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Comment by antognini | Hacker News Reader

There is a very old theory called the "Tired Light Hypothesis" which supposes that for some unknown reason light loses energy as it travels over cosmological distances. This would reproduce the observed redshifts, but it has issues predicting pretty much every other cosmological observation.

In particular it doesn't explain observed reductions in surface brightness (expansion has the effect of "defocusing" collimated light). And it doesn't explain observed time dilation effects.

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I've always wanted to play a game based on defunct theories. I'm a fan of luminiferous aether myself. What are the impacts on a spacefaring civilization?

Sci-fi already grants alternative physics to enable FTL and other magic. What about hard sci-fi, but wrong-hard sci-fi?

Extra credit: go back to Zeno and all motion is paradoxical, what would you even do in the game?

If you haven’t read Greg Egan’s Orthogonal Trilogy, you might like it. https://en.m.wikipedia.org/wiki/The_Clockwork_Rocket

It feels like all space combat games I've seen rely on Aristotle's theory that objects prefer to be at rest.

Try Frontier: Elite II if you want to try a "realistically modeled" view of space combat - things are pretty much strictly Newtonian.

Terminus seemed to have pretty decent physics too, but it's been a long time.

Children of a Dead Earth is my suggestion https://store.steampowered.com/app/476530/Children_of_a_Dead...

Not space combat ... Flight Of Nova

> Flight of Nova is a simulator based on newtonian mechanics in which you control spacecraft in the Noren star system. You fly multiple types of spacecraft doing transport and search missions in an environment with realistic aerodynamics and orbital physics.

https://www.youtube.com/@flightofnova5746

And in old Trek it seemed that if the engines ever lost power the ship was in danger of deorbiting and crashing within hours for some reason.

My theory was always that ships hardly ever orbited unpowered, they usually went into much lower powered "orbits" or even just hovered "in place" using the (immense) power of their engines.

But to fly so low as to slow the ship down if unpowered, they'd generate enormous heat from atmospheric friction. They could use shields but then the ship would glow, alerting the natives below and violating the Prime Directive. And they called it "standard orbit".

Orbiting doesn't require power. Even a satellite in a very low orbit only needs a slight boost once in a while to counter the drag.

There's no reason for the shields to cause friction though. They're not made of ordinary matter so an extended, very angular shield could probably cut through atmosphere seamlessly.

Maybe they need a very low orbit to keep the planet's surface in range of the transporters.

Nice try, but:

"According to The Original Series (TOS) writers' guide, the effective range of a transporter is 40,000 kilometers."

https://en.wikipedia.org/wiki/Transporter_(Star_Trek)

Yeah, but maybe that's the maximum range when conditions are best. Much of the time, if there's an equipment problem called for in that episode, there's some issue with the planet's atmosphere ("electromagnetic storm" or similar) which causes trouble with the transporters.

They're usually in geosynchronous orbit over the interesting area of the planet. That requires power to maintain if you're not just staying over the equator. Even over the equator it only works without power at a certain altitude.

Luminiferous aether in what sense, what physics? Relativity doesn't exactly disprove it, it shows that everything distorts in a way that would make any aether unmeasurable. So if you just say aether:yes by itself I don't think anything happens.

> This would reproduce the observed redshifts, but it has issues predicting pretty much every other cosmological observation.

Not to mention contradicting the laws of conservation of energy and momentum.

To be fair we do already know that energy is not globally conserved over cosmological timescales. (Energy conservation is a consequence of time invariance, but cosmological expansion breaks that symmetry.)

Fritz Zwicky attempted to propose a mechanism of tired light that was caused by Compton scattering off of the intergalactic medium. But these kinds of scattering mechanisms produce far too much blurring in the expected images of distant galaxies and galaxy clusters.

> To be fair we do already know that energy is not globally conserved over cosmological timescales.

No, what we know is that there is no invariant global concept of "energy" at all except in a special class of spacetimes (the ones with a timelike Killing vector field), to which the spacetime that describes our universe as a whole does not belong.

However, "tired light" (at least the versions of it that aren't ruled out the way the Zwicky model you describe was) violates local energy-momentum conservation, which is a valid conservation law in GR (the covariant divergence of the stress-energy tensor is zero).

That is a good clarification.

Somehow I learnt about Riemannian manifolds and Killing vector fields in a geometry class that didn't mention physics at all.

I am always entertained when some nonsense I learned actually has something to do with the real world.

I like your theory more than the current setup.

I have an interesting addition to it:

Time dilation could be that going very fast in the space makes you relatively faster in one direction.

The thing is, atoms also have to travel; so the atoms (and matter in general) have a slightly longer distance to travel, to achieve the same chemical reaction. Which means interactions between atoms is slower, giving illusion of a slower time due to slower inter-atoms reactions.

I don’t think this would match the observations that can be made from earth of things on earth?

Though the phrasing seems a bit ambiguous. Could you put some math behind those words?

I think you just described relativity from the perspective of atoms. It's still the same old relativity though.

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