Why Is Everything in Space Moving So Fast?

[Lucas_Jackson]

@kayaker

“Sure, driving through that school zone at 85 it seemed like I was going fast, but I’d like you to consider things on a universe scale, your honor.”

Brilliant!

[Mangetout]

It’s not moving fast. You are.

[Exapno_Mapcase]

@Machine_Elf

Everything on earth is moving very slowly because if it weren’t, it would burn up in the atmosphere. Novelty Bobble nailed it in the first response: the universe has a whole histogram of speeds, and our experience is only with the very very slow end of that histogram, so anything off-earth is going to seem like it is moving very fast - but only compared to our prior experience.

But the atmosphere itself is moving very fast. The earth rotates at about 1000 mph at the equation and about 700 mph in the temperate zones. We don’t feel that because we too are moving at that speed on the surface of the Earth. Our default speed is a gigantic number that took 99.9999+% of the Earth’s history for us to replicate.

We only feel the difference between that default speed and any additional velocity. Meteors that pass through the atmosphere are moving at tens of thousands of mph. That’s why they burn up: the difference between that and 1000 is still huge.

[DSYoungEsq]

Most things in space are NOT moving fast. Think of the scale. Even light, which moves faster than anything else, takes for freakin’ ever to get from place to place in the universe. Planets and suns and even galaxies move very, very, VERY slowly, given the space through which they are moving.

The only reason all these things seem to be moving quickly to us is that we move extremely slowly on that scale. Even on the scale of our planet, we moved very slowly until we managed to come up with rocket engines.

Think about looking down at a small river, flowing along at a mild pace. The river’s water moves relatively slowly, taking days and days to get from one end to another. But if we zoom in on small portions of the river, we see things like eddies, where the water, on that much smaller scale, seems to be moving fast as it circulates around. To the little, insignificant speck of algae in that water, everything would seem to be going at breakneck speed. That’s us: the insignificant algae of space.

[joema]

@Machine_Elf

…Novelty Bobble nailed it in the first response: the universe has a whole histogram of speeds, and our experience is only with the very very slow end of that histogram, so anything off-earth is going to seem like it is moving very fast - but only compared to our prior experience.

Yes, the question could likewise have been “why is everything in space so far away?”. Energies, distances and forces of the universe are far beyond everyday human experience. As Dr. Morbius said in Forbidden Planet, “Prepare your minds for a new scale of physical scientific values”.

However it also works in the opposite direction: you could also ask why is the atom so small?

These contrasts with normal human experience were covered in the classic educational short film, “Powers of Ten”: https://www.youtube.com/watch?v=0fKBhvDjuy0