING WORLD: Space Tourism Companies Prohibit Passengers from Selling Souvenirs

Commercial spaceflight companies set limits on carry-ons: souvenirs not for sale: https://t.co/eZRogAuCt5 pic.twitter.com/0Me3UT7PdR

— collectSPACE (@collectSPACE) October 12, 2021

“Commercial space” for vendors, not customers.

Posted at 12:52

CONTINUITY: How Photolithography Works—Part 6: Resolution Enhancement

The ultimate limit on the feature size photolithography can produce is set by the wavelength of the light it uses and the physics of electromagnetism, but clever device designers have invented a bag of dirty tricks to squeeze more onto a chip. The series concludes with a survey of some of these techniques, including multiple exposure and etching cycles, atomically deposited spacers, self-assembling molecules, and three-dimension stacking of transistors.

Posted at 12:05

CONTEXT: Visiting a Server Farm in Germany

Posted at 11:38

Wednesday, October 13, 2021

CONTEXT: What Did Dinosaurs Really Look Like?

Artist C. M. Kosemen has drawn modern animals as they might be reconstructed from their skeletons alone: “Nightmarish sketches reveal what modern animals would look like if we drew them in the same way as dinosaurs based on their skeletons”.

Posted at 14:28

TRACKING WITH CLOSEUPS: Destructive Interference: Cancelling Light

Where does the energy go?

Posted at 14:16

CONTEXT: Float-Through McDonald's

You'll never guess in which German city it's located.

Posted at 13:17

CONTINUITY: James Webb Space Telescope Arrives in French Guiana

#Webb has arrived safely at Pariacabo harbour in French Guiana! 🛥 🚀@ESA in close collaboration with @NASA will now prepare this once in a generation mission for its launch on @Ariane5 from Europe’s Spaceport this December. #WebbFliesAriane

Read more👉 https://t.co/Pem37g0fBP pic.twitter.com/LFUeYZnL1a

— ESA Webb Telescope (@ESA_Webb) October 12, 2021

Launch on Ariane 5 flight VA256 is scheduled for December 18, 2021.

Posted at 12:02

THE HAPPENING WORLD: Blue Origin New Shepard NS-18 Launch

The Webcast coverage is scheduled to start at 12:30 UTC on 2021-10-13.

Posted at 11:38

Tuesday, October 12, 2021

CONTEXT: Why Do Bees Make Rhombic Dodecahedrons?

Posted at 14:39

CONTINUITY: Why Do U.S. Power Plugs Have Those Holes in the Prongs?

The dead hand of the past meets Safetyland's electric plugs, some of the worst and most stupid in the world.

Posted at 14:16

CONTINUITY: How Photolithography Works—Part 5: Photolithography Metrics

Photoresists (see Part 3) are highly nonlinear (or, as a photographer would say, high contrast). Getting the “dose” (or exposure) correct is critical for imaging small features, and this is a tradeoff between focus and illumination, which involves some intricate measurements and calculations.

Posted at 12:46

TRACKING WITH CLOSEUPS: Firefly Aerospace Factory and Test Site Tour

Posted at 12:12

Monday, October 11, 2021

CONTEXT: Linkage Mechanism Converts Binary to Decimal

Mathematics, computer programming, engineering, motion, creativity.

This is a linkage-mechanism for converting binary numbers to decimal numbers. Created by 上木 敬士郎/Keishiro Ueki, @KeishiroUeki pic.twitter.com/ONUtCT2AkM

— Cliff Pickover (@pickover) October 10, 2021

Posted at 14:15

THE HAPPENING WORLD: Attack Submarine USS Connecticut Collides with “Object”—What Happened?

Here is more about the incident at the U.S. Naval Institute Web site, “Attack Submarine USS Connecticut Suffers Underwater Collision in South China Sea”. This is the official statement by the U.S. Navy. The name of the Connecticut's captain is Bill Clinton.

Posted at 12:20

THE HAPPENING WORLD: Tesla Rolling Out “Full Self-Driving” Beta 10.2 by “Safety Score”

FSD Beta 10.2 rolls out Friday midnight to ~1000 owners with perfect 100/100 safety scores.

Rollouts will hold for several days after that to see how it goes.

If that looks good, beta will gradually begin rolling out to 99 scores & below.

— Elon Musk (@elonmusk) October 7, 2021

Beta 10.2 now rolling out to cars with 100/100 safety score over 100 miles

— Elon Musk (@elonmusk) October 11, 2021

SCANALYZER has previously written about Tesla's “Safety Score” spyware which monitors customers' driving behaviour and reports back to headquarters. Now it's official: customers who have paid for Tesla's so-called “Full Self-Driving” capability will receive beta test updates in descending order by safety score, with only those who have a perfect score of 100/100 in the last 100 miles receiving the update first.

Perhaps a future update will monitor their customers' body mass index based upon seat settings and a weight sensor in the driver's seat and refuse to drive to fast food restaurants if it's too high.

“They'll go into debt to buy their own shackles” — Kelvin R. Throop

Posted at 11:17

CONTINUITY: Learning to Land the Space Shuttle—Approach and Landing Tests

Posted at 10:47

Sunday, October 10, 2021

CONTINUITY: How Photolithography Works—Part 4: Imaging Process

How do you make an image whose feature sizes are smaller than the wavelength of light you're using? It might seem like black magic, but it's really a matter of light magic, involving a bag of dirty tricks called “Optical Proximity Correction” (OPC), which take into account the wave properties of light and construct masks which often look nothing like the image they create, but create interference patterns which form the desired features. “Think of your semiconductor wafer as a 160 gigapixel camera image sensor.”

Posted at 15:25

TRACKING WITH CLOSEUPS: French Cuisine in Space

European Space Agency astronaut Thomas Pesquet describes food on the International Space Station, including the “crew preference food” he brought to supplement the basic fare provided by NASA. The audio is in French, with English subtitles. (If the subtitles are not automatically enabled, click the “CC” box at the bottom to turn them on.)

Posted at 14:10

CONTEXT: Edward Snowden on “Central Bank Digital Currencies”

A CBDC is a perversion of cryptocurrency, or at least the founding principles and protocols of it—a cryptofascist currency, expressly designed to deny you the basic ownership of your money by installing the State at the center of every transaction. https://t.co/720SYvqzZM

— Edward Snowden (@Snowden) October 9, 2021

Central Bank Digital Currencies or, as I like to call them, “slave money”, are a hot topic among globalists and other would-be slavers. Just imagine how wonderful it will be when your government can confiscate your cash remotely with the click of a mouse, control the things on which you can spend it, or keep you from spending it entirely if you have done something of which they disapprove. I have been warning about this ever since my “Unicard: Ubiquitous Computation, Global Connectivity, and the End of Privacy” paper in 1994, which was considered dystopian science fiction at the time.

In a few years, countries that aspire to economically enslave their populations won't even have to develop their own systems for doing so—they'll be able to buy it off the shelf as a turnkey system from China, integrated with the “social credit” system.

Posted at 12:34

THE HAPPENING WORLD: Weekly Space Report: Starbase Developments, 33 Raptor Super Duper Heavy, Amazing 3D Raptor Model, Ingenuity Grounded

Posted at 11:20

Saturday, October 9, 2021

CONTINUITY: Boeing Starliner OFT-2 “Hangar Queen”—One Valve Still Stuck, “Working Toward Launch Opportunities in the First Half of 2022 “

The highly anticipated Starliner update doesn’t have any major revelations, except maybe that one of the valves is still stuck. “Several paths forward” range from “minor refurbishment” of service module components to using a new service module. https://t.co/5WwlgD5s0I

— Jeff Foust (@jeff_foust) October 8, 2021

Posted at 14:45

CONTEXT: How Virtual Worlds Work—Part 3, Digital Objects

👀There’s more to digital objects than meets the eye…

In part 3 of this series, @raphkoster breaks down what a virtual object actually is. Learn more here: https://t.co/apTojaLmO7#GameDev #VirtualWorlds #Metaverse pic.twitter.com/8DB1p9Y4ge

— Playable Worlds (@PlayableWorlds) October 7, 2021

Posted at 12:49

CONTINUITY: SpaceX Completes Secondary Share Offering at Valuation of US$ 100.3 Billion

The company now has a valuation of $100.3 billion (at $560/share), up from $74 billion (at $419.99/share) in February, after a secondary sale announced this week, according to sources familiar with the deal.https://t.co/Yz8U1sPyu9

— Michael Sheetz (@thesheetztweetz) October 8, 2021

If you're looking at only the space segments of the other companies, SpaceX is bigger than all of them. https://t.co/EYRxvu9649

— Not-So-OK Boomer (@Rand_Simberg) October 8, 2021

Posted at 12:08

TRACKING WITH CLOSEUPS: The Schmid Peoplemover

Posted at 11:28

Friday, October 8, 2021

THE HAPPENING WORLD: Elon Musk at the 2021 Tesla Annual Shareholder Meeting

“Over time, you'll see all manufacturers will make electric vehicles, and eventually all manufacturers will make autonomous vehicles. Tesla is open to licensing autonomy.

“… you can recycle battery materials. You can think of batteries as essentially high grade ore. So you can get your lithium and your nickel … from rocks or from batteries. It's much better to get them from batteries.”

Posted at 14:52

CONTEXT: “Slowed Canonical Progress in Large Fields of Science”

Makes sense: "Examining 1.8 billion citations among 90 million papers across 241 subjects, we find a deluge of papers does not lead to turnover of central ideas in a field, but rather to ossification of canon." https://t.co/sk209DLeKB

— Robin Hanson (@robinhanson) October 6, 2021

Abstract

In many academic fields, the number of papers published each year has increased significantly over time. Policy measures aim to increase the quantity of scientists, research funding, and scientific output, which is measured by the number of papers produced. These quantitative metrics determine the career trajectories of scholars and evaluations of academic departments, institutions, and nations. Whether and how these increases in the numbers of scientists and papers translate into advances in knowledge is unclear, however. Here, we first lay out a theoretical argument for why too many papers published each year in a field can lead to stagnation rather than advance. The deluge of new papers may deprive reviewers and readers the cognitive slack required to fully recognize and understand novel ideas. Competition among many new ideas may prevent the gradual accumulation of focused attention on a promising new idea. Then, we show data supporting the predictions of this theory. When the number of papers published per year in a scientific field grows large, citations flow disproportionately to already well-cited papers; the list of most-cited papers ossifies; new papers are unlikely to ever become highly cited, and when they do, it is not through a gradual, cumulative process of attention gathering; and newly published papers become unlikely to disrupt existing work. These findings suggest that the progress of large scientific fields may be slowed, trapped in existing canon. Policy measures shifting how scientific work is produced, disseminated, consumed, and rewarded may be called for to push fields into new, more fertile areas of study.

Here is the full paper, “Slowed canonical progress in large fields of science”. I repeat my frequent observation, “Once Pareto gets into your head, you'll never get him out.”

Posted at 14:06

CONTINUITY: How Photolithography Works—Part 3: Photoresist

Photoresist is the “secret sauce” of microelectronics. It is a chemical coating which, applied to a silicon wafer, is rendered soluble or insoluble by exposure to light. Post-exposure, the soluble part is washed away, leaving a mask which protects portions of the chip not to be affected by the next processing step. This sounds simple, but achieving nanometre resolution and avoiding optical distortion are formidable challenges which have been surmounted as device geometries shrink.

Posted at 13:06

TRACKING WITH CLOSEUPS: “Never Mind”—“Gamma Ray Burst” From Remote Galaxy Turns Out To Be Flash From Space Junk

Sunlight reflected of a piece of #spacedebris confused astronomers to think they had seen a #gammarayburst in the oldest known galaxy. Science is sometimes about disappointment, but the impact of satellites and space debris on astronomy is a serious issue.https://t.co/qSuc3nteES

— Tereza Pultarova (@TerezaPultarova) October 7, 2021

Detection of an apparent gamma ray burst in the act of occurring in a galaxy at redshift 11, indicating we are observing it as it was just 420 million years after the big bang was reported in the paper “A possible bright ultraviolet flash from a galaxy at redshift z ~ 11” in December 2020. “Not so fast” responded other astronomers, in the paper “A more probable explanation for a continuum flash in the direction of a redshift ≈ 11 galaxy” and elsewhere, pointing out the extreme improbability of such an observation and the far more likely explanation that it was a transient due to reflection from an orbiting satellite or space junk. Now the case has been closed with the publication of “GN-z11-flash was a signal from a man-made satellite not a gamma-ray burst at redshift 11” which identifies the flash as a glint of sunlight from a derelict Breeze-M upper stage from a Russian Proton rocket in a highly elliptical orbit.

Posted at 12:14

CONTINUITY: Apollo Spacecraft S Band Communication System, Part 2

Communications from the Apollo spacecraft to ground stations were via an S band microwave link with a radiated power of 11.6 watts. The signal sent to the antenna was produced by the transponder unit and amplified by a traveling wave tube. This episode digs into the radio frequency (RF) power amplifier, explains its complicated system of relays providing redundancy, and describes how a traveling wave tube works and why they remain in use on contemporary spacecraft.

Posted at 11:44

Thursday, October 7, 2021

CONTINUITY: NASA Transfers Crew Assigned to Boeing Starliner to SpaceX Crew Dragon

As Starliner delays worsen, NASA plans to move some astronauts off the vehicle's first two flights and onto the SpaceX Crew-5 mission next year. https://t.co/kyQqIoYbht

— Eric Berger (@SciGuySpace) October 5, 2021

🚀 Astronauts @AstroDuke and @astro_josh have been reassigned to @NASA's @SpaceX Crew-5 mission. Mann and Cassada will serve as spacecraft commander and pilot, respectively, for this flight. Additional crew members will be announced later: https://t.co/z15Kfe0FeU pic.twitter.com/16jYsAFoDP

— NASA Commercial Crew (@Commercial_Crew) October 6, 2021

With the unmanned orbital test flight of Starliner “Hangar Queen” slipping into 2022, NASA decided the astronauts scheduled to make their first space flight on Starliner shouldn't have to wait any longer.

Posted at 15:02

CONTINUITY: Ten Unsettling Possibilities Regarding Alien Life

It was interesting to hear the scenario from my science fiction short story “We'll Return, After This Message” figure in one of the segments.

Posted at 14:34

THE HAPPENING WORLD: „Вызов” (The Challenge)—Teaser Trailer

Filming (or, more precisely, videography) of the 30 to 40 minutes of the feature film „Вызов” (literal translation: “Doctor's House Call”) is presently underway on the International Space Station.

Posted at 13:13

CONTEXT: The “I Can't Believe It Can Sort” Algorithm

A funny new sorting algorithm from https://t.co/6f9IqcxIGj pic.twitter.com/7fBYXjUVd6

— Nicole Wein (@WeinNicole) October 5, 2021

The abstract: “We present an extremely simple sorting algorithm. It may look like it is obviously wrong, but we prove that it is in fact correct. We compare it with other simple sorting algorithms, and analyse some of its curious properties.” Here is the full text, “Is this the simplest (and most surprising) sorting algorithm ever?” [PDF].

Posted at 12:54

THE HAPPENING WORLD: Why Did Facebook Fail?

While the Facebook bungle has been widely described in the media as a “DNS problem”, it seemed to me from the outset that it was more likely to be due to BGP, the Border Gateway Protocol, one of the least known and potentially vulnerable part of the Internet's infrastructure. BGP, first defined in 1989 and in use on the Internet since 1994, dates from the era when the Internet was composed of a relatively small number of technically proficient and trustworthy institutions, and assumes those running it share those attributes. BGP is how the Internet routes packets among the multitude of independent networks that participate in its common network. The routers that run BGP accept routing information advertised by their peers by default. This means that a malicious router can pollute the routing tables of other routers, a form of attack known as BGP hijacking, of which a number of notable incidents have occurred, including that time in 2008 when Pakistan tried to block YouTube and ended up taking down YouTube world wide. But BGP's insecurity makes it just as prone to calamity from an unintentional fat-finger as deliberate malice, and that appears to be what happened to Facebook. It was perceived as a “DNS problem” only because Facebook's DNS servers had disappeared from the Internet, but so had everything else in Facebook's IP address ranges—that's the signature of a BGP face-plant.

BGP is neither simple nor straightforward, which is one reason it is little known, poorly understood, and easy to mess up. Here is an hour and a half deep dive into BGP, which may leave you even more confused that you are now.

Posted at 12:13

CONTEXT: Cryptocurrency vs. Kleptocurrency

Cryptocurrency vs. kleptocurrency—this is how the market responds to more than a century of pocket-picking by central banks. Kleptocurrencies issued by debt-crater railroad-era continental scale empires will be rendered impotent and obsolete by market-based competition. pic.twitter.com/j08jLjWmQW

— John Walker (@Fourmilab) October 7, 2021

Here's the chart, in case you'd like to edit it or compare to other time series.

Posted at 01:15

Wednesday, October 6, 2021

CONTEXT: Reading List: Escape the City, Vol. 1

Corcoran, Travis J. I. Escape the City, Vol. 1. New Hampshire: Morlock Publishing, 2021. ISBN 979-874270303-7.

In early 2014, the author and his wife left the suburbs of Boston and moved to a 56 acre homestead in rural New Hampshire. Before arriving, he had done extensive reading and research, but beyond the chores of a suburban homeowner, had little or no hands-on experience with the myriad skills required to make a go of it in the country: raising and preserving garden vegetables; maintaining pastures; raising chickens, sheep, and hogs, including butchering and processing their meat; erecting utility buildings; planting and maintaining a fruit orchard; tapping maple trees and producing syrup from their sap; managing a wood lot, felling and processing trees, storing and aging firewood and heating with it; and maintaining a tractor, implements, chainsaws, and the many tools which are indispensable to farm life. The wisdom about how tradesmen and contractors work in the country in the section “Life in The Country: Cultural Fit: Scheduling” would have been worth more than the modest price of the book had I learned it before spending a decade and a half figuring it out for myself after my own escape from the city in 1992.

This massive work (653 large pages in print) and its companion Volume 2 are an encyclopedic compendium of lessons learned and an absolutely essential resource for anybody interested in self-sufficient living, whether as a “suburbanite in the country”, “gardener with chickens”, “market gardener”, “homesteader”, or “commercial farmer”, all five of which are discussed in the book.

The Kindle edition is free for Kindle Unlimited subscribers. The numerous illustrations are in black and white in print editions, but colour in the Kindle version.

Posted at 21:14

CONTINUITY: TOI-178—Music of the Spheres

The exoplanet system TOI-178 in the constellation of Sculptor has six planets orbiting close to a K type orange dwarf star. Five of the planets appear to be locked into a chain of Laplace resonances, resulting in regular alignments as they orbit. This artist's animation shows the planets orbiting the stars, with musical notes playing for each planet as it completes a half orbit. When planets align at these points, a resonance is heard.

Posted at 13:58

THE HAPPENING WORLD: Finally—Optical Illusion Jeans for “Perky Buttocks”

Lee has patented jeans that use an optical illusion to "make the buttocks appear round and/or perky."
Patent No. 11129422 pic.twitter.com/IGMV8HpU7N

— Jeff Steck (@GazEtc) October 5, 2021

Here is U.S. Patent 11,129,422, “Body-enhancing garment and garment construction” (full text).

Posted at 13:29

CONTINUITY: How Photolithography Works—Part 2: Photolithography Basics

Posted at 12:47

TRACKING WITH CLOSEUPS: Blue Origin: 2018 Consultants' Report Warns of Lack of Focus

Why SpaceX is better than Blue Origin. By, err, Blue Origin.

Revealed: The secret notes of Blue Origin leaders trying to catch SpaceX https://t.co/hVy8qZFRBB

— NickStevens Graphics (@Nick_Stevens_Gr) October 5, 2021

In 2018, Blue Origin hired a consultant firm to assess Blue's competitive position with respect to SpaceX. Ars Technica has obtained a copy of the their report to CEO Bob Smith, which Eric Berger summarises in an article, “Revealed: The secret notes of Blue Origin leaders trying to catch SpaceX” published on 2021-10-04. The memo included some pungent quotes from senior Blue Origin managers.

They [SpaceX] have a customer focus. We should too. In many cases we view the customer as a nuisance. … We need to change this culture.

SpaceX shifted the market to their payload capabilities and risk profile with their low-cost launches. Blue has pushed to exceed the market’s current capabilities for size and mass. … How confident are we that the market will design to our capabilities?

Cost as a design constraint and important variable is embraced by their [SpaceX's] culture, instead of being viewed as an evil metric that leads to a sub-optimal outcome.

Blue is riddled with poor estimating. The estimates barely cover the spot cost buy of that material based on market price, let alone the entire part material purchase. How did SpaceX keep to their target cost? They probably did a good job estimating. How they accomplished such good estimating is beyond me right now, but they did it somehow for their early years.

I would like to see us change how we reward teams and individuals for company or project level success. Dinners, shirts and parties can only get us so far. I think real and meaningful financial incentives for Blue employees can help.

My strategy at Autodesk was just:

1. Make the best product.
2. No bullshit.
3. Reward the people who do the work.

Perhaps Blue Origin could adopt a similar approach.

Posted at 11:53

Tuesday, October 5, 2021

CONTINUITY: F-111 Terrain Following Radar

This training film shows the F-111's terrain following radar in action. Did you know that it had a “ride control” which set how closely it would stick to the actual terrain contour, expressed in how many Gs it would pull in climb and dive maneuvers to maintain the set altitude?

Posted at 14:03

TRACKING WITH CLOSEUPS: Bad Rigging: Why Things Fall from Cranes

I'll bet many people using hoists fail to account for the “cosine loss” when multiple straps are used at an angle to the vertical. The shallower the angle of the strap, the more of its strength is wasted on horizontal force which simply cancels the horizontal force of the other strap(s).

Posted at 13:17

CONTEXT: Transparent Monsters: Underestimating the Human Potential

This is a good introduction to what I call the “human endowment”—a future in which humans and their descendants will bring life, consciousness, and purpose to a solar system and beyond which awaits them. David Deutsch's The Beginning of Infinity is an excellent introduction to humans as “universal explainers” and the consequences of that for the cosmos.

Posted at 12:26

THE HAPPENING WORLD: William Shatner to Fly to Space on Blue Origin New Shepard

Blue Origin says actor William Shatner, who played Captain Kirk on “Star Trek,” will fly into space on a suborbital launch Oct. 12 from West Texas.

Shatner will join a Blue Origin vice president and two paying passengers on the flight.

Read more: https://t.co/sDyCUS9xYf pic.twitter.com/rn4qkC7gHN

— Spaceflight Now (@SpaceflightNow) October 4, 2021

Shatner is scheduled to fly on mission NS-18 on 2021-10-12, along with Blue Origin vice president Audrey Powers and two paying passengers. At age 90, he will become the oldest person to fly in space, eclipsing the record set by Wally Funk, 82, on the first crewed New Shepard flight.

There were earlier rumours that Shatner was to fly on Virgin Galactic's ship, but it appears he decided that after so many years exploring strange new worlds, seeking out new life and new civilisations, he didn't want to go into the record books as an “asterisknaut”.

Posted at 11:57

THE HAPPENING WORLD: Soyuz MS-19 Launch to the International Space Station

As described in yesterday's post, Soyuz MS-19 is on its way to the International Space Station. I have cued the video to start one minute before launch: scroll backward if you wish to see the more than three hours of preliminary material.

Here is Scott Manley with more details about the mission and another forthcoming cross-over episode of fictional and real space flight, plus the last Khan of Kazakhstan.

Posted at 11:32

Monday, October 4, 2021

CONTINUITY: How Photolithography Works—Part 1: Introduction

The semiconductor revolution is largely based upon the ability to manufacture identical complex objects in enormous quantities just by taking pictures of them, a process known as photolithography. But how does it work? This exploration begins with the basics: transistors, Moore's Law, and the exponential growth in the number of transistors manufactured, which is now approaching the number of stars in the visible universe.

Posted at 15:25

THE HAPPENING WORLD: Soyuz MS-19 to Launch Film Crew to International Space Station

In less than 24 hours, @roscosmos will launch the crew of "The Challenge" movie atop a #Soyuz 2.1a to the @Space_Station!! Learn more about all the details of the first drama movie in space in our article by @mankaitown!https://t.co/NM6IP2sHcc

— Everyday Astronaut (@Erdayastronaut) October 3, 2021

Launch is scheduled for 08:55 UTC on 2021-10-05. On board will be Anton Shkaplero, commander and flight engineer, film director Klim Shipenko, and actress Yulia Peresild. The 12 day mission is to film footage for the dramatic series “The Challenge”, the first four episodes of which may be viewed at 1tv.ru.

Posted at 14:10

TRACKING WITH CLOSEUPS: Flying Insects at 6000 Frames per Second

Posted at 13:47

CONTEXT: Chaos in the Cockpit—Botched A350 Go-Around at Paris Orly

The video observes that long haul airline crews make so few landings that five years may elapse between their having to perform a go-around in the real world (as opposed to the simulator).

Posted at 11:28

Sunday, October 3, 2021

CONTINUITY: The Rolls-Royce Merlin Engine

Best known for powering the World War II Spitfire, Hurricane, and Mustang fighters, the many models of Rolls-Royce Merlin were used in more than forty aircraft types and was even adapted into a variant called the Meteor, used in nine models of British tanks, and remaining in production until 1964.

Posted at 15:23

CONTINUITY: India's Evolving Space Launch Vehicles

Posted at 14:16

CONTEXT: Blue Bananas, Autumn Leaves, Chlorophyll, and Programmed Cell Death

Posted at 12:07

THE HAPPENING WORLD: Weekly Space Report: Starship Cryogenic Testing Begins, Tiles Fall, Lucy Asteroid Mission Launch

Posted at 11:38

Saturday, October 2, 2021

CONTINUITY: MOSFET—How the Metal Oxide Semiconductor Field Effect Transistor Changed the World

I remember when I first played around with a 3N128 [PDF] metal insulated gate field effect transistor in the mid-1960s. It was the first essentially ideal electronic component I ever encountered. The gate current was essentially zero—just what you needed to charge or discharge its tiny capacitance, and response was almost perfectly linear within its specified range. There was no gate protection: you had to be very careful not to zap the gate with static electricity when the device was not in circuit. Who could have imagined that, half a century later, its silicon descendants would be manufactured in quantities of thousands of trillions per day—the product the most manufactured in human history? The number of MOSFETs made per year is around two million times the number of stars in the Milky Way galaxy, and the number made since their invention now exceeds the highest estimates for the number of grains of sand in all of the beaches of the Earth.

Posted at 12:36

CONTINUITY: Post-Apocalyptic Fiction

#NevilShute pic.twitter.com/1FE1ALmNbd

— NevilShute.org (@Nevil_Shute_org) September 25, 2021

Posted at 12:17

CONTEXT: Akademik Lomonosov—Russia's Floating Nuclear Power Plant

Here is more about the Akademik Lomonosov, which went into service on May 22nd, 2020, delivering 70 megawatts (electric) from two KLT-40S naval propulsion reactors to the arctic community of Pevek in the Russian far east. Sixty megawatts of waste heat from the power plant is used in a community heating system, and a desalination plant provides fresh water to the town.

Posted at 11:46

THE HAPPENING WORLD: James Webb Space Telescope—Hardware and Science

Posted at 11:19

TRACKING WITH CLOSEUPS: Apple iPhone 13 Anti-Repair “Features”

Pretty much every component is “paired”, and only Apple has the tools to re-pair (heh) replacements. Swap a failed part for a spare, and features just magically go away. Just another reason I'm glad I bid adieu to the Pod people when the battery in “old sweller” tried to escape the case.

Posted at 10:19

Friday, October 1, 2021

CONTINUITY: Navigating Virtual Worlds

Virtual Worlds are places. But how the heck are we going to move between them?

Read all about it in Part 2 of @raphkoster's latest article series here: https://t.co/KZDNqSANoc#VirtualWorlds #MMO #Metaverse pic.twitter.com/hhxpt0aW5p

— Playable Worlds (@PlayableWorlds) September 30, 2021

The second part of Raph Koster's series, “How Virtual Worlds Work” (read Part 1) discusses the nature of maps of real versus imaginary spaces, moving around the map vs. a map tracking your movement, and the need for standards that treat maps in a compatible way that represents connectiivity, nor just artwork, as is so often the case.

It's easy to imagine a metaverse where “it's all connected, and you can go anywhere preserving your identity”, as envisioned in Ready Player One. But how will this really work and feel in practice?

By definition though, any multiverse (and remember, a metaverse is just a more advanced version of a multiverse) is going to involve many very different places. You don’t want those all to exist on one map. You’d end up with Fairyland butting up against World War II.

Aesthetics isn’t the main reason this is bad. The real issue is that players won’t be happy if they were expecting a nice peaceful tea party with talking flowers, but they took one step too far, and were run over by a Sherman tank.

For a glimpse of artificial reality as it might actually look if implemented by today's creators of “social media” with the underlying quality and respect for the customer we've come to expect from outfits such as Microsoft, Facebook, Twitter, and Google, see the short video cited in the paper, “Hyper-Reality” by Keiichi Matsuda.

Posted at 14:27

THE HAPPENING WORLD: Intel Announces Neuromorphic Chip with One Million Neurons, 4 Nanometre Process

Today @Intel Launches Loihi 2, a Neuromorphic chip. With a million neurons, it is super small, and designed to do brain-like things on only a few milliwatts. It's also exciting because this is Intel's first 4nm (Intel 4) chip with EUV.https://t.co/OWSB9BiPbH

Tip @techmeme pic.twitter.com/0udrZgDq3f

— AnandTech (@anandtech) September 30, 2021

Here is an interview with Mike Davies, director of Intel's Neuromorphic Computing Lab, on the architecture of the Loihi 2 chip, applications of neuromorphic (biomimetic) technology, and how such systems are interfaced to conventional computers. Here is a technical brief [PDF] on Loihi 2 and the Lava software framework that supports it, which allows simulation of neuromorphic systems on conventional hardware. Lava is available for free from GitHub.

Posted at 12:29

TRACKING WITH CLOSEUPS: Soyuz MS-18 Repositioning at International Space Station—Onboard TIme Lapse

This (now iconic) relocation maneuver of the Soyuz TMA-18 on August 28, 2015 from the Poisk docking module to the Zvezda module of the ISS, was filmed with a GoPro camera and shows you how change parking spots in space [read more: https://t.co/OonrBA783r] pic.twitter.com/Kidp1J6zay

— Massimo (@Rainmaker1973) September 30, 2021

Posted at 11:55

CONTEXT: Solar Observation Spacecraft Discover Sun-Grazing Comets

Prior to the advent of space-based solar observatories, a multitude of small comets plunged in from the outer solar system and closely approached the Sun without being observed—astronomers may have suspected they existed, but there was no way to see them in the glare of the Sun. After the launch of the SOHO spacecraft in 1995 and successors since then, more than four thousand sungrazing comets have been observed, most of which disintegrate when they pass close to the Sun and do not emerge from their perihelion passage. Many of these are of the Kreutz sungrazer family, which are believed to have originated from a single large comet which broke up when passing near the Sun several centuries ago.

Posted at 10:38