The light that was generated after the Big Bang has been travelling for billions of years but what happens say after a trillion or two years hence will that same light continue to travel without slowing or diffusing into nothingness? Does dark matter have a slowing effect on light?
So far as we can tell, light will travel literally forever, if it doesn’t run into something first. The photons will get further and further apart, and each individual photon will lose energy to the cosmological redshift, but they’ll never cease to exist or slow down.
There is no light created by the big bang. In fact it was silent (no air molecules to carry the sound.) We can not view the light as if there is any light it is outside the Universe. We can view the heat residue though but that is about it. Light will travel forever and ever. The intensity of th light though diminishes the minute it leaves the sourece. that is why the stars aren’t as bright as the sun. Eventually the wavelength will be too low to visualise but the light will still be there.
Can I point out that lighgt’s wavelength is not directly dependent on it’s intensity i.e. whatever measure of intensity you use decreasing the intensity does not necessarily mean decreasing the wavelength.
True I agree but the itensuty of the light will make it visible for a greater distance than a less intense llight.
However that’s irrelevant to the CMB as you’re talking about how intensity drops off from a point source, where’s the source of the CMB simply cannot be regarded as a point source.
The only effect that is really relevant here is cosmological redshift.
i disagree.
The wavelength typ and how intense that is. If i shine a light bulb up on the moon would you see it? No but a supernova in another glaxy can be see becuase it is brighter. the cosmological redhift is nearly irrelevent. The redshift is evidence that the universe is expanding.
Yes, but light from a bulb can be approximated to a poitn source, even the total light in a galaxy can be approximated to a point source to a faraway observer.
However the big bang cannot be approximated as a point source, though of course the big bang is not the source of the CMB as the early universe was opaque. However the source of the CMB occurred ~300,000 years cosmological time after the big bang and I think it’s fair to assume that the OP meant the CMB when they talked about light from the big bang they actually meant the CMB. The CMB cannot be approximated as a point source either, if the unievrse was not expanding or contracting the intensity of the CMB over any given solid angle would be pretty much constant (this is as, assuming a flat universe, that thoguh the surface of last scattering is getting further away it is also getting larger). Instead the universe is expanding and therefore cosmological redshift comes into play.
The big bang is when everything in the entire universe started to expand.
The point source for the big bang is everywhere. the bg bang is when the entire universe started to expand rapidly. There was no bang.
Entropy, heat death and Sarah Palin.
Seriously though dopers.
Proffesor Brian Cox, U.K. Particle Physicist, made a programme called ‘Wonders of the Solar System’ in which all energy, organized structure and information becomes a null space. Nothing to reference by, no means or material to generate new energy. I think of it rather like Montana!
Peter
A point source is unidirectional to observer, but a source that was everywhere sometime ago will be omnidirectional.
The source of the CMB (the surface of last scattering) is an expanding sphere (note that the sphere doesn’t expand due to the expansion of the universe, rather it expands at a greater rate due to the expansion of the universe) with the observer (of the CMB) at it’s centre.
He also played the keyboards in D:Ream.
The universe the very fabric of the univers everything in it is expanding. Where would you say the CMB is then
Everywhere. Which is what he is saying.