You can actually give a semi-plausible justification of special relativity based on what was known in 1901. Maxwell's equations are fundamentally incompatible with what I might call "Newtonian relativity." They define a fixed speed for light, which is impossible in Newtonian relativity for observers in different inertial reference frames. Magnetism is also a puzzle, as the magnetism depends on the relative velocity in a way that makes it appear to create different forces in different inertial frames. Without length contraction from special relativity, magnetism has uncomfortable implications.

"You can actually give a semi-plausible justification of special relativity based on what was known in 1901."

You can give a semi-plausible justification for anything. It was obvious at the time that our knowledge was incomplete, but the specific *way* in which our knowledge was incomplete was still a mystery. It is very easy to invent a plausible-sounding quack theory of physics; that is why we have the Crackpot Index.

You can actually give a semi-plausible justification of special relativity based on what was known in 1901. Maxwell's equations are fundamentally incompatible with...

Yes, this is the chain of logic that Einstein followed in 1905. But it was followed in 1905, not 1901, despite plenty of other physicists focusing on the question.

There's a reason why I did not list the "semi-plausible justification" in my account of the Bizarre Speed Limit. People typically try to judge absurdity by surface features, without in-depth study of a topic.

It might be worthwhile to list statements about present-day society that would have seemed incredible to me at various times in the past. For example:

1. That nobody has been to the moon since 1972.

2. That the Soviet Union no longer exists and there has been no nuclear war. (One or the other would have been plausible but not both.)

3. That we're still using fossil fuels on a large scale.

4. President Ronald Reagan.

5. That there is a major communications network that is not run by any single organization.

6. That there would be a high-quality computer operating system based on free software.

Length contraction was proposed by George FitzGerald in 1889, in response to the Michelson-Morley experiment, and it gained greater circulation in the physicist community after Hendrik Lorentz independently proposed it in 1892. I imagine that most top physicists would have been familiar with it by 1901. Lorentz's paper included the ideas that the relative motion of reference frames was important, and that funny things were going on with time (like non-simultaneity in different reference frames), and his 1899 follow-up included time dilation equations (as did a less-known 1897 paper by Joseph Larmor). I'm not sure if people familiar with this work saw c as the universal speed limit, but the length contraction equations (which imply imaginary length for v greater than c) suggest that this proposal wouldn't strike them as crazy (and they would have recognized the number as c, since estimates of the speed of light were accurate within less than 0.1% by then).

Unnamed, remember that the histories we read promote particular events to prominence, while all others fade into the background; but to the people alive at the time, there are plenty of distractions.

I agree that future events of the most "absurd" sort are often predicted by at least some specialists paying very close attention to the field. This does not interfere with the lesson that I personally draw from history, which is that you have to go very deep and very technical in order to evaluate the possibility of a future event - surface absurdity counts for nothing.

Megan McArdle reposts this, though alas without a link.

I could believe in the spanking thing happening pretty easily. (I could believe it pretty easily. It wouldn't happen easily.) A society with a different approach to deterrence/punishment, a different view of the relative cruelty of prison vs. corporal punishment, etc. The others require violations of our concepts of physics, economics. Changing the punishment structure doesn't violate our ideas of human nature/psychology, etc.

A while back, Marvel Comics put out a "2099" group of books. The premise of the "Punisher 2099" series was that the civil tort system had replaced the criminal justice system entirely. A violent Paris Hilton type murders Punisher's entire family, and he goes vigilante.

Although, I guess it compares fairly with a black person becoming President in 1901. A few people with broad knowledge might find it possible but radically unlikely. It's a fair cop, and shame on Janegalt.net.

I could believe in the spanking thing happening pretty easily. (I could believe it pretty easily. It wouldn't happen easily.) A society with a different approach to deterrence/punishment, a different view of the relative cruelty of prison vs. corporal punishment, etc. The others require violations of our concepts of physics, economics. Changing the punishment structure doesn't violate our ideas of human nature/psychology, etc.

A while back, Marvel Comics put out a "2099" group of books. The premise of the "Punisher 2099" series was that the civil tort system had replaced the criminal justice system entirely. A violent Paris Hilton type murders Punisher's entire family, and he goes vigilante.

Although, I guess it compares fairly with a black person becoming President in 1901. A few people with broad knowledge might find it possible but radically unlikely. It's a fair cop, and shame on Janegalt.net.

judging by where the commments took this discussion on Megan's blog, she may have been doing you a favor by not linking to overcomingbias.com

I get unsolicited email offering to genetically modify rats to my specifications.

I guess this is evidence that we live in a sf novel. Thanks to spam the world's most powerful supercomputer cluster is now run by criminals: http://blog.washingtonpost.com/securityfix/2007/08/storm_worm_dwarfs_worlds_top_s_1.html Maybe it is by Vernor Vinge. Although the spam about buying Canadian steel in bulk (with extra alloys thrown in if I buy more than 150 tons) might on the other hand indicate that it is an Ayn Rand novel.

This whole issue seems to be linked to the question of how predictable the future is. Given that we get blindsided by fairly big trends the problem might not be lack of information nor the chaotic nature of the world, but just that we are bad at ignoring historical clutter. Spam is an obvious and logical result of an email system based on free email and a certain fraction of potential customers for whatever you sell. It ought to have been predictable in the earliest 90's when the non-academic Net was spreading. But at the time even making predictions about the economics of email would have been an apparently unrewarding activity, so it was ignored in favor of newsgroup management.

Maybe the strangeness of the future is just a side effect of limited attention rather than limited intelligence or prediction ability. The strangeness of the past is similarly caused by limited attention to historical facts (i.e. rational ignorance, who cares to understand the victorian moral system?), making actual historical events look odd to us (Archduke Franz Ferdinand insisted on being sewn into his clothes for a crease-free effect, which contributed to him dying and triggering WWI).

Since this is overcomingbias, it might be useful that when presenting our narratives of past vs. present, it might be useful to watch out for narratives invoking an inevitability of progress.

All of Eliezer's 3 points from the past seem to touch on that: (1) new scientific knowledge, (2) improved technology, and (3) more social acceptance and opportunities for power minorities.

"I could believe in the spanking thing happening pretty easily. "

Don't forget, Singapore's reliance on caning brings revulsion from the kind of person who thinks of prisons as cruel.

-dk

Given that WWII showed that race could be dynamite, it's surely astonishing that so many rich countries have permitted mass immigration by people who are not only of different race, but often of different religion. Even more astonishing that they've allowed some groups to keep immigrating even after the early arrivers from those groups have proved to be failures, economically or socially. Did anyone predict that 60 years ago?

Some say we did elect a partly black Prez in 1920 -- Warren Harding.

dearieme: "Given that WWII showed that race could be dynamite, it's surely astonishing that so many rich countries have permitted mass immigration by people who are not only of different race, but often of different religion. Even more astonishing that they've allowed some groups to keep immigrating even after the early arrivers from those groups have proved to be failures, economically or socially. Did anyone predict that 60 years ago?"

I thought that the excessive tolerances and the aversion to distinguish groups of people based on factual differences are traits that developed as a result of oversensitization from the events of WWII. Hitler's people engaged in cruel and unjust discrimination, so all discrimination is now cruel and unjust. Hitler's people (and others before them) engaged in cruel and gruesome eugenics experiments, so all eugenics are cruel and gruesome.

If Hitler did cruel experiments using pasta, pasta would now be known to be bad for everyone.

Actually, the last statement (about spankings instead of jails) doesn't sound foolish at all. We abolished torture and slavery, we have replaced a lot of punishments with softer ones, we are trying to make executions painless and more and more people are against death penalty, we are more and more concerned about the well-being of ever larger groups (white men, then women, then other "races", then children), we pay attention to personal freedom, we think inmates are entitled to human rights, and if we care more about preventing further misdeeds than punishing the culprit, jails may not be efficient. I doubt spanking will replace jail, but I'd bet on something along these lines.