Michio Kaku (加來 道雄, Kaku Michio) (b. January 24, 1947) is a Japanese American theoretical physicists specializing in string field theory, and a futurist.
In regards to the Big Bang Theory...if the Universe began with a single subatomic particle, where then did that subatomic particle come from?
There are several proposals for what happened before the Big Bang. One possibility is that the universe began as the collision of two universes.
Another possibility is that our universe sprouted or budded from a parent universe. This is the picture favored by some of the people who originally proposed the inflation picture. In this theory, our universe is immensely huge, but there is a probability that, at various points, another universe may suddenly start to emerge. Like a baby soap bubble sprouting from a larger soap bubble, this tiny universe would expand in another dimension and eventually separate from the parent universe. In this picture, the universe is extremely large, but constantly sprouts baby universes at different points in space and time, until each of these baby universes becomes a large universe in itself. Then the process continues again.
This is called "chaotic inflation."
And there is the possibility you also mentioned, that the universe started off as a tiny sub-atomic particle. But where did this particle come from? One possibility is that it came from Nothing. This may sound ridiculous, but it actually has some serious implications. If the universe started out as a bubble or particle which popped into existence out of nothing, it means that the universe is a quantum fluctuation of the vacuum. We know experimentally that the vacuum found in a laboratory is not empty, but is actually full of virtual particles, electrons and anti-electrons which are constantly popping into existence and popping back into the vacuum.
So quantum fluctuations of the vacuum are well established experimentally.
In this picture, the vacuum or Nothing is also full of baby universes which pop into existence, and then pop right back into the vacuum.
Usually, nothing more happens. These universes have their own Big Bang and then have a Big Crunch almost immediately afterwards. However, there is a finite probability that one such bubble popped into existence and then kept on expanding, without having a Big Crunch.
Perhaps our universe is one such bubble that kept on expanding.
The energy which determines if our bubble/universe keeps on expanding or jumps back into the vacuum is called the cosmological constant, i.e. the energy contained in the vacuum. The cosmological constant of our universe is quite small, and hence our universe keeps on expanding. However, even for modest cosmological constants, the universe would collapse back into a Big Crunch and then vanish back into the vacuum.
In other words, perhaps our universe is the winner of a cosmic lottery.
Perhaps the cosmological constant is usually random and large, and these universes pop into the vacuum, never to be seen. However, by chance, one such universe had a very small cosmological constant, and kept on expanding. And this is our universe. There are also some other reasons for believing that our universe started from Nothing. For example, our universe has an equal number of positive and negative charges. But electrical forces are so powerful that even if there were the tiniest imbalance between positive and negative charges, it would rip the universe apart. So why does the universe have a delicate balance between these two charges? Perhaps because the universe came from Nothing. Nothing has zero charge, and hence that may explain why our universe also has zero charge.
Also, our universe does not rotate. Galaxies can rotate, but their average rotation cancels out to zero in our universe. Perhaps this is because the original Nothing out of which we came does not spin.
Some might object, because matter seems to be coming from nowhere. But this might be an illusion. If you calculate the total matter in the universe, it is a very large number. But gravitational energy is negative. If you add up all the positive and negative energy of the universe, you get a number extremely close to zero.
If our universe had exactly zero energy, it means that it would cost nothing to create a baby universe from the vacuum. Universes are for free.This is the ultimate free lunch.
Some might also object because none of these scenarios are testable. But there is hope. Around 2015, the US will launch the first of a series of gravity wave detectors like lISA, designed to detect fain gravity vibrations in space, from colliding black holes to the Big Bang itself. The shock waves from the Big Bang were so intense that we expect gravity vibrations from the Big Bang to be circulating even today around the universe.
The various scenarios mentioned predict what the radiation from the Big Bang will look like.
Therefore, by simply examining the gravity waves emitted after the instant of the Big Bang, we can compare this post-Big Bang radiation to the predictions made by various pre-Big Bang theories, and hence weed out the incorrect theories.
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Michio Kaku Website
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