Consider that Edwin Hubble who observed and measured that every galaxy was effectively moving away from each other and that the farther the object the faster the movement. He deduced from these observations and calculated the universe must be expanding. Then he extrapolated backwards and theorized the universe must have experienced a Big-Bang about 15billion years ago. So the universe is about 15 billion years old. (Creationists, please refrain from commenting.)
Consider that Albert Einstein theorized the speed of light is constant and space-time was dependant upon the other. (It's been proven experimentally.)
That 10-day old exposure photogragh was estimated/calculated those galaxies are as they appeared 13billion years ago. In other words, when the universe was only 2 billion years old. Remember, when we look at the Sun, its appearance is what it was 8 minutes ago.
So 13 billion years ago, the universe was much smaller than it is today. Thirteen billion years ago, the point in space we are located today would be much closer to those galaxies in that photo.
So the question is, why did it take light from these galaxies 13 billion years to reach us when they were only 2 billion years away?
2007-08-12 05:27:39 · 14 answers · asked by daffyd 1 in Science & Mathematics ➔ Astronomy & Space
This is due to the fact that space has not remained constant over time. Scientists have found that the Universe's space itself forms part of the expansion of the Universe, and that the expansion of space can take place 'faster' than the speed of light (although 'speed' is a rather inaccurate term to use here as it normally refers to motion THROUGH space rather than motion OF space). It appears that although the Universe is only some 14 billion years old, it is about 156 billion light years in diameter due to the expansion of space. As a result, the light traveling to us from distant galaxies is both farther from its originating galaxy AND farther from US than it should be if we assume that space is constant.
2007-08-12 05:35:50 · answer #1 · answered by Anonymous · 2⤊ 0⤋
It goes something like this (numbers in no way realistic):
Say that 13 billion years ago, we were only 2 billion LY apart. Which would mean that light would take 2 billion years to get here. But in the intervening time, an additional 11 billion LY of Hubble expansion has been added to the distance the light had to travel. Which means it took a total of 13 billion years to get here.
And that the galaxy in question is now MUCH MORE than 13 billion LY away.
2007-08-12 08:13:36 · answer #2 · answered by skeptik 7 · 0⤊ 0⤋
I remember reading somewhere that light isn't constant, but slows down slightly the further from the source it is... but anyway...
light moves a aproximately a constant speed, and we know how fast it is thanks to a kickass genius guy with these spinning cog thingys... anywho...
light takes a certain amount of time to move threw a certain amount of space, so the further the light has to travel the earlier it must have started it's journey... (ergo if you wanted to get home from work/school/whatever now you have to have left work at aproximately whenever [depending on the distance] for you to be here)...
the light is here now and has been traveling at a near as damnit to constant speed, for 13billion years...
also we're moving away from it too, so if 15billion years ago it was part of us, and 2billion years ago it was an comet's hurl away, we've been moving away from it for 13billion years, and the light we see has been traveling in a straight line... the light took 13billion years to get to the point in space where the earth is now, but when it left (if it could think) it would obviously not have known it would come in contact with any object.
2007-08-12 05:55:01 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Based on your info it would be true that it would only take 2 billion years for the galaxies light to reach us. However as as the universe expands, those galaxies got push to where they are now. So now after they have been moved to 13 billion lightyears away an it now takes that long for light to make it to us. Since the galaxies are no longer that close, it would be impossible for light to travel light speed and make it only take 2 billion years.
2007-08-12 05:42:00 · answer #4 · answered by ozzy4president51 or sean 3 · 1⤊ 0⤋
I was getting a headache there. The galaxies got further away so originally they were 2Byears away and now they are 13Byears away so light has to go further. I don't see a problem other than of your own making.
2007-08-12 05:37:55 · answer #5 · answered by Del Piero 10 7 · 0⤊ 1⤋
exactly... so its like looking at the rocks in the grand canyon... the farther u look out into the universe, the younger the universe looks... cuz it takes farther 4 the light to reach ur eyes
hope it helps
2007-08-12 05:35:02 · answer #6 · answered by Bob K. 2 · 0⤊ 2⤋
The speed of light can only be so fast
2007-08-12 05:34:19 · answer #7 · answered by jake 1 · 0⤊ 1⤋
If you know the rate of expansion you should be able to work it out for yourself
2007-08-12 05:35:01 · answer #8 · answered by Anonymous · 1⤊ 0⤋
Just enormous distances.
2007-08-12 05:57:04 · answer #9 · answered by Anonymous · 0⤊ 0⤋
An excellent question. I am eagerly looking forward to read the other answers. I wish I asked this.
green-meklar's answer seems to be logical. Thanks to you.
2007-08-12 05:36:01 · answer #10 · answered by Swamy 7 · 0⤊ 1⤋