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This is the picture of the beginning of the universe. Seems unbelievable?
You might be wondering how we can have a picture of something that happened approximately. 13.8 billion years ago? Did someone Travel through time to take this? Well, the simple answer is, yes.
Physics can explain this phenomenon accurately.
Light moves at a speed. So, it means that the farther away something is from you, the longer it must take for its light to reach you. Simple right?
If you think about it, you are never really seeing ANYTHING as it is right now, but as it was in the PAST.
This is because light takes time to get to places. Light is definitely tremendously fast, so fast that it could circle the Earth 7 times in one second! So technically for all intents and purposes, everything close by is as it is.
Light's travel time becomes increasingly significant the further and further out you look.
So, for instance, it takes light about 1 second to get from the moon to the earth. This means that when we look at the moon, we are actually seeing it as it was one second ago. The sun's light takes about 8 minutes to reach us, so we see the sun as it was 8 minutes ago. We see the nearest star to the sun (proxima centauri) as it was 4 light years ago. the nearest major galaxy to ours, the Andromeda Galaxy was seen 2.5 million light years ago.
With modern telescopes and technology, we have now observed a gigantic number of galaxies which are so distant that we see them as they were BILLIONS of years ago.
Something special happens when we are observing especially distant objects. We notice that the further out we look, the simpler everything becomes.
There is a clear trend, that progressive distant galaxies are not as massive and less developed compared to those that are closer by. By surprise, that is exactly what you would expect because by looking out that far, we are looking at the earlier moments in COSMIC HISTORY, when the universe and all of its contents we less evolved.
Time machines exist. They are called telescopes. When we use them, we become time travellers, watching the history of the universe unfold right before our eyes.
We can look so far out into space and back in time that we eventually reached a point where stars and galaxies did not even exist yet. We can look at a time when the universe was so young and lacked any kind of structure at all. To everyone's surprise, we have a picture of that time.
You guessed it, its the one which was at the start of this blog! that is the universe as it was about 400 thousand years ago before it began any formation of celestial objects. Specifically,it is a photo of the 'Surface of Last Scattering'. This is the farthest thing that we can ever possibly see.
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