In “Descartes’ Bones”, the book we are reading for this month’s meeting, the author seems to blame Descartes for moral relativism which makes me nervous because I figure that an assault on secularism is coming next - and I have been enduring that crap all my adult life.

However, it is interesting, the relativity thing.

Galileo posed the first scientific theory of relativity. He said that all uniform motion is relative - no absolutes. For example, if you’ve got one spaceship in an otherwise empty universe there is no way you can say the spaceship is moving or not (unless it is moving in a nonuniform manner). If you add another spaceship moving relative to the first, the only thing you could say is that there is relative motion between the two - not whether one or both are moving or one (but not both) are standing still.

Another example is when two trains pass one another on nearby tracks. If the motion is smooth and uniform you have a hard time telling if it’s your train or the other that is moving (or if it is both).

Not having a fixed frame of reference can be pretty disorienting which might explain why some people are so disturbed by moral relativism. However it should be noted that Galileo’s relativism was part of a theory which said that if the laws of mechanics are valid in one coordinate system (stuff moving together in uniform manner) they are also valid in another coordinate system (other stuff moving in a uniform manner in another direction or speed). In his theory Galileo preserved a larger absolute - the laws of mechanics. He ensured that the universe stayed sane.

Einstein did the same thing when he extended Galileo’s theory to include all the laws of physics - including electromagnetic phenomena like light and radio waves. The problem was that in the decades prior to the time Einstein wrote his Special Theory of Relativity, the speed of light had been proven to be the same regardless of the motion of the source. In some clever thought experiments Einstein showed that this meant that no object could be measured exceeding the speed of light.

That’s when things got weird. Replacing the simple Galilean formulas used to transfer measurements between coordinate systems with more complex transformation rules, Einstein described a strange new universe. Relative to an outside observer, the faster you go, the more your clock slows down, mass increases and length shrinks.

However, like Galileo, Einstein was ensuring that the universe stays sane. If objects could exceed the speed of light, events could precede causes and things could get seriously out of whack. Both men restricted personal claims to knowledge in order to preserve larger, universal absolutes.

I don’t know if this has any bearing on Descartes and moral relativism - but it is an interesting point. Maybe next time.

Here are a couple of crude little videos illustrating some of these points:

Other such videos can be see on the bog "Einstein - Evolution of Physics".

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