Is the speed of light slowing down?

Wish I could soak this up. First instinct is, there is some truth, because in general nothing is ever static, is always changing. Too bad, tho' , checked out article and math is over my head. Without being versed in constants represented, and more math than I have can't really judge, so will leave to experts.

Again, I realize, I know enough to know what I don't know! :) Thanks Tessa.

thanx, Char!

The speed of light varies depending upon what medium it is passing through. Class is a slower medium than air. So is water. That's how our glasses (really plastic) refract the light to improve our vision.

The red shift is due to relative motion, not to the speed of light. If the red shift was due to the speed of light, the light that passed through glass or water would have a red shift.

maybe, maybe not
-- the red shift occurs in quanta, not smoothly, so that would indicate that the universe is expanding in fits and starts, not continuously, unless there is some other explanation for the red shift

Cool point Tessa! Can't participate, but will try to watch and learn.

Char, I appreciate your willingness to learn
-- never mind the math
-- when a fire truck goes by, you hear the sound of the siren changing in pitch
-- it gets higher as it approaches you, and lower as it goes away from you
-- light does the same thing, appearing more blue when it approaches you, and appearing more red when it goes away from you
-- this shift to the red or blue is measured on a spectrum, to determine how fast the light source is moving, and in which direction it is moving
-- the spectrum is that pretty picture that looks like a rainbow

Yes, that I do understand, about the spectrum. Just had not thought of it in this context. And I get Larry's point too, that the medium also effects the bending, or shift of the light. Is anyone even sure that all "space" is equal? What about other residual, fine mist of some sort left over from millions of years ago, between them and us? So....many variables, and perhaps I over simplify, or complicate. When you boil it down like above, I can easily see your position.

we don't know, but it is interesting to contemplate

Tessa,

The speed of light in a vaccum is a constant (so far as we know) so the red (or blue) shift is due to the relative velocity of the light source, not the light. (Any light you can see must be coming toward you. Light moving away from you cannot be seen (nor caught).

The universe is expanding at changing rates. It seems that it was slowing in its expansion for quite a long time but in the last few billion years it has been expanding faster and faster.

It's hard to say what "space" is just as it is difficult to define "time" or "energy."

If there is some "mist" or gas or dust between us and the light source, it shows up by blocking some wave lengths and not others. The size of the particle makes a difference in the colors it blocks or reflects.

maybe -- can you explain the quantum nature of the red shift?

Light is a quantum phenomenon so all aspects of light are quantum in nature. If you observe a large number of photons (light packets) the probabilities "smooth over" the quantum aspects. That's why we don't see the quantum fluctuations or otherwise feel them.

But the red shift of light is not measured as a single photon. Therefore, though at its most basic, the red shift must be quantum in nature, any measurement of it would not be. (Does that make sense?)

Maxwell's laws show that speed of light in a vacuum, c0 is related to the magnetic constant and the electric constant (vacuum permittivity), ε0, by the formula

Hold on guys, I'm still back here. Just kidding, leave me in the dust! :)

Thanks for the mist info, and good other thoughts Larry. Yes, seems to make sense to me, but want to hear Tessa's take.

I especially like the part about the light coming toward us, or else we could never catch it. :) Some say that's what we would have to do to return to the past (time travel).

What happened, did I ruin it? I am very interested in the concept that the universe may or should I say has changed the rate at which it is expanding. Is this accepted or disputed theory?

I'm thinking -- and besides, there is no point in debating with Larry because he has already made up his mind
-- so, Larry, how do YOU explain quasars?

Char,

I don't think you ruined anything. For me there is no particular question to answer (or ask). What would you like to know? I can share my own version of reality and give you an idea of how many more things we are ignorant about than we realized before. (The more we learn the more things we realize we don't know. )

I like the speed of light slowing down a whole lot better than dark matter and dark energy -- and what about quasars?

Quasars (quasi stellar sources) could be all sorts of things but most likely something involved in the collapse of super big stars or collisions of such things.

We do know that there seems to be a super massive black hole in the center or each of the visible galaxies. (When those first formed there must have been some really big super-novas.) But it's hard to see how the energy of gas falling into such a black hole could be a consistent source of the energy from a quasar.

In other words, though one gets some ideas, one really doesn't know what's going on there/then. The universe is different now in many respects.

(See? There are lots of things about which I have not made up my mind but I usually don't "lecture" about those things. :-)

Dark matter and energy are (apparantly) an entirely different phenomenon from quasars. But the evidence for at least dark matter seems pretty substantial.

I don't think light actually has a velocity in the sense that matter does. Since light has no time, velocity really is meaningless if you take a photon's point of view. So, since light lacks velocity, it could hardly go slower. It's our perception of its velocity that could change. (That last sentence is hard to explain but it has a lot to do with measuring techniques.)

when I studied astronomy at college in the 1970s, astronomers were already insisting that the red shift for quasars had to be an indicator of something other than distance
for example,
Gravity Field Red Shift Theory

Sorry, I have to appear arrogant again. :-)

His arguments are weak. There are plenty of deep gravity well objects close (in astronomical terms) to us and they don't show that red shift. There is also the "standard candle" novas whose brightness we know which show the appropriate red shift for their perceived brightness. In other words, the data don't support his conclusions.

The idea of the "Big Bang" still could be overturned and disproven but so far the "standard model" is the most complete explanation we have.

One more thing. He talks as if space already existed before the matter/energy of the Big Bang came into existence. That is not the case according to the standard model. The space did not exist before or independently of the matter and energy. Time and space and energy all started together. (There was no time before time. :-)

We have greatly increased our knowledge of the early universe since the 1970s. If the red shift was an indicator of something other than distance one would have thought that many other features of the universe would indicate that.

Tessa, I just read that article, and it says it is pretty much disproven, is that wrong?

Quasars seem to be, from the WIKI article, like the energy that swirls water at the edge of the sink as the water forms a whirlpool flowing out (or INTO the drain). As the black hole is born, while the energy is high, it seems to emit large amounts of energy as light and sound and what ones we see are the little piece of time when they were at that point. If the radio portion is predictable, it would probably repeat in cycles as it swirled.

Hey, if everybody is going for a theory, thought I would throw that out. :)

Those we see now, in actuallity, are now probably plain ole center black holes of galaxies, except we are so far away, we see that one little chapter happening. And that chapter probably took so long, we (in our short time frame) don't even realize it's just a very limited part of the whole process.

sorry, but this one is full of mathematical equations

http://newphysicstheory.com/Theory%20Part-I.htm

This definitely claims to prove the relationship of gravity to velocity of light. I just read through it quickly. Isn't the vacuum of space the reason it was discounted for the red shift?

The same with Einstein, as quoted below, is has to do with gravitation. NOW, i do realize there is other gravitational influence than just earth's. For example, added force due to magnetism, or even the way new planets are discovered because of variations in orbits of other bodies. So, perhaps there is something there. Far be it from me to dispute, it is interesting!

and then there's Einstein, himself:

Unfortunately, due to Einstein’s Special Relativity (where the velocity of light c is assumed to be constant) most scientists incorrectly assume c is always constant. In fact Einstein confirms that the constant velocity of Light is only true in non-accelerating systems (i.e. Special Relativity) - General Relativity (the real world of accelerating systems and thus Gravity) is founded on a changing velocity of Light in a Gravitational Field, which is in turn created by Matter. e.g. The curvature of the Light past the Sun. Thus he writes;

Special relativity is founded on the basis of the law of the constancy of the velocity of light. But the general theory of relativity cannot retain this law. On the contrary, we arrived at the result that according to this latter theory the velocity of light must always depend on the coordinates when a gravitational field is present. (Albert Einstein, 1954)

http://www.spaceandmotion.com/Physics-Reality-Forces-Light-Gravity.htm

That relates right back to the permittivity equation I originally looked at, so I'm getting warm..... :)

http://en.wikipedia.org/wiki/Quasars,_Redshifts_and_Controversies

This is the link to the critique I read. Is it not correct, what do you think?

good article
my point is that it is controversial, and not settled science

10-4!