The big bang-how it all began

Let's match the time after the big bang with what happened to create a timeline of the start of the unverse. The big bang No space and no time, only energy concentrated into a single point. One million trillion trillion trillionths of a second later Time and space has begun. Space was expanding quicly and the temperature was about 100 million trillion trillion degrees Celsius. One ten billion trillion trillionths of a second after the big bang The universe was about the size of a pea. Matter in the form of tiny particles such as electrons and positrons had formed. Particles collided with each other releasing huge amounts of light. One ten thousandth of second after the big bang Protons and neutrons had formed as a result of collision between smaller particles . The universe was very bright because light was trapped as it was continually being reflected by particles. One hundredth of a second after the big bang The universe is still expanding and cooling rapidly. It had grown to the same size as our solar system, but there was still no such thing as an atom. One second after the big bang The universe was probably more than a trillion trillion kilometres across. It had cooled to about ten billion degrees Celsius Five minutes after the big bang The nuclei of hydrogen, helium and lithium had formed. Three hundred thousand years after the big bang The universe was about one thousandth of its current size. The temperature was about 3000 degrees Celsius. Electrons had slowed down to allow the formation of the first atoms. There was enough empty space in the universe to let light escape to the outer edges. The universe was dark. Two hundred million years after the big bang The first stars appeared as gravity pulled atoms of hydrogen, helium and lithium together. Nuclear reactions took place inside the atoms, causing nuclei of the atoms to fuse together to form heavier atoms. Planets began to form from swirling clouds of matter cooling and forming clumps. One billion years after the big bang The universe was beginning to become lumpy. The force of gravity pulled matter towards the lumpier regions, causing the first galaxies to form. What is the science of cosmology? How old is the universe believed to be? How did galaxies begin to form? How did we first work out that the universe was expanding? Galaxies were seen to be moving further and further apart Galaxies were seen to be spinning in an unexpected way Particle physics experiments showed that atoms were getting larger as the universe got older How do particle accelerators allow us to effectively look back in time? If you accelerate particles to a great enough speed, they travel backwards in time The high energy collisions of particles recreate the hot, dense conditions we think existed at the beginning of the universe Particle accelerators make wormholes that we can travel through to make measurements of the early universe Which of these particles is the smallest? atom neutron proton quark How long after the Big Bang was it before protons and neutrons could form from quarks? microseconds a few seconds hundreds of seconds How do we know that all of the fundamental forces of nature will simplify into one force at a very high energy? All of the experimental evidence we have obtained so far suggests that some of the different forces we know about are actually the same force if you go to high enough energies, and we expect this trend to continue The physics of the universe must be described by a simple, elegant mathematical equation – and one force is simpler than four forces We don’t know this at all – if we want to test this hypothesis, we’ll have to build bigger particle accelerators to further our understanding of the universe