Categories: Guide to Space

Why Can’t We See the Big Bang?

Since telescopes let us look back in time, shouldn’t we be able to see all the way back to the very beginning of time itself? To the moment of the Big Bang?

You’ve probably heard that looking out into space is like looking back in time. As it takes light 1 second to get from the Moon to us. Whenever we view it, we’re seeing it 1 second in the past. The Sun is 8 light minutes away, and the light we see from it is from 8 minutes into the past.

A better example might be Andromeda, it’s 2.5 million light years away… and you guessed it, we’re seeing it 2.5 million years in the past. Since the Big Bang happened 13.7 billion years ago, using this idea, shouldn’t we be able look all the way back to the beginning of time, even if we’ve misplaced the key to our Tardis?

At the very beginning of the Universe, seconds after the Big Bang, everything was mushed together. Energy and matter were the same thing. Dogs and cats lived together. There was no difference between light and radiation, it was all just one united force.

You couldn’t see it, because light didn’t actually exist. There were no such thing as photons.

However, if you’re still insisting there’s no such thing as photons, you might want to check yourself. After these things started to separate. Photons and particles became actual things. Electromagnetism and the weak nuclear force split off and formed new bands, but could never quite get the momentum of the original lineup.

By the end of the first second, neutrons and protons were around, and they were getting mashed by the intense heat and pressure into the first elements. But you still couldn’t see that because the whole Universe was like the inside of a star. Everything was opaque. It was Scarlett Johansson hot, and too crazy to form stable atoms with electrons as we see today.

Artist’s conception of Planck, a space observatory operated by the European Space Agency, and the cosmic microwave background. Credit: ESA and the Planck Collaboration – D. Ducros

After the Universe was about 380,000 years old, it had cooled down to the point that proper atoms could form. This is the moment when light could finally move, and travel distances across the Universe to you and get caught up in your light buckets. In fact, this light is known as the cosmic microwave background radiation.

So, how come we don’t see all this freed light in all directions with our eyes? It’s because the region of space where it exists is so far away, and travelling away from us so quickly. The light’s wavelengths have been stretched out to the point that light has been turned into microwaves. It’s only with sensitive radio telescopes and space missions that astronomers can even detect it.

Unfortunately, we’ll never be able to see the Big Bang. Even though we’re looking back in time, right to the edge of the observable Universe, it’s just beyond our reach. If you could look at the Universe at any point in time, what would it be? Tell us in the comments below.

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Fraser Cain

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay. Here's a link to my Mastodon account.

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