Lilly from New York City sent me this question a few weeks back. (I am sorry, I have been quite busy, and have not been able to get to your questions everyone, I will, promise!) She wanted to know what was there before the big bang which started our universe. Well the answer is probably going to not make you very happy Lilly, but it is the consensus among scientists that there was no "before the big bang". You see, the big bang was not just the start of space, it was the start of the universe. One of the properties of the universe is that time goes forward. So, the big bang was the start of time. If it is the start of time, there could not be anything before time started.
Lilly also wanted to know how planets stay in the sky. Well that is a great question, and I remember my daughter asking a question like that when she was about your age. All objects attract each other, so we (the earth) are attracted to the sun, and the sun is attracted to us. This mutual attraction keeps us spinning around the sun, and it works the same way for all of the planets.
I then used the idea of spacetime to explain gravity a bit further. It turns out space and time are the same thing , and this spacetime can be thought of as a big blanket.
Enjoy episode 23, and thanks Lilly!
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