Recently in CONTINUITY

Saturday, October 30, 2021

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 Permalink

Friday, October 29, 2021

“Spot Me Up”

Posted at 12:15 Permalink

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 Permalink

Thursday, October 28, 2021

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

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

Posted at 10:46 Permalink

Wednesday, October 27, 2021

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 Permalink

Tuesday, October 26, 2021

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 Permalink

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 Permalink

Monday, October 25, 2021

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

Posted at 11:50 Permalink

Sunday, October 24, 2021

ARM1 from 1985 vs. Apple M1 Max

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

Posted at 12:38 Permalink

Saturday, October 23, 2021

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 Permalink

Friday, October 22, 2021

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 Permalink

Thursday, October 21, 2021

From 1947—Office Automation Before the Computer

Posted at 13:28 Permalink

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 Permalink

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 Permalink

Wednesday, October 20, 2021

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 Permalink

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 Permalink

Tuesday, October 19, 2021

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.

stand_2016-07-01.jpg

Posted at 12:43 Permalink

Monday, October 18, 2021

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 Permalink

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 Permalink

Sunday, October 17, 2021

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

Posted at 13:46 Permalink