ChatterBank0 min ago
Space
Following on from the question below about stars and the universe .
As stated , when we look at a star ( apart from our sun ) , what we are seeing is the star as it was way back in the past ; because it has taken the light years to reach us .
This is also the case with respect to the pictures that the Hubble telescope has sent us , showing those amazing pictures of the light from stars , just reaching us .
Am I therefore correct in the following -
At the moment of the big bang , the universe expanded at a rate far exceeding the speed of light , which is why stars that have come into existence are at a position in the universe which is so many light years away from the position of the earth in the universe ; which is why the light from these stars are only just reacing us .
Is that a correct explanation as to why for example , the hubble telescope is showing us pictures from these galaxies , which is only just reaching us ?
If the above is not correct then please explain in not too techinical terms .
As stated , when we look at a star ( apart from our sun ) , what we are seeing is the star as it was way back in the past ; because it has taken the light years to reach us .
This is also the case with respect to the pictures that the Hubble telescope has sent us , showing those amazing pictures of the light from stars , just reaching us .
Am I therefore correct in the following -
At the moment of the big bang , the universe expanded at a rate far exceeding the speed of light , which is why stars that have come into existence are at a position in the universe which is so many light years away from the position of the earth in the universe ; which is why the light from these stars are only just reacing us .
Is that a correct explanation as to why for example , the hubble telescope is showing us pictures from these galaxies , which is only just reaching us ?
If the above is not correct then please explain in not too techinical terms .
Answers
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//At the moment of the big bang , the universe expanded at a rate far exceeding the speed of light//
Probably this is "inflation" - some people don't like this idea but it has been very sucessful in explaining many observations and is so generally accepted.
//which is why stars that have come into existence are at a position in the universe which is so many light years away from the position of the earth in the universe ; which is why the light from these stars are only just reacing us.//
Not necessarilly due to the rapid "inflationary" period - the Universe is still expanding slower, carrying stars further away.
Do not fall into the trap of thinki the big bang was an explosion of mass and energy into an empty Universe.
Physical space itself was created at that time.
When we say the Universe is expanding we don't mean the debris from an explosion is just moving, but the actual fabric of space is expanding
Probably this is "inflation" - some people don't like this idea but it has been very sucessful in explaining many observations and is so generally accepted.
//which is why stars that have come into existence are at a position in the universe which is so many light years away from the position of the earth in the universe ; which is why the light from these stars are only just reacing us.//
Not necessarilly due to the rapid "inflationary" period - the Universe is still expanding slower, carrying stars further away.
Do not fall into the trap of thinki the big bang was an explosion of mass and energy into an empty Universe.
Physical space itself was created at that time.
When we say the Universe is expanding we don't mean the debris from an explosion is just moving, but the actual fabric of space is expanding
If you've not encounterred this idea before it might seem hard to accept.
How do we know?
Hubble showed that the further away an object was the faster it seemed to be flying away from us.
You wouldn't get that in an explosion - nearer material and further away material would move at roughly the same speed.
The Universe itself is expanding like dough rising
The further away a point is the more space is between us and the more space there is to expand and so the faster the object seems to be flying away from us.
How do we know?
Hubble showed that the further away an object was the faster it seemed to be flying away from us.
You wouldn't get that in an explosion - nearer material and further away material would move at roughly the same speed.
The Universe itself is expanding like dough rising
The further away a point is the more space is between us and the more space there is to expand and so the faster the object seems to be flying away from us.
To supplement jake's well reasoned explanation, the inflationary epoch[i (or period) happened very early on following the Big Bang... at less than 10^-35 seconds and only lasted for an extimated 10^-32 seconds, after which the expanding universe folowed today's known law of physics. During the [i]inflation] the scale from unimaginably small to the end results has been compared to a beginning of something far smaller than a photon to about the size of grapefruit... not terribly impressive to our minds but something that even astrophysicists have diffuclty grappling, except in the world of mathmatics...
Thanks for that - i'm not sure if your reply has answered the question i'm attempting to ask .
What I am trying to understand is what has been the process which has resulted in the earth being hundreds of light years from a particular star .
Is it that because the universe has been continually expanding from the moment of the big bang- so for example a particular star would have been formed at a location and time in the universe ;and the earth was formed at a different location and time ; accounting for the massive distances between the star and the earth and for the light to travel; in order to reach the earth's location in the universe , hence the light only just reaching us ?
What I am trying to understand is what has been the process which has resulted in the earth being hundreds of light years from a particular star .
Is it that because the universe has been continually expanding from the moment of the big bang- so for example a particular star would have been formed at a location and time in the universe ;and the earth was formed at a different location and time ; accounting for the massive distances between the star and the earth and for the light to travel; in order to reach the earth's location in the universe , hence the light only just reaching us ?
Aside from our local star, Sol, stars can form close together, they can even form binary (or larger) systems. It just so happens it didn't here. Which might just be part of why we came to be here rather than somewhere more complex.
Fact is that he stars have to be somewhere and if too many were near us life may not have had the conditions it needed to evolve something like humans.
Yes the universe has ben expanding ever since, although at a more sedate pace since the initial inflationary burst.
Unsure I follow your question. A galaxy tend to stay roughly together not splitting apart due to the expansion of space because of the gravitational attraction of the stars etc..
The thing is things form where they find themselves and we only have one local star which we orbit.
Hope that helps.
Fact is that he stars have to be somewhere and if too many were near us life may not have had the conditions it needed to evolve something like humans.
Yes the universe has ben expanding ever since, although at a more sedate pace since the initial inflationary burst.
Unsure I follow your question. A galaxy tend to stay roughly together not splitting apart due to the expansion of space because of the gravitational attraction of the stars etc..
The thing is things form where they find themselves and we only have one local star which we orbit.
Hope that helps.
Yes the "inflation period" is a device that is used to make a lot of other things work, think of it as a missing peice of knowledge that we put in a black box so we can move on.
I think you may be confusing stars with galaxies. All the stars you can see are within our own galaxy and they are constant neighbours. Stars are dying and being born all the time. We see all stars as they where when their light started, even our own sun we see 8 light minutes ago.
The light from distant galaxies is more a function of the equipment used to detect them. The light source produced the light and that light travels to our lenses. The Hubble deep field for example was made by pointing at the same bit of sky for days and collecting the light, then using image enhancing software to extrapolate the pictures. The light from those galaxies didn't just arrive its just that we where suddenly able to see it.
I think you may be confusing stars with galaxies. All the stars you can see are within our own galaxy and they are constant neighbours. Stars are dying and being born all the time. We see all stars as they where when their light started, even our own sun we see 8 light minutes ago.
The light from distant galaxies is more a function of the equipment used to detect them. The light source produced the light and that light travels to our lenses. The Hubble deep field for example was made by pointing at the same bit of sky for days and collecting the light, then using image enhancing software to extrapolate the pictures. The light from those galaxies didn't just arrive its just that we where suddenly able to see it.
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