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Asked by to Thomas, Clara, Becky on 12 Mar 2014. This question was also asked by , .
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Thomas Elias Cocolios answered on 12 Mar 2014:
We wish we knew! Considering the current understanding we have of cosmology, we can only ‘see’ back in time towards the big bang, but not before. As such, I fear that we won’t be able to experiment on that question.
As I am very much an experimentalist (like Saint Thomas!), I prefer to refrain from speculating and therefore cannot answer your question any further. I am sorry for that =(.
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Clara Nellist answered on 12 Mar 2014:
Hi @nell. Great question! Unfortunately, we just don’t know. This is as far back as our understanding of the Universe goes. What we do have is a good idea about what happened just after the big bang up until now.
We know that moments after the big bang, the universe was very small, very hot and very energetic. There were lots of new particles whizzing around and making light. But because it was so packed together, the light kept bumping into other stuff and couldn’t go anywhere. After a while (actually when the Universe was about 380,000 years old) everything cooled down and spread out enough that the light could escaped and the particles made Hydrogen atoms. The Hydrogen started collecting together to make Helium. Eventually this turned into stars where heavier elements were made because of nuclear fusion (lighter elements make heavier ones and release energy). Fun fact – every thing heavier than the element Iron comes from stars exploding at the end of their lives!
Something else very interesting is that we have antimatter in the Universe. These are particles that are exactly the same as the ones we know (electrons, protons…etc) in every way except that they have an opposite charge. So for example, the antiparticle of the electron is called the positron. It weighs the same, but it has a positive charge instead of a negative charge. If you bring a particle and it’s antiparticle together they annihilate!! Both of them disappear and there’s only energy left. So, if after the big bang, matter and antimatter were created in the same amount, over time they should have all met up and distroyed each other. But they didn’t, because everything we see is made up of matter and almost all of the antimatter has gone (unless we make a little bit more, which we can do). So that means that they *are* different in some way, that we just don’t understand yet. So, if you became a scientist in the future, maybe this is a problem you could solve :).
Back to the big bang… because the universe expanded from the big bang, there are different ways our universe can go. Either it will expand forever with everything getting further and further apart. Or, it might begin to slow down and come the other way, collapsing in on itself. If this happens, everything in the universe would all rush back to the same point in what’s called the Big Crunch. Which *could* have been what happened before our universe started, but this is just one suggestion and we don’t know for sure.
Comments
tochi62 commented on :
good question and nice awnser clara
thomas not so much
Thomas commented on :
See, I disagree with you (and partially with Clara). In her answer, she says that ‘we know’ and that ‘these things happen’. While we have indication that support the big bang theory, claiming absolutely that it happened seems wrong to me and it is something that I do not accept. No one, today, can claim to re-start that process and observe it happen.
I can also not come up with a better theory, so I do not fight against it either. I think it is however always important to draw a clear line between the worlds of experimental work and observation, and that of fundamental speculation. This is one of the reasons why I never wanted to do cosmology or particle physics and that I am happy to work on nuclear physics where you can test your models and theories and reproduce your findings.
However, if you are passionate about cosmology and the big bang, I invite you to explore it fully. It will be a journey that you would never have guessed could be and I am sure you will enjoy it to its fullest!
Clara commented on :
Thomas is right that when I say we ‘know’, what I mean is, that we have some evidence for and a lot of scientists agree. In science you can never actually know anything is true for certain, as things can only be proved to be wrong, not right. There are some things that we used to ‘know’, that we now know are wrong. You know what I mean? 😉 And that’s science!
But I wouldn’t agree that it’s all speculation. We can recreate parts of what we think the Universe was like pretty early on. For example, there is an experiment at CERN called ALICE and they have been studying something called the quark-gluon plasma. This is a soup of particles in a hot and tightly packed state. While we don’t know for sure that this is what the Universe was like, it’s a good suggestion and we learn a lot from studying the particles in this state.