Thread: Light Slowing Down = Light Pileup?

If light is slowing down, as some scientists seem to be advocating, then won't be be dealing with more concentrated light in the future?

Now, light moves so fast. But if it slows down, won't it get alot more concentrated? Especially when reflection occurs?

Originally Posted by FalconX2000

If light is slowing down, as some scientists seem to be advocating, then won't be be dealing with more concentrated light in the future?

Now, light moves so fast. But if it slows down, won't it get alot more concentrated? Especially when reflection occurs?

This all is not as unusual as you imply. The "concentration of light" you mention is measured by the intensity or flux density, which is the number of photons per time unit and area unit it passes. A laser, e.g., has a very high photon density. It can even be so high that two photons can interact to produce a photoelectric effect of their combined energy.

However, light has always the same velocity, as long as it stays in the same medium with the same refractive index. There are well known physical phenomena accompanied with light moving between different media. The best known effects are refraction, dispersion and total reflection. The latter is used in fibre optics, where the light stays within the fibre regardless of its bending.

A well known physical device, where a high photon density is produced by multiple reflection between two parallel glass plates is the Fabry-Perot interferometer. The photons interfere and produce a highly resolved spectrum.

Another interesting and related physical effect is the Cerenkov radiation. It is produced by particles (mostly electrons) that have been accelerated to a velocity that is higher than the speed of light in the medium they are flying into. This produces a shock similar to the sonic booms of a plane exceeding the speed of sound.

Glass and other things can slow light down. It ALL slows down so you might say it is more concentrated inside glass, but as soon as light leaves glass, it goes back to it's normal speed (in air). Since it is a reversal of what happened on the way in, no difference is noticed. A Bose Einstein Condensate (all particles moving uniformly) can even stop light but only so much light and as soon as the BEC disappears, the light resumes it's normal speed.

Thanks, but I am still unsure about the theorised decay of the speed of light. Would that mean that, barring other forces interfering, things would get brighter on Earth in the future?

Originally Posted by FalconX2000

Thanks, but I am still unsure about the theorised decay of the speed of light. Would that mean that, barring other forces interfering, things would get brighter on Earth in the future?

If you are thinking of a cosmologically relevant effect, such a phenomenon has never been observed, as far as I know. And I also never even heard of something like that. On the contrary: all experiments have shown that the speed of light is a universal constant. Can you provide a link or a reference, where you encountered such a thought?

However, what has been theorised is the natural reduction of the frequency of photons (or the increase of wavelength) as an alternative to the redshift introduced by the expansion of the universe. But as I see it, there is no coherent theory that can explain such a phenomenon.

Originally Posted by Dishmaster

Originally Posted by FalconX2000

Thanks, but I am still unsure about the theorised decay of the speed of light. Would that mean that, barring other forces interfering, things would get brighter on Earth in the future?

If you are thinking of a cosmologically relevant effect, such a phenomenon has never been observed, as far as I know. And I also never even heard of something like that. On the contrary: all experiments have shown that the speed of light is a universal constant. Can you provide a link or a reference, where you encountered such a thought?

However, what has been theorised is the natural reduction of the frequency of photons (or the increase of wavelength) as an alternative to the redshift introduced by the expansion of the universe. But as I see it, there is no coherent theory that can explain such a phenomenon.

http://www.answersingenesis.org/docs...cdk_davies.asp

http://www.worldnetdaily.com/news/ar...TICLE_ID=39733

Both articles are based on something from 6 years ago which everyone in the scientific world has forgotten 6 years ago. The figures:


# In 1738: 303,320 +/- 310 km/second
# In 1861: 300,050 +/- 60 km/second
# In 1877: 299,921 +/- 13 km/second
# In 2004: 299,792 km/second (accepted constant)


The explanation is simple. It was not easy in the past to measure something moving at such unbelievable speeds. As time has passed, we have developed more accurate instruments which have narrowed the margin of error, so eventually arriving at the correct speed. How the speed of light was measured (about halfway down page):


http://en.wikipedia.org/wiki/Speed_of_light


With answersingenesis there are two rules to remember.

1) They can only show the bible right by showing science is wrong, and there is no lie or depth they will not stoop to, to do this.

2) Remember Rule One.

Originally Posted by Cyberia

Both articles are based on something from 6 years ago which everyone in the scientific world has forgotten 6 years ago. The figures:


# In 1738: 303,320 +/- 310 km/second
# In 1861: 300,050 +/- 60 km/second
# In 1877: 299,921 +/- 13 km/second
# In 2004: 299,792 km/second (accepted constant)


The explanation is simple. It was not easy in the past to measure something moving at such unbelievable speeds. As time has passed, we have developed more accurate instruments which have narrowed the margin of error, so eventually arriving at the correct speed. How the speed of light was measured (about halfway down page):


http://en.wikipedia.org/wiki/Speed_of_light


With answersingenesis there are two rules to remember.

1) They can only show the bible right by showing science is wrong, and there is no lie or depth they will not stoop to, to do this.

2) Remember Rule One.

Thanks, though I hadn't realised the first one was a religious site. I first read it in the papers a few years ago, something to do with measuring the speed of light through polar ice.

When you asked for sources, I just googled and found what I could.

Thanks.

It would be funny, however, if it turned out that the lowering constant was due to the expansion of space (In the sense that our measurement of distance was getting longer, but our measurement of time was staying the same).

IE. We see light as slower because our meter stick is getting longer?

I don't actually think that's happening. I'm just thiking it would be funny if it were.

The relevant area of physics here would be "VSL" (Variable Speed of Light). It is one of several constants that have, from time to time, been proposed in a number of theories to vary with time. As I understand it (which is not very well at all) this is done in an attempt to deal with some outstanding problems in cosmology. VSL also likely creates more problems than it solves.

Regarding the question... why would it get concentrated? I doubt you'd notice any difference. A phone-call to Pluto might take a microsecond longer?