question about time and space

[paulsamuel]

Hi,

I had a question about the relationship between time and space. As we look in space we see light from stars that originated thousands or hundreds of thousands of years ago. As we look at more distant stars we see light that originated millions or billions of years ago. It is therefore theoretically possible that if we looked far enough into the distance we would see light that originated at the time of the "Big Bang" (or at least shortly thereafter). The paradox is that at the moment of the Big Bang, everything was pretty close together, and wouldn't be distant. Any help in my confusion would be appreciated.

Thanks, Paul

 

[ImaHamster2]

Paul, this hamster will take a stab at your question before the real astronomers can give you a correct answer. <G>

Radiation dominated the universe for a few hundred thousand years after the Big Bang. As the universe expanded the wavelength of that early radiation decreased. Eventually that early Big Bang radiation became what is now seen as the cosmic microwave background radiation. That radiation last interacted with matter around four hundred thousands years after the Big Bang and pre-dates any light emitted by a stellar object. That radiation is nearly uniform across all the visible sky indicating a nearly uniform energy distribution in the early universe.

Don’t think there is any confusion on your part. The universe expanded more rapidly than the speed of light. Thus stellar light from the “opposite” side of the universe still hasn’t reached the Earth.

Hmmm…interesting to imagine that light from first stars as an ever-expanding sphere centered on the Earth. If the universe is still expanding faster than the speed of light there should be a limit distance at which a point in space is retreating from the Earth at the speed of light. Nothing past that “distance” would ever be visible from Earth. (Unless the expansion slowed.) Those early stars would seem to get dimmer and dimmer as the distance observed approached that limit.

 

[thed]

Wasn't there a recent press release claiming some group had imaged a galaxy at z=6. Thought to be about the time of 'first light' in the Universe. The earliest period of stellar formation.

Also, it is now thought very high energy gamma rays are from supernova when the earliest stars collapse as hypernova to form gamma ray bursters.

So in a way, we are seeing this earliest period of evolution.