Suppose I told you that I knew for a fact that the following statements were true:
If you paint yourself a certain exact color between blue and green, it will reverse the force of gravity on you and cause you to fall upward.
In the future, the sky will be filled by billions of floating black spheres. Each sphere will be larger than all the zeppelins that have ever existed put together. If you offer a sphere money, it will lower a male prostitute out of the sky on a bungee cord.
Your grandchildren will think it is not just foolish, but evil, to put thieves in jail instead of spanking them.
You’d think I was crazy, right?
Now suppose it were the year 1901, and you had to choose between believing those statements I have just offered, and believing statements like the following:
There is an absolute speed limit on how fast two objects can seem to be traveling relative to each other, which is exactly 670,616,629.2 miles per hour. If you hop on board a train going almost this fast and fire a gun out the window, the fundamental units of length change around, so it looks to you like the bullet is speeding ahead of you, but other people see something different. Oh, and time changes around too.
In the future, there will be a superconnected global network of billions of adding machines, each one of which has more power than all pre-1901 adding machines put together. One of the primary uses of this network will be to transport moving pictures of lesbian sex by pretending they are made out of numbers.
Your grandchildren will think it is not just foolish, but evil, to say that someone should not be President of the United States because she is black.
Based on a comment of Robin Hanson’s: “I wonder if one could describe in enough detail a fictional story of an alternative reality, a reality that our ancestors could not distinguish from the truth, in order to make it very clear how surprising the truth turned out to be.”1
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).
Suppose I told you that I knew for a fact that the following statements were true:
You’d think I was crazy, right?
Now suppose it were the year 1901, and you had to choose between believing those statements I have just offered, and believing statements like the following:
Based on a comment of Robin Hanson’s: “I wonder if one could describe in enough detail a fictional story of an alternative reality, a reality that our ancestors could not distinguish from the truth, in order to make it very clear how surprising the truth turned out to be.”1
1Source: http://lesswrong.com/lw/j0/making_history_available/ewg.