No, there was no "single point". This is a pop-science misconception that has no bearing on reality as far as we know. The "singularity" does not mean "point" it means "the place where our math model gives un-physical results and we don't know what was really going on."eugene pletcher said:Regarding expansion, from the present to the past: Do light beams (generally) converge to a single point, in the remote past, as geometry and matter was also condensed to a single point, prior to the big bang?
Thank you.
phinds said:No, there was no "single point". This is a pop-science misconception that has no bearing on reality as far as we know. The "singularity" does not mean "point" it means "the place where our math model gives un-physical results and we don't know what was really going on."
The beginning of the universe as we understand it was not a point and may in fact have been infinite in extent.
By the way, don't feel bad that you got sucked in by that mis-information. There are many dozens, probably hundreds, of posts here with people asking questions based on exactly that misunderstanding.
Yes, and if you go back far enough there were no galaxies.eugene pletcher said:Appreciated. Was the distance between galaxies not smaller in the past?
No, light is emitted from celestial objects, generally, radially and the angle between any two rays doesn't change as you get closer to the source.If so, does that not imply light beams were closer then they are now?
phinds said:Yes, and if you go back far enough there were no galaxies.No, light is emitted from celestial objects, generally, radially and the angle between any two rays doesn't change as you get closer to the source.
The photons that were emitted billions of years ago were closer to their source of origin than they are now, but so what? The photons that leave our sun are all within one solar diameter of each other when they leave and they get farther apart, but "converging" is the wrong way to think about that process in reverse.eugene pletcher said:Again thanks. Even when viewing several billion light years away, the light paths (travelling toward Earth) are not converging in the remote past?
I think in the sense that you mean (and I may be misinterpreting you) then of course they do because it's all just geometry. Mass has nothing to do with it.eugene pletcher said:May I ask just one more question? Does expansion separate individual photons, which are massless? I'm not referring to geodesics, or curved space. I'm interested to know if expansion itself can cause two, almost parallel, photons to separate. I suspect that the answer is no.
Thanks :)
Light beams travel through space as electromagnetic waves, which do not require a medium to propagate. This means that light can travel through the vacuum of space at a constant speed of 299,792,458 meters per second.
The farthest we can see back in time with light beams is to the cosmic microwave background (CMB), which is the oldest light in the universe. This light was emitted about 380,000 years after the Big Bang, making it about 13.8 billion years old.
No, we cannot see the actual Big Bang with light beams because the universe was too hot and dense for light to travel during that time. However, we can observe the afterglow of the Big Bang, called the cosmic microwave background, which provides evidence for the Big Bang theory.
The expansion of the universe causes light beams to stretch out over time, resulting in a phenomenon called cosmological redshift. This means that the wavelength of light increases as the universe expands, causing the light to appear more redshifted and making distant objects appear to be moving away from us.
Yes, light beams can be used to study the history of the universe. By analyzing the light from distant objects, scientists can learn about the composition, temperature, and expansion of the universe at different points in time. This allows us to piece together the story of the universe from the present all the way back to the time of the Big Bang.