Is light really a constant?

Originally posted by predator0187
It would break the laws of physics if light could go on indefinitely, as entropy is another key principle...

How would it violate entropy or any other law? I'm not seeing it.

I don't think you could 'hold' a beam or photon, I tend to think of it more as an elements half-life, and maybe there is a 6-7 billion year half life, making galaxies at this distance appear 'red shifted' and moving away from us. Rather than the universe expanding, maybe the light is 'fading', if you catch my drift...

There was nothing wrong with suggesting that hypothesis as it was suggested by scientists and seriously tested...and rejected, by evidence.

Tired Light

In general, any "tired light" mechanism must solve some basic problems, in that the observed redshift must:

admit the same measurement in any wavelength-band
not exhibit blurring
follow the detailed Hubble relation observed with supernova data (see accelerating universe)
explain associated time dilation of cosmologically distant events....

These conditions became almost impossible to meet and the overall success of general relativistic explanations for the redshift-distance relation is one of the core reasons that the Big Bang model of the universe remains the cosmology preferred by researchers.

However to suggest it now that it's been rejected by evidence is probably not warranted unless there is something new to add, like new evidence or a new way to overcome the stated problems with the idea.

reply to post by Arbitrageur


The idea that photons never stop and continue at the maximum velocity of the universe, indefinitely.

There are articles where galaxies are moving away from us at twice the speed of light, that would mean it is moving at the speed of light away from us, and we are moving at the speed of light away from it. That would mean our mass is infinite, no?

I could be misunderstanding this though...

Pred...

Star because any intelligent discussion deserves one.

reply to post by predator0187

No it doesn't violate any laws I know of for a photon to travel indefinitely...apparently that's what they do, until they encounter something, as far as I can tell.

Also there are a lot of misconceptions about galaxies traveling away from us faster than the speed of light, which are addressed in this paper:

Common misconceptions of cosmological horizons

We use standard general relativity to illustrate and clarify several common misconceptions about the expansion of the Universe. To show the abundance of these misconceptions we cite numerous misleading, or easily misinterpreted, statements in the literature. In the context of the new standard Lambda-CDM cosmology we point out confusions regarding the particle horizon, the event horizon, the ``observable universe'' and the Hubble sphere (distance at which recession velocity = c). We show that we can observe galaxies that have, and always have had, recession velocities greater than the speed of light. We explain why this does not violate special relativity and we link these concepts to observational tests.

I actually need to study this paper myself as I've only skimmed through it.

The "Hubble sphere (distance at which recession velocity = c)" they mention is so distant, I didn't think we could see much past it anyway, and there are corrections that need to be made to the Hubble constant at that distance because it's no longer constant anymore due to the expansion of the universe, so it gets rather complicated. But if it's true that another result of relativity is that "we can observe galaxies that have, and always have had, recession velocities greater than the speed of light.", then we have another example of how relativity is not intuitive.

And none of this involves infinite mass.

reply to post by Arbitrageur


"So the lattice does not absorb this photon and it is re-emitted but with a very slight delay."

What is happening to the photon during this delay? It can't just hang in there. My explanation might be technically wrong, but generally speaking it's correct. An atom receives a photon (I call it absorb, because the original photon ceases to exist and the photon's energy is passed on to the atom), then after a slight delay it re-emits it.