Friday, October 22, 2021


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 Permalink


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

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

Posted at 11:38 Permalink

TRACKING WITH CLOSEUPS: Embryonic Development of the Alpine Newt

Posted at 11:08 Permalink

Thursday, October 21, 2021

CONTINUITY: From 1947—Office Automation Before the Computer

Posted at 13:28 Permalink

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 Permalink

CONTEXT: Ducks in a Row

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

Posted at 12:13 Permalink

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 Permalink

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.


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 Permalink

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

Posted at 14:19 Permalink

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 Permalink

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 Permalink

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 Permalink

Tuesday, October 19, 2021

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

Posted at 12:59 Permalink

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 Permalink

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

Posted at 11:30 Permalink

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 Permalink

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 Permalink

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 Permalink

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 Permalink