The Big Bang




My Astronomy Website

The Big Bang

Written by keith grice
Saturday, 31 July 2010 20:49

14 billion years ago the universe didn’t exist, until the Big Bang…The Big Bang is the origin of space and the origin of time itself. We take a journey through space and time from the beginning to our place in the universe.

Our world is made up of cities, forests , oceans and people. Everything in the universe is made up from matter created in the first seconds of the Big Bang….Every star every planet every atom every blade of grass every drop of water. Water is ancient, the hydrogen atoms in water were born moments after the Big Bang, then came everything else…The Big Bang is the defining event of our universe and everything in it. The secrets of our past, our present, and our future are locked inside this one moment in time…To unlock the secrets of the big bang we have to travel outside our own solar system and journey even beyond our own galaxy….As we travel into deep space we are actually seeing into the past, and getting closer to be able to witness the dawn of time itself…..Passing the first infant galaxies and the first stars. We arrive back at the moment the universe began and face the biggest questions in all of science……This is the holy grail of physics, we want to know why it banged, we want to know what banged, we want to know what was there before the bang…..To get the answers we’ve built machines the size of cities to simulate conditions when the universe was created, as well as space telescopes to peer deep into our past…..Stephen Hawking said “ we are getting close to answering the old age questions, why are we here, and where did we come from, does the universe in fact have a beginning or an end, and if so what are they like. If we find the answer to that it would be the ultimate triumph of human reason, we would know the mind of God “…….The origin of the Big Bang is the greatest mystery of all time, and the more we learn the deeper the mystery becomes….We like to think that our universe is unique, however now we’re not so sure, perhaps there is a multiverse of universes…Another possibility is that our Big Bang is one of a number of Big Bangs…..But there is only one universe that we are sure of, and understanding this one is hard enough.

Since the late 1920s everything we know about how our universe works has been turned upside down….In 1929 at the Mount Wilson Observatory astronomer Edwin Hubble discovered that galaxies are not static in one place. Not only are they moving , but they are flying away from Earth at incredible speeds, and this was the first real evidence of the Big Bang…It became known as Hubble’s Law. What Hubble convincingly demonstrated by seeing the motions of those galaxies is that the universe is expanding…Theoretically an expanding universe must have started from a single point. So by measuring how fast the universe is expanding, astronomers calculated backwards and worked out when it burst into life. People ask me the question, how do you know the universe is 13.7 billion years old, I mean, smarty pants, you weren’t there 13.7 billion years ago, well when you watch T.V. on video tape you hit the stop button when you see an explosion, and you can run it backwards and see when it actually took place. The same thing takes place with cosmology, we can run the video tape backwards and then calculate when it all came from a cosmic explosion. You don’t have to be an astronomer to look back in time. If you look up at the night sky you’ll see stars that are millions of light years away, meaning it took the light from those stars millions of years to get here. So if you look back far enough you should be able to see the beginning of the universe…Named after the ground breaking astronomer, the Hubble Space Telescope allows us to look deep into the universe, back in time and closer to the moment of the big bang. But for scientist, winding back the clock to the Big Bang was just the first step…When people first here about the Big Bang theory they say, where did it take place, over here , over there, where did it take place. Actually it took place everywhere, because the universe was extremely small at that time. These are some of the most abstract and difficult concepts there are, and this is another, what came before the Big Bang ?..The fundamental laws of physics say that something can be created from nothing and it means that our whole universe, everything that we see, everything that matters to us could have arisen from precisely nothing….Its one of the biggest obstacles to understanding the Big Bang. First you have to believe that something was created out of nothing. Its impossible to describe the moment of creation in human language, all we know is from what may have been nothing, we go to a state of almost infinite density and infinite temperature and infinite violence…Understanding how nothing turned into something maybe the greatest mystery of our universe, but if you understand that, you start to understand the Big Bang. When time and space began, and when a great big explosion created everything. At the dawn of time the universe explodes into existence from absolutely nothing into everything….But everything is actually a single point, infinitely small, unimaginably hot, a super dense speck of energy. The Big Bang was so immense that it brought into existence all of the mass and all of the energy contained in all of the 400 billion galaxies we see in our universe from a region smaller than the size of a single atom….

The entire observable universe was a millionth of a billionth of a centimetre across at that time. Everything was compressed into an incredibly hot dense region. Its not even matter yet, just a point of raging energy, it was the beginning of the universe and everything in it. In that instant of creation all the laws of physics, the very forces that engineer our universe began to take shape. The first force to immerge was gravity. The fate of the universe, its size, structure and everything in it was decided in that moment. Gravity has shaped our universe. If gravity was weaker than it is we would have a very boring universe because everything would be flying apart so fast that no galaxies would be forming. If gravity was stronger than it is we would have a failed universe where everything would end up in black holes. It has to be just right. Luckily for us the big bang got it just right, the perfect amount of gravity.. In the turmoil of forces after gravity emerged, still a fraction of a second after the big bang, a shock wave of energy erupted and expanded the universe in all directions at incredible speed. All of space expanded by an unbelievable large factor in a fraction of a second. We think that in a millionth of a millionth of a millionth of a millionth of a second space expanded by a factor bigger than a million million million times….And that’s faster than the speed of light. But doesn’t that break one of the laws of physics ?…Even school children know you can’t go faster than the speed of light, but actually there is a loophole there because nothing can go faster than light, nothing being empty space. This idea gives the best mind in science a headache, but its critical in understanding the early universe. Scientist believe that it took a millionth of a millionth of a millionth of a millionth of a second for the universe to expand from the size of an atom to a tennis ball. That may not sound like much. but its like a golf ball expanding to the size of the Earth in the same amount of time. That means it was expanding faster than the speed of light…..So many things were happening so fast in the early universe because everything was so close together that we need a new unit of time to describe things….Its called Planke Time.

To understand just how short Planke Time is, consider this, there are more units of Planke Time in one second than all the seconds since the big bang. The calculation is mind boggling. There are more than 31 million seconds in a year and its been 14 billion years since the big bang, so multiply 31 million 556 thousand 926 X 14 billion, you end up with an absolutely huge number. It’s a time scale that’s so small that all human intuition goes out the window. If we look at our watch and measure one second, we can ask how many Planke Times is that, well it is a billion billion billion billion billion Planke Times…..So now the universe is only a few Planke Times old, and a fraction of a second later, the universe is so small it can fit into the palm of your hand. But in a tiny fraction of a second it expands to the size of the Earth. Then moving faster than the speed of light it grows larger than our solar system and its still a raging storm of super heated energy…The universe is trillions of degrees hot but as it expands it begins to cool down. Dropping temperatures trigger the next stage in the universes evolution.

The raw energy of the explosion transforms into tiny subatomic particles. It’s the first matter in the universe. This conversion of energy into matter was predicted by Albert Einstein years before anyone was talking about the Big Bang. It’s the one scientific equation every school child knows, E=mc2. It says something about the universe. Even if the universe is created out of pure energy and because energy can be converted to matter and matter to energy , that you can get all of the stuff that we see in the universe from this pure energetic event…Einstein’s equation had a huge impact. It lead to the first nuclear bombs. In a nuclear explosion a small amount of matter is converted into an enormous amount of energy. As the universe was forming, the exact opposite happened, pure energy transformed into particles of matter…To create matter in the beginning , you just need energy. The energy alone can create the entire universe…In just a fraction of a second after the Big Bang the building blocks of our universe began to take shape, but this first matter is nothing like we see today. There were no atoms yet, but there were tiny subatomic particles. That earliest matter was too unstable to start forming the universe as we now know it. Think of it like this, imagine rush hour in any city in the world as that super heated universe, the commuters racing through the main concourse are subatomic particles…..If you look at that crowd of people, they may appear random, and that random quirky motion is very similar to what was happening to the particles in the universe in the earliest moments of the Big Bang.

The extreme temperature of the early universe energises the subatomic particles, they appear, they disappear, they race around at incredible speeds, its pure chaos. As the universe cools down the particles get slower and slower and become less random. As the universe cools, the particles stop changing back into energy. Now there are more and more subatomic particles, but its still a hot violent place. All this is happening in fractions of a second, too small to detect, but now the Big Bang is moving into a critical stage, a titanic battle between matter and the one thing that can destroy the universe even before it gets started, anti matter…..Everything in the universe is made from matter, from the smallest rock to the largest star, and all the matter that there will ever be was created from the pure energy of the Big Bang. Einstein’s equation E=mc2 says that energy transforms into matter. But it was just a theory. Today science is able to test that theory.

The worlds largest machine, the Hadron Collider is the size of a city, and engineered to recreate the condition millionths of a second after the Big Bang…Its designed to take us back to those earliest seconds after the big bang. It’s a 3.8 metre wide, concrete lined circular tunnel, 27 kilometres around. The collider makes tiny particles of matter smash into each other at almost the speed of light. For a split second those collisions generate turbo charged energy, similar to the explosive force of the Big Bang. And then that pure energy, briefly transforms into matter just like it did nearly 14 billion years ago. But this huge machine needs an enormous detector to see these collisions. The particles of matter are there for only a split second and move so fast it can only record their trails. Scientists hope that it will reveal just how energy transforms into matter, but not just any matter. The type of matter that emerged nearly 14 billion years ago at the dawn of time itself. But the dawn of time was a critical moment in the birth of the universe because pure energy produced one of the most dangerous things in the universe, anti matter. Anti matter is the mirror image of ordinary matter, however matter has one charge and anti matter has the opposite charge. If there was an anti me, we would look alike, no telling us apart, but if I went and shook his hand we would blow each other up in a nuclear explosion…Matter with a positive charge clashes with anti matter with a negative charge. The fate of the universe hangs in the balance of this battle. Equal amounts of matter and anti matter will cancel each other out, and its not good. A universe with equal amounts of matter and anti matter is equivalent to a universe with no matter at all, because the matter and anti matter will destroy each other back into pure radiation, and there will be nothing interesting, no stars, and galaxies and people in between…It was a cosmic battle, and the side with the most forces would win. It was very close, but there was one winner. For every billion particles of anti matter, there were a billion and one particles of matter. That was the moment of creation. The one extra particle of matter in each little volume survives, survives enough to form all the matter we see in the stars and galaxies today…One in a billion may sound like not much, but its enough to build a universe. Believe it or not everything you see around you, the atoms of your body, the atoms of the stars are nothing but left over’s, left over’s from this ancient collision between matter and anti matter. Could anti matter still exist ? In the laboratory today we have created anti atoms, anti electrons going around anti protons to create anti hydrogen…Anti matter by itself is harmless, its only when it comes into contact with matter when the fireworks start.
Give or take a couple of Planke Times the universe is nearly a second old and still a very strange place. But matter has won the battle with anti matter, and now its time to build the universe. Its still extremely hot and expanding incredibly fast. As temperatures continue to cool and the primitive particles start slowing down, they start bonding together to form the atoms of the first elements. The first one to form is Hydrogen. Then over the next three minutes the universe begins to create to more elements, Helium and Lithium…In that short period we went from creating the universe to ultimately the creation of matter. We went from a universe that was infinitely small to a universe that was light years in size. In those first three minutes everything interesting that was going to happen in the universe, happened. However we wouldn’t have been able to see it. When we look into the night sky we see billions of years into the past. We think its always been that way. Nope, not true. 387 thousand years after the Big Bang, that’s when the universe began to be transparent, before then it was milky…There was a dark milky soup of Electrons. The young universe has to cool down enough for the Electrons to slow down and stick to atoms. It took a long time for Hydrogen, Helium and Lithium atoms in the universe to form. Scientists have calculated it took about 387 thousand years for the Electrons to slow down enough so that the universe could start mass producing atoms. When that happens the milky fog clears. The first light escapes and races across the universe.Nearly 14 billion years later two young scientists in New Jersey pick it up by accident…

In 1964 two scientists were mapping radio signals across our galaxy. Everywhere they searched they picked up a strange background hum. They first suspected their equipment. But after cleaning the antenna, the strange hum remained. The strange hum was in fact the moment of creation. Nearly 14 billion years ago when those first atoms got their electrons. That’s the moment when the milky cloud clears and the new universe comes into view for the first time.
Our universe is now 387 thousand years old and trillions and trillions of miles across, clouds of Hydrogen and Helium gas float through space. It will take another 200 million years before those gases create the first stars. The universe then began to glow in majestic fashion. One billion years after the big bang the first galaxy forms. Over the next eight billion years many many more take shape, then about five billion years ago in a quiet corner of one of those galaxies gravity begins to draw in dust and gas. Gradually they clog together to give birth to a star, our Sun. Nine billion years after the Big Bang our solar system springs to life, and with it planet Earth. Since the universe was created its been expanding, filling the space with galaxies, stars, planets and moons. We may never know if the Big Bang created a universe that goes on forever, but the universe is not slowing down, but in fact speeding up.
Everything that makes us human, the atoms in our bodies, the jewellery we wear, all the things that lead to the tragedy of life, the beauty and excitement, love, every thing else rose because of processes that happened nearly 14 billion years ago. And if we really want to understand ourselves at some fundamental level we really have to understand the Big Bang.
14 billion years ago the Big Bang created time and space, our whole vast universe and every thing in it, including us. Some people ask the question, “What’s in it for me “. The Big Bang gave us everything we see around us, the distribution of galaxies and stars and even the laws of physics were born at the instant of creation. Everything started with the Big Bang, one brief moment in time 14 billion years ago that contains the answers to the greatest questions about our past, our present and our future. Each discovery brings us one step closer to understanding how the universe works, and it all started with the Big Bang…………

Last Updated on Saturday, 31 July 2010 22:54

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