Cosmic timeline 01
Let’s begin our cosmic timeline with a measurement of the smallest indivisible unit of meaningful time. This is the time it takes light, travelling at 186,000 miles per second, to travel across the smallest measurement of length which has any meaning.
This turns out to be 0.00000000000000000000000000000000001 of a centimetre, and is called a ‘Planck length’, named by quantum physicist Max Planck in the first years of the twentieth century. This tiny unit of time is called, yes, you have guessed it, ‘Planck time’. This turns out to be 0.00000000000000000000000000000000000000000001 of a second, or 10 to the power of minus 43. This is a tenth of a millionth of a millionth of a millionth of a millionth of a millionth of a millionth of a millionth of a second. What would we do without all these zeros?
But when and how does time begin?
The modern theory of how our Universe began is very mysterious.
About 15 billion years ago the Universe suddenly existed where earlier there had been absolutely nothing. This “nothing” really was nothing! This “nothing” was not an empty space it was the absolute absence of space and time.
So how did the Universe suddenly appear?
The best explanation for the answer to this puzzle comes from a part of science called quantum physics that tries to explain how and why atoms and radiation behave in the way scientists observe them behaving. Quantum theory works with a very strange discovery about subatomic matter called the uncertainty principle. This principle says that we can never know both the speed and position of a subatomic particle at the same time. This principle comes from observing this subatomic world, not from understanding how and why these behaviours happen.
Werner Heisenberg, a German physicist discovered this principle in 1927. He went on to make a link between the speed and position of subatomic matter. He suggested linking the mass of creation with the time of creation in the same way. In the quantum universe matter can pop in and out of existence, and empty space is full of particles coming in to existence and then non existing.
This helps explain how the Universe came from nothing. Inspired by quantum theory, Edward Tryon suggested back in the early 1970′s that if virtual particles can pop into existence according to the uncertainty principle, why not the beginning of our Universe?
The only problem in this theory was that by putting the whole Universe into something as minuscule as a quantum particle the gravitational field produced would be so strong that it should have crushed the Universe out of existence immediately.
So how did the Universe survive 15 billion years ago?
For the Universe to pop in to existence and not be crushed out of existence by its own gravitational field, it would have had to have expanded beyond the scale of its quantum beginnings before it collapsed in on itself. In the early 1980′s a theory called the theory of cosmological inflation explained how this expansion might have happened.
This theory says that just one hundred-million-billion-billion-billionth of a second after the Universe appeared it went through a massive expansion. This huge expansion spurt took the Universe beyond the scale of the quantum world, before slowing down into the state of expansion astronomers observe today.
This was the Big Bang!