Is The Speed Of Light The Ultimate?

[hiflier]

Is it true that on/in the sun the speed of sound is greater than the speed of light? If so, how can this be if the speed of light cannot be exceeded by anything. OK, so no object is moving at either of these speeds but if true it does imply that information can be transmitted at a greater speed by sound than by light (or radio or any other electro-magnetic radiation), meaning in turn that cause and effect might be reversed.

[TheChair]

"Is it true that on/in the sun the speed of sound is greater than the speed of light?"
No.
The speed of light is 299 792 458 m / s, the speed of sound on the surface of the sun is around 10,290 m / s.

[ivor4781]

easier to say, approx-- light 186.000 miles per second --- sound 750 miles per hour

[jim360]

It's worth pointing out that light doesn't always travel at the maximum speed of light, so there are occasions that sound will travel faster than light through something. I think that inside the Sun might even be one of these cases, as I've read somewhere that photons of light can take some thousands of years to go from the centre of the Sun to the outside (and then only minutes to get to the Earth from then).

In that case sound *does* travel faster than light in the sun. But that's nothing to do with information transfer, or cause and effect etc. Sound also travels faster than light through a solid wooden door, but information still reaches you no faster than the *in vacuum* speed of light.

So, in short, whether or not light travels slower inside the Sun than sound does, Sound is still stuck at slow speeds compared to the speed of light in vacuum. Hence causality isn't affected by this argument.

[Old_Geezer]

Meanwhile there seems to be discussion/debate over whether the maximum speed of light was higher in the past. Now that's a thought, light going faster than the speed of light. Judging by Superman's abilities, does than mean time went backwards in the past ? In which case what was the date when time stood still ?

[jim360]

I don't think that's what the idea would mean, OG. The speed of light would always remain the maximum speed limit -- it's just that said limit would change with time. The same laws of Physics, in particular of Special Relativity, would still hold other than that change.

[Old_Geezer]

:-D
Whoosh ?
;-)