Let me explain. A while back some scientists happened to notice that light from distant objects in space (stars and galaxies) was red-shifted. Upon closer observation they learned that the more distant the object the bigger the red shift. And this was the case no matter which direction you looked. Interesting...
Redshift of light is nothing new. Einstein developed theories that said redshift occurs in the light sourced from an object when that object is moving away from you. Information on redshift.. Other people have gone on to measure light from objects that are moving away from us at known speeds and have proven Einstein correct in this - light sourced from objects moving away is indeed red shifted, and the red shift increases as the departing velocity increases.
But note, Einstein never said that there could not be another phenomena that might also cause redshift.
When the scientists found redshift associated with distant space objects they jumped to the conclusion that the objects were moving away from us - and from only this one piece of evidence they went on to conclude the universe is expanding. But then, there was an issue with this idea. In a uniformly expanding universe the relative velocity between two objects grows in proportion to the distance between the objects. Based on the "observed expansion rate" of our universe, if two objects are > 4.5 gigaparsecs apart then the relative velocity between the objects will exceed the speed of light. Since it is well established that the speed of light cannot be exceeded, you either have to question the expanding universe hypothesis, or you have to invent some new concept that says you're really not exceeding the speed of light, something else is going on.
The concept invented was that the objects are not really moving apart from each other, rather the space between them is just expanding. Whaaaat?!! And then, on top of this, the theorists added the qualifier that the expansion of space is happening only on cosmic scales - this would explain why we don't see any "expansion of space" when we do precise measurements on things like the distance between the moon and the earth. Other theories have been formulated, and more are being formulated as we speak, to explain more of this picture of an expanding universe and to try to reconcile it with known and proven physics.
In my opinion the astrophysics community is long overdue take a big step back and re-consider the original, very possibly mistaken, notion that the redshift of light from distant objects is proof that the universe is expanding.
What else might cause the redshift seen when looking at distant objects? When it propagates through a media such as glass, light can undergo redshift - for example from Brillouin Scattering. When light propagates across millions of light years distance of space it is not travelling though 100% emptiness. Space could be considered a very low density media. So perhaps there is a yet to be discovered phenomena that is redshifting light as it propagates through this very low density media. Or perhaps it's a phenomena we have already seen elsewhere, but have yet to connect with what we see in space.
How would a person go about proving that light becomes red shifted as it propagates through space? Maybe you can catch a reflection of our sun's light off of Neptune (5600 million miles light propagation distance) and look for a redshift in that versus light directly from our sun (92 million miles light propagation distance). Or better yet, beam a laser at neptune and measure the light that is reflected back. If it is red shifted (after accounting for Neptune's relative motion due to its and Earth's measured and know orbits), then that would prove there's another phenomena behind the redshift.
Isn't this the "ether" concept?
ReplyDeleteThere is wide agreement in the astrophysics community that ”empty space” actually has lots of bits of matter floating and zipping around in it. Light-matter interaction in space is one possibility I suggest to explain the redshift of distant sourced light. This is not the traditional ether concept, but it might be considered an "ether type” concept. Against this as an explanation for the redshift, it's been argued that the amount of scattering of distant sourced light is insufficient to be consistent with the observed amount of redshift, if you assume it is from light-matter interactions.
ReplyDeleteI also suggest there are other possibilities - maybe the light-matter interactions over galactic distances are a different phenomena than any matter-light interactions we've characterized to date. Or maybe it’s not a light-matter interaction giving the redshift, but instead its a light-x interaction, where x is fleeting particles popping into/out-of existence, or the unknown-stuff-we-refer-to-as-dark-matter, or other. My point is that we don't know what causes the galactic distance redshift, and it's folly to conclude at this time, with our limited knowledge in this area, that it can only mean that distant things in all directions are becoming more distant as time passes.
Keith