this post was submitted on 25 Jul 2024
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I can whistle at the speed of sound (sh.itjust.works)
submitted 3 months ago by [email protected] to c/[email protected]
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[–] [email protected] 78 points 3 months ago (3 children)

I mean, any other non-c speed really.

[–] [email protected] 15 points 3 months ago (1 children)

I would be especially interested in speeds larger than c πŸ™‚

[–] [email protected] 13 points 3 months ago* (last edited 3 months ago)

[–] [email protected] 103 points 3 months ago (3 children)

Actually, c is the speed of light in a vacuum, but light travels slower through a medium, like air. So lasers shot through air will actually travel slower than c.

[–] [email protected] 7 points 3 months ago (1 children)

A laser strong enough to be used as a weapon will probably not leave a lot of medium on its path.

But the front-most part will still travel at less than c. It will just speed-up after a while.

[–] [email protected] 1 points 3 months ago (1 children)

I'm curious. What happens to the medium? Does it simply get pushed aside? Or pushed along? Or will it eat up some energy and react to something else?

[–] [email protected] 6 points 3 months ago

Much like lightning, a powerful enough laser will ionize the air. That ionized air is hot and rises, just like the ionized gasses from combustion.

A powerful laser will look like a beam of fire.

[–] [email protected] 58 points 3 months ago (2 children)

(For anyone curious, the speed of light in earth air is like 99.97% as fast as in vacuum)

[–] [email protected] 22 points 3 months ago (2 children)

Bunch of nerds in this thread.

[–] [email protected] 6 points 3 months ago

exactly where they should be.

[–] [email protected] 15 points 3 months ago (1 children)

You're in science_memes what did you expected?

[–] [email protected] 3 points 3 months ago (1 children)

hot science girls

[–] [email protected] 2 points 3 months ago (1 children)

Where?

[–] [email protected] 4 points 3 months ago

In your area

[–] [email protected] 5 points 3 months ago

Ya, but that's JUST slow enough to be able to see it.

[–] [email protected] 15 points 3 months ago (1 children)

Maybe it's going to be space lasers.

[–] [email protected] 34 points 3 months ago (2 children)

Do you know what the religious affiliation of these space lasers will be?

[–] [email protected] 21 points 3 months ago (1 children)

You have a lot of chutzpah to ask such a question. Oy! What would your mother say?

[–] [email protected] 6 points 3 months ago

β€œYou’re so skinny why are you not eating”

[–] [email protected] 12 points 3 months ago (1 children)

Flying Spaghetti Monster

[–] [email protected] 10 points 3 months ago (3 children)

Well that's pretty easy, just fire it anywhere except a vacuum.

[–] [email protected] 1 points 3 months ago (1 children)

It's still travelling at c, it's just bouncing around the medium's particles on the way. It arrives later because it's not going in a straight line.

[–] [email protected] 4 points 3 months ago* (last edited 3 months ago) (1 children)

I don't think that's a great way of thinking about it. I think you're describing something more like scattering

or maybe absorption and stimulated or spontaneous emission

which does indeed happen, but is distinct from the index of a medium.

If it were indeed "bouncing," optics wouldn't really work, as any n > 1 medium would cause the light to go every which way.

[–] [email protected] 2 points 3 months ago (1 children)

If you fire a laser that goes first through vacuum, then through a lens, then again in vacuum, at what speed is the light travelling on the other side?

[–] [email protected] 1 points 3 months ago (1 children)

It's same as it was at first. The speed of light depends on the index of refraction of the medium it's in, but doesn't depend on its "history."

[–] [email protected] 2 points 3 months ago (1 children)

I didn't write it out, but what I was trying to get at was that if it would "slow down", then it would be slower on the other side. The explanation that the light travels longer through a medium with the same speed would therefore make sense to me.

But then again, how it wouldn't shoot out in every direction, that doesn't make sense to me.

I don't know much about light, that's why i'm asking. And i'm sure some article or paper would have anwers for that question, I might search it on my own.

[–] [email protected] 2 points 3 months ago

Ah, I think I see what you mean.

I think the right way to think about this is as a wave, and in that respect, it's no different from sound waves. If sound goes through the air, then through another medium, then out the other side back to air, the speed will follow the same general rules as with light. One notable differece is that speed of sound through many materials is faster than through air.

Note also that you'll get acoustic reflections at interfaces, which is analogous to optical (Fresnel) reflections at interfaces (e.g., reflection off of glass or water).

[–] [email protected] 2 points 3 months ago

Yes, ofc - but we're talking about a weapon here, the air is implied as a medium, and the very-near-c with it.

But a weapon that would construct some sort of structure or a tunnel between it's position and the target would be something else indeed.

[–] [email protected] 11 points 3 months ago

But I never use my vacuum. Might as well fire a laser at it!