speed of light?

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Discussion

danwins

Original Poster:

73 posts

177 months

Sunday 26th June 2022
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Evening all.

Just had a good debate with my daughter and thought I'd get your input.

We all know you cant travel faster than light for various reasons, Mass, time etc, but my daughter put up a valid question. Hundreds of years ago we proved everything revolved around the earth,we were wrong, we proved we were the center of the galaxy, we were wrong again... so on and so on. Science is always proving then disproving theories So is there a possibility in a few hundred years we could be wrong about traveling faster than light?

Dan

Super Sonic

4,515 posts

53 months

Sunday 26th June 2022
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It is possible, but to say that it will is pure speculation. Experiments have proved they relativity is real, and that time slows down the faster something moves. At the speed of light, time is reckoned to stop. There is also the energy required to accelerate something, and iirc, to accelerate something to c would need all it's mass to be turned to energy.
The nature of science, though, is such that things are only true until proved otherwise, it's called 'falsifiability'.

eldar

21,614 posts

195 months

Sunday 26th June 2022
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The Tachyon. Faster than light, perhaps.

https://en.wikipedia.org/wiki/Tachyon

annodomini2

6,860 posts

250 months

Sunday 26th June 2022
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Accurately measuring the speed of light is impossible, what we have this far is an average.

If there is any differential behaviour in the speed of light it's impossible to measure due to relativity.

For now based on our current observations general relativity stands at that scale, is it 100% correct, no. It currently falls apart at quantum scales and there are still big questions it currently cannot be answered (dark matter, dark energy).

Will our understanding improve over that time if we are still around, probably.

Will it change the speed of light situation, current observations say unlikely, but not impossible.

lrdisco

1,441 posts

86 months

Sunday 26th June 2022
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Great question.
Asked my son who is studying Astro physics and physics at Uni and his responses was- Dad you have no idea what the question even is.

aizvara

2,050 posts

166 months

Sunday 26th June 2022
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annodomini2 said:
Accurately measuring the speed of light is impossible, what we have this far is an average.
I'm probably being stupid/misunderstanding what you said, but I thought we defined all SI units around the speed of light and planck time/distance, so there is no measurement of the speed of light, it is a constant.

ChocolateFrog

24,852 posts

172 months

Sunday 26th June 2022
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I'm pretty sure there are ways of travelling faster than light without breaking the laws of physics

If 2 objects are far enough apart then are they not moving faster than the speed of lof light relative to each other? I.e. you could set off faster than the speed of light towards the other object and it would still be moving away from you.

67Dino

3,581 posts

104 months

Sunday 26th June 2022
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I find it’s easier to think of the speed of light differently to the speed of anything else.

I think it’s easier to think of it as a measure of the speed of “now”, the rate at which the current moment moves through the Universe. Nothing can cause anything else to happen faster than the speed of light travelling the distance (entanglement aside, another matter).

So whilst it takes light 8 minutes to get to us from the sun, the photon itself hasn’t spent any time at all. As far as it’s concerned, the moment it left the sun and the moment it arrived at Earth were the same moment.

It is often said that we are seeing the stars in the sky as they were thousands or millions of years ago, but personally I think this is confusing matters, since “now” only moves at the speed of light. It’s really meaningless to create a different sort of simultaneity where time is the same there as here, as that doesn’t exist.

Just aswell really, as if everything happened at the same time everywhere, we’d be blasted by every supernova going, regardless where it was.

HTH.

Ayahuasca

27,427 posts

278 months

Sunday 26th June 2022
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If I shine a laser at a large object a long way away, say Jupiter, and then quickly move the laser along Jupiter’s equator from one side to the other, the dot of light can travel faster than light.

Gnits

915 posts

200 months

Sunday 26th June 2022
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I think the issue here is the initial premise. Nobody 'proved' the earth was at the centre of the galaxy/solar system/universe. Proof is for the mathematical domain.
The accepted model may have been that the earth was the centre of the solar system but it was just a model and over time the models change to make them more accurate. Although to be fair we still use older models or approximations for convenience on a number of occasions, gravity being a prime example.
The speed of light will change depending on the medium it passes through, the current model of the fastest this stuff goes depends on it being in a vacuum and normally this is the case space being, well, rather empty. However we all know this model can be improved, it breaks down in certain areas so we can expect this to be updated at some point.

Super Sonic

4,515 posts

53 months

Sunday 26th June 2022
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Ayahuasca said:
If I shine a laser at a large object a long way away, say Jupiter, and then quickly move the laser along Jupiter’s equator from one side to the other, the dot of light can travel faster than light.
It's not the same dot.

Fusion777

2,211 posts

47 months

Monday 27th June 2022
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Ayahuasca said:
If I shine a laser at a large object a long way away, say Jupiter, and then quickly move the laser along Jupiter’s equator from one side to the other, the dot of light can travel faster than light.
The “dot” isn’t a physical object though. You’re just seeing the result of illuminating different spots with radiation. There is no object that moves from one side of the planet to the other, we just interpret visually that there is.

As said earlier, we never proved that the earth was at the center of the solar system or galaxy, it was just supposed that it was based on observation of stars etc.

The speed of light can be and is measured very accurately, by the way.

Might post something longer when I don’t have to get ready for work…

llewop

3,585 posts

210 months

Monday 27th June 2022
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Chernekov radiation - faster than speed of light in a medium (such as water). So the blue glow you see around reactor cores/high activity sources under water.

I'm not enough of a physicist to follow all in the wiki page on it, so good luck!

What I do know though is that it is an absolutely stunning thing to see (from the safety of above the several metre deep pool...)

Dr Jekyll

23,820 posts

260 months

Monday 27th June 2022
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eldar said:
The Tachyon. Faster than light, perhaps.

https://en.wikipedia.org/wiki/Tachyon
A tachyon is faster than light by definition, but that doesn't add anything to the debate any more than the definition of unicorn tells us whether there are any horses with horns.

Simpo Two

85,148 posts

264 months

Monday 27th June 2022
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danwins said:
Evening all.

Just had a good debate with my daughter and thought I'd get your input.

We all know you cant travel faster than light for various reasons, Mass, time etc, but my daughter put up a valid question. Hundreds of years ago we proved everything revolved around the earth,we were wrong, we proved we were the center of the galaxy, we were wrong again... so on and so on. Science is always proving then disproving theories So is there a possibility in a few hundred years we could be wrong about traveling faster than light?

Dan
The explanation I had at school was that the closer something gets to 'c', the more energy is required to accelerate it. At 'c' that energy requirement becomes infinite. Hence 'c' is the limit beyond which you cannot go.

Of course we said the same thing about the speed of sound, but we have more physics and knowledge now.

The only answer I can think of to exceed 'c', or shall we say to get to the destination faster, is to bring the destination closer. And you do that by warping space. So far the only thing that can do that is gravity, I think.

Ayahuasca

27,427 posts

278 months

Monday 27th June 2022
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Or by stepping though a wormhole into a parallel universe that happens to be identical, but xxx light years away in the old universe.

Wacky Racer

38,099 posts

246 months

Monday 27th June 2022
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Given that the speed of light is 186,000 miles per second, and the sun is 93 million miles away.

Am I right in assuming that when you look up to the sun you don't see it as it is now, but how it was eight minutes before?

nerd

deckster

9,630 posts

254 months

Monday 27th June 2022
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Wacky Racer said:
Given that the speed of light is 186,000 miles per second, and the sun is 93 million miles away.

Am I right in assuming that when you look up to the sun you don't see it as it is now, but how it was eight minutes before?

nerd
Yes. Which is why it's so interesting for us to observe objects that are 13 billion light years away; it's not so much that they're a long way away, it's more than we genuinely are seeing things which happened just after the universe began. In a very literal sense, viewing very far away objects is actually looking at the past.

alock

4,224 posts

210 months

Monday 27th June 2022
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If a photo travels at the speed of light, and time stands still at the speed of light, is there more than one photo in the entire universe?

wobble

Dr Jekyll

23,820 posts

260 months

Monday 27th June 2022
quotequote all
Simpo Two said:
The explanation I had at school was that the closer something gets to 'c', the more energy is required to accelerate it. At 'c' that energy requirement becomes infinite. Hence 'c' is the limit beyond which you cannot go.

Of course we said the same thing about the speed of sound, but we have more physics and knowledge now.

The only answer I can think of to exceed 'c', or shall we say to get to the destination faster, is to bring the destination closer. And you do that by warping space. So far the only thing that can do that is gravity, I think.
We never said that about the speed of sound, it's just that there are certain engineering challenges in making an aircraft that can exceed Mach1 without disintegrating or going out of control.