Why light speed is constant?

[Mellinia]

When light passes a large body in the universe the gravity of the said mass causes the light to bend and curve around the mass.

 

so in theory the light adjacent to the light that has just curved around the mass will be travelling faster as the curved light has travelled a greater distance.

 

so there for one or the other would have had to of travelled at a different speed,

 

its not possible for some thing travelling at a constant to cover a greater distance eg the straight line is say 500.000miles and the curved line is 510.1740 miles.

 

how can something with the same speed and velocity cover two different distances at the same time and speed QED

 

 

 

But the reason why light is curved is because spacetime is curved so that light speed is constant....to light, there is no curve, to us, there is...

[Sorcerer]

All measurements of the speed of light have been constant. The notion of a speed of light "decay" is an old creationist attempt to explain away the age of the universe as given by redshift measurements of distant galaxies

 

Well who cares what they think, but u shouldn't just dismiss an idea because some idiot was using it for the wrong reasons.

 

I was thinking about this and wouldn't a change in the speed of light allow alternate, and perhaps more simple explanations for inflation and dark energy?

Edited December 21, 2011 by Sorcerer

[swansont]

I was thinking about this and wouldn't a change in the speed of light allow alternate, and perhaps more simple explanations for inflation and dark energy?

 

But there are other implications. You can't tug on one area of physics without changing it elsewhere. You "solve" one problem and cause dozens of others.

[Sorcerer]

Shows how sensitive occam's razor is when it comes to complex things.

 

Swansont I don't disagree, I wasn't actually afirming anything.

Edited December 21, 2011 by Sorcerer

[JustinW]

All measurements of the speed of light have been constant. The notion of a speed of light "decay" is an old creationist attempt to explain away the age of the universe as given by redshift measurements of distant galaxies

 

Yes, I stand corrected. What I was trying to recall was about photons reacting with other material, not about speed in a vacuum. I don't know if creationalists had anything to do with it though, and I don't recall any mention of red shifts either.

[michel123456]

See also The varying speed of light cosmology

[JustinW]

Thanks for the link. It made me remember a few questions I've had in the past. I find it weird, to say the least, that light slows down through a medium but once out of the medium continues at it's origional speed. Does anyone know why? I've found it a little hard to grasp and asked myself how it could be propelled back to the origional speed without some outside influence affecting its increase in velocity and frequency.

 

Also, if a photon has no mass, why would a medium have any affect on it at all? I understand that a medium might have an affect on its frequency, but doesn't a frequency constitute having mass in the first place? Doesn't a frequency come from the oscillations of mass-having objects?

Edited December 21, 2011 by JustinW

[imatfaal]

Thanks for the link. It made me remember a few questions I've had in the past. I find it weird, to say the least, that light slows down through a medium but once out of the medium continues at it's origional speed. Does anyone know why? I've found it a little hard to grasp and asked myself how it could be propelled back to the origional speed without some outside influence affecting its increase in velocity and frequency.

 

Also, if a photon has no mass, why would a medium have any affect on it at all? I understand that a medium might have an affect on its frequency, but doesn't a frequency constitute having mass in the first place? Doesn't a frequency come from the oscillations of mass-having objects?

 

The simple heuristic is that the photon travels between interactions at the speed of light but in any medium it will also interact with the particles of that material. and when interacting with the atoms of the material the photon is absorbed and re-emitted which takes time. ie when travelling the speed is c - but the progress of the beam is slowed by the time of the interactions

[JustinW]

The simple heuristic is that the photon travels between interactions at the speed of light but in any medium it will also interact with the particles of that material. and when interacting with the atoms of the material the photon is absorbed and re-emitted which takes time. ie when travelling the speed is c - but the progress of the beam is slowed by the time of the interactions

Yes that makes sense. But you would think, or this is just my simpllistic way of thinking, that to have any interaction at all, it would have to hold mass to some degree. And how does anyone explain light frequency if there is no mass oscillation to create one?

[Sorcerer]

Yes that makes sense. But you would think, or this is just my simpllistic way of thinking, that to have any interaction at all, it would have to hold mass to some degree. And how does anyone explain light frequency if there is no mass oscillation to create one?

 

Matter absorbs the light at certain wave lengths, it doesn't need mass it has/is energy (E=mc^2). The light is then emited again. Electrons can move between shells using photons, when they lose that photon they jump down a shell and floresce. Hence glow in the dark materials/minerals.