A civilization has begun its space program without any knowledge of general or special relativity. How would this affect the program? Would this establish any limits on where/how they could travel? Could they make it to the moon or other planets? Would space travel be possible at all? Finally, if this is possible, how helpful would it be in the eventual discovery of relativity?

Edit: Their current understanding of physics is the same as ours just before relativity.

  • $\begingroup$ So you're looking at a technology level equivalent to about WW1 era? $\endgroup$ – Arkenstein XII Nov 12 '19 at 3:04

They could absolutely get to space. "Rocket science" isn't a complex field of science: it's just ballistics and some straightforward chemistry. What's fiendishly complex is the precision engineering and manufacturing required to go, not just into space, but where you mean to go with very little margin for error.

What this means is that initially your numbers would all be wrong. If you do calculations in a fast-moving environment without taking relativity into account, you end up with numbers that are somewhat different than the true numbers. Your scientists would discover that their rockets, their clocks, everything functioned slightly different than projected.

This sounds bad - a small difference in propulsion is the difference between making it to the moon and crashing into it, or flying off into empty space, never to see Earth again. But the reality is that in space exploration, nothing works quite like you projected it would the first time. The history of space is replete with experiments, tests, and incremental refinement of ideas. The first of anything rarely performed according to the models, but would show us where the models were wrong so we could fix them.

The same would happen with your engineers: they would be able to measure and eventually predict this effect, and would discover that it was tied to the velocity of the object in question. Once they learn to account for the variations, they can run the same calculations that we can, arrive at the same numbers for impulse, velocity, flight time, etc. They can adjust their clocks to deal with minute variations when at speed. Their ability to operate in space won't be impaired.

You could make a fair case that they have discovered relativity then: they can describe perfectly what it does, they just don't know why (or rather, can't describe "why" in relation to their other physical theories). There are plenty of phenomena that we're at this stage with in real life, little things like gravity. It doesn't stop them (or us) from working with these unknowns.

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    $\begingroup$ They might come up with some extremely complex compensation tables if no one proposes the underlying relativity theory. It is an open question just how unique Einstein was to make the mental breakthrough that lead to his “miracle year”. $\endgroup$ – SRM Nov 12 '19 at 3:54
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    $\begingroup$ @SRM Before we had computers up to the task, "some extremely complex tables" is basically how plotting and navigation were done. At least they'd be on familiar ground. $\endgroup$ – Cadence Nov 12 '19 at 3:57
  • $\begingroup$ @SRM There was a considerable amount of scientific effort expended on the ideas that became special relativity. There were lots of approximations of what became SR. Einstein, and Henri Poincare, worked out how to put it together at about the same time. Einstein was lucky. The journal he submitted his paper to, had a better publication schedule and he was published first. The term "relativity" was coined by Poincare. It was the cluster of Einstein's discoveries that makes his miracle year the miracle. Few have had it so good. $\endgroup$ – a4android Nov 12 '19 at 4:55
  • $\begingroup$ @a4android agreed... I’m simply noting the possibility that they could do a lot of empiric work and still not hit on relativity. Relativity is fairly counterintuitive compared to, say, F=ma. $\endgroup$ – SRM Nov 12 '19 at 13:24

Relativity becomes significant for either very large masses or very high velocity.

No big impact until they deploy the equivalent of our GPS satellite network, or start equipping satellites with very precise clocks.

At that point they will notice that clocks on the ground and clocks high up in space will measure different times.

But nothing dramatic preventing rockets to go up and fast in the sky.

Even in our history, rockets have been studied before Einstein came up with relativity.

William Leitch first proposed the concept of using rockets to enable human spaceflight in 1861. Konstantin Tsiolkovsky later (in 1903) also conceived this idea, and extensively developed a body of theory that has provided the foundation for subsequent spaceflight development.


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