Tuesday, May 1, 2012

The Big Bang

The theory of the Big Bang is based on the assumption that once the universe with all its matter, energy and  pace was concentrated in a single point. Then it exploded in a Big Bang and during the following 13.7 billion years it formed the universe that we can see today with its planets, stars, galaxies and galaxy clusters.
It is today the most widely accepted theory about the origin of the universe and replaced earlier theories like for example the steady state theory, which assumes that the universe has more or less always been as it is today and has neither a beginning nor an end.
Although the Big Bang theory is today so widely accepted, it has still its problems that it cannot explain so easily. However scientists have always come up with new adjustments to this theory in order to save it from being falsified by actual observations.

First Problem: Missing Matter (Flatness Problem)
In order to determine the future fate of the universe, scientists wanted to measure the concentration of matter in space. If the amount of matter in the universe was more than a certain value, the universe would one day stop to expand, when the gravity of its matter would get stronger than the force that caused the Big Bang and its expansion. The process would then reverse and the universe would collapse in a Big Crunch. Would the amount of matter be lower than a certain value, it would forever continue to expand, since the gravity would never be enough to stop its expansion.
The third possibility was that the amount of matter would exactly be that value to be able to stop the expansion, but not enough to reverse it. In this case the universe would slowly approach its maximum extension, without ever reaching it or surpassing it.
Observations of the Hubble telescope finally allowed an estimation of the amount of matter in the universe. And the result was that the amount of matter was not just lower than the value needed to stop its expansion it was far lower. It was so low, that it couldn’t even explain, why the universe hadn’t exploded long ago and was still merely compact. In fact the amount of matter found was about 17% of the amount needed to explain how the universe would have survived for so long after the Big Bang. So the theory of the Big Bang was in big trouble.
But some ingenious scientist came suddenly up with the creative idea, that if there was not enough matter in the universe to support the Big Bang theory, there had to be some invisible matter that simply could not be detected. This matter was called with the mysterious name "Dark Matter".
No scientist can actually explain, what this Dark Matter is supposed to be, and why it is undetectable, although it makes for more than 80% of matter in the universe, but they came up with vast number of theories like Black Holes, neutrinos, "Dark Energy", or simply a hidden variable of space or gravity.
However thanks to this unproven speculation about Dark Matter or Dark Energy the Big Bang theory is still alive.

Second Problem: The Universe is too Big. (Horizon Problem)
Since nothing can move faster than light according to Einstein’s theory of Relativity and the Big Bang is supposed to have occurred about 13.7 billion years ago, there shouldn’t be any objects in the universe, which are more than 13.7 billion years away from each other. Unfortunately for the Big Bang theory, this is not how it is. There have indeed objects been observed on opposite sides of our horizon to be farther away from each other than light speed would permit. Once again the Big Bang theory was threatened. But scientists were quick to find a solution for this problem. They assumed that there was a phenomenon called "inflation" just shortly after the Big Bang when for some strange reason the universe expanded faster than light. The so called "Inflation" theory so once again saved the day for the Big Bang theory, although it created even more questions than answers. Simply introducing new parameters into an equation that have never been observed anywhere else is a very bad style. Apart from the "Inflation" theory there has never been any observation to support the assumption that space would be able to expand faster than light.

Third Problem: Where is the Antimatter? (Baryon Assymetry)
If all the matter in the universe was created during the Big Bang from an extremely hot state out of energy, then for every particle there must have been created its anti-particle. Elementary particles cannot be produced without producing their anti-particles. This means that there must be the same amount of matter and anti-matter in the universe. On the other hand the observation of the universe shows that there is no anti-matter in the observable part of the universe. Since matter and anti-matter would annihilate each other if they ever meet, there would need to be a vast amount of space between them. It can be calculated that in the whole universe there is no such area of empty space. Until the present day not even a single anti-helium atom has ever been observed, neither in space nor artificially created in a particle accelerator.
Therefore the matter of the universe cannot have been created by the Big Bang, if we don’t want to give up all the elementary principles of elementary physics and quantum physics.
So far even the scientists who support the Big Bang theory haven’t found a theory to explain this problem away. Some speculate about the CP symmetry of elementary particles being somehow incomplete (anti-particles having distinct properties from normal particles) without realizing hat they are questioning the basic laws of nature that hold our universe together as it is.
In fact the anti-matter problem is simply ignored when talking about the Big Bang and its solution is postponed.

Forth Problem: Objects older than the universe? (Globular Cluster Age)
Although the age of the universe has been calculated to be 13.7 billion years, the globular star clusters surrounding our galaxy seem to be at least 15 billion years old considering their star population.
This problem caused an immediate headache to all scientists supporting the Big Bang theory. But they saw their chance. The difference between the age of these star clusters and the age of the universe was rather small, so it was an observation, which could be discussed away with enough effort. And finally in the late 1990s they had had done enough fine tuning in some computer models, so that they turned out a younger age for the globular clusters. The results of these computer simulations are still disputed and it is obvious that the scientific method had been reversed in this case. The desired result of these simulations predated the actual experiment and had obviously an influence of it.  And even supposed that the results are right, there remains the question how these structures could form so early in the history of the universe.

Fifth Problem: A beginning without an end?
Since scientists found out that the expansion of the universe is increasing, instead of slowing down as one might expect due to the effect of gravity, the Big Bang theory has to assume that the universe had a beginning but will have no end, no Big Crunch. This rises first of al the question, if it is theoretically thinkable that thing have a beginning but no end. We would have a situation that an infinite and ever-increasing number of things would come into existence populating the world ad infinitum. Avery odd concept. 
However we could assume that the universe will finally come to an end when its expansion has become so fast that even the strong nuclear interaction would not be able to prevent the quarks of the baryons moving away from each other beyond their respective event horizon resulting in some kind of evaporation of the universe. This event, the so called "Big Rip" would be more than 10^{10^{76}} years in the future (a 1 with 1076 zeros, an unimaginable number for the human mind), long after the "Big Freeze" when all matter of the universe had turned into Black Holes. Then we would have to question why we are existing at a moment so close to the beginning of the universe, while we should expect to exist just in any random point of time during the lifespan of the universe. From a statistical point of view it has a probability close to zero that we live just 13.7 billion years from the Big Bang while the whole lifespan of the universe is close to infinitely longer. Even if we apply the highly controversial Anthropic Principle (that we can only exist when physical existence is  possible due to the physical conditions of the universe), there would be conditions for biological life up to 1014 years in the future. This means we would still be during the first 3 days of baby's life if we scale down the productive life of the universe to a human lifespan. This is still very improbable. 
Improbable doesn't mean impossible, but it makes the whole theory look very ugly. We should not settle for theories with a probability of less than 0.01%.     

Observations Supporting the Big Bang Theory

After reading about all these problems with the Big Bang theory one may wonder, why they came up with this theory in the first place.
Indeed there is currently no better theory about the origin of the universe and the steady state theory has its own unexplained problems, which are even more serious than those of the Big Bang.

The key observation, which led to the development of the Big Bang theory, was the red-shift of the galaxies. The light reaching earth from galaxies far away is shifted towards longer wavelength (towards the red end of the optical spectrum). This red-shift is stronger in galaxies farther away and seems to be directly correlated to the distance of the object.
This red-shift was explained with the Doppler Effect. It is known that the wavelength from a source of a wave moving away from an observer is stretched longer than the wavelength from a wave with a source, which doesn’t move. We can hear this effect when a ambulance car is driving past us. First the siren sounds pitched. Then when it passes the closest point and moves away the sound seems to have a lower frequency.
The same would happen with light emitted from a moving object. Since the light of all galaxies has a longer wavelength then expected, they seem to move away from us. The only logical explanation was that earth would either be the center of the universe, from which everything moves away, which is rather unlikely, or that the universe itself expands creating more empty space between the galaxies.
If we extrapolate this situation, there must have been a point of time when all matter of the universe was concentrated at one single point and then started to move away from each other.
This is historically the beginning of the Big Bang theory.

But what if the red-shift is not caused by the Doppler effect? Are there other explanations possible for the red-shift?
Indeed there are.
And indeed the Doppler effect is a pretty bad explanation for the red-shift, since it contradicts astronomic observations. We know for sure that galaxies don’t necessarily move away from each other. We can actually observe a huge number of collisions of two galaxies throughout the universe. Even our own galaxy is not moving away from its closest neighbor the Andromeda galaxy. They are approaching each other and will eventually collide and merge. So, if we can actually see galaxies approaching each other and organizing in huge clusters and super-clusters, then this means the gravity between them is stronger than any other force, which is supposed to pull them away from each other. Our own galaxy and the local group are part of the Virgo super cluster. So why should they move away from each other, if they are obviously organizing themselves into super structures due to their gravity?
No, the Doppler effect doesn’t convince as an explanation for the red-shift of the galaxies.
What other explanations are possible then?
A red-shift means that the light reaching us from other galaxies has obviously lost energy, since the wavelength is reciprocally proportional to the energy of light. This means red light has less energy than violet light for example. But there are many explanations possible for this loss of energy. It actually seems quite logical that light would lose some energy on its long way to us. Although space seems to be empty, it is not an absolute vacuum. There is still some intergalactic matter between the galaxies in very low concentration, but nevertheless there is. And any interaction between the light and the matter between the galaxies would naturally result in a loss of energy, which would be given to the matter particles between the galaxies. What we would see in such a case is exactly the same red-shift that we can see today, and which was may be wrongly attributed to the Doppler effect.
The possibility that photons may not be that stable as we think, may also be considered. What if photons slowly decay in other photons with lower energy or other low-energy particles?
This loss of energy, no mater what its cause may be, would continue until the photon has reached an energy as low as the average energy of the universe, resulting in a diffuse background radiation. And this is exactly what we see. However the Cosmic Microwave Background Radiation was interpreted differently in order to support the Big Bang theory.

Cosmic Background Radiation
Since the Cosmic Background Radiation was discovered in 1964, it has been considered the ultimate proof for the Big Bang theory, which had predicted it. It is a homogenous glow coming from every direction with a wavelength in the microwave spectrum equivalent of a thermal black body spectrum at a temperature of approximately 3 K. It is considered to be the remnant of the Big Bang, which has now cooled down to a temperature of 3 K.
Nevertheless the assumption that light emitted from galaxies far away loses energy on its way to us results in exactly the same prediction, so it is no proof for any of these theories.
In an infinite universe without beginning or end there has necessarily to be a homogenous background radiation coming from the infinite number of stars out there in any possible direction.

Why the Big Bang Theory?
Even the supporters of the Big Bang theory admit that there are still unsolved problems with their theory. But nevertheless nobody has come up with a better theory so far. The main problem of the steady-state model of the universe is the question why the entropy of the universe hasn’t reached its maximum meanwhile. In the same way the Big Bang theory can be asked why the universe has such little entropy in its beginning. But either way, there is in fact no conclusive model that could explain the origin and fate of the universe.
But why don’t we just say, we don’t know it? Why do we continue to work with a theory, which contradicts our observation?
It looks like the Big Bang theory cannot be falsified, which is part of the definition of the scientific method since Karl Popper. Whatever observation we make that contradicts this theory, some obscure new phenomenon is introduced to keep the theory alive, may it be Dark Matter, the Cosmic Inflation or violations of the CP symmetry. Scientists will cling to the Big Bang theory no matter what new observations they make.
This has little to do with science.
Why would scientists behave in such a irrational way?
There are several circumstances when we can’t trust scientists anymore. This is when politics, money, religion or social issues come in. In the case of the Big Bang theory it has nothing to do with politics, society or money. The issue is politically and socially irrelevant and can’t be turned into financial benefit.
But it has to do something with religion. And this is when the whole issue gets suspicious.

The biblical god creating the Big Bang

The Big Bang and God
Throughout human history the omnipotent gods have always been somehow hidden on remote places. This was necessary in order to make unproven claims about them and to empower a class of clerics. So gods have frst been placed on some high and remote mountains (Olympus, Mount Sinai). But some curious humans had soon verified that there were no gods.
Then they were moved to the sky above the clouds. And humans built planes and couldn’t find them there either.
Finally the god (meanwhile there was only one of them left.) was moved beyond the sky into outer space. But spaceships and telescopes couldn’t find him there either.
Next the god was placed into a hidden realm within nature where his spirit was supposed to be the driving force behind all life on earth. But the theory of the vis vitalis (life-force) crumbled and biochemistry was able to explain life without any divine interference.
Then, when there was finally no place left for the god to go, he was placed outside the universe as its creator as the cause of the primary cause of everything.
But therefore it was necessary that the universe had a primary cause, a beginning. And this is when the Big Bang theory was happily received by all those who wanted to belief in god. At last the god was safe from human curiosity in a place beyond scientific investigation. Through the Big Bang the god was able to do whatever he wanted. He could determine the primary condition of the universe, and everything what happened later would depend on it.
Therefore it shouldn’t be a surprise that the scientist who once came up with the theory of the Big Bang, Georges Lema├«tre, was also a Catholic priest.

Prelate Father Georges Lemaitre
Inventor of the Big Bang theory

So it should now be quite obvious why such a flawed theory as the Big Bang resisted any doubts and contrary observations. It will never be disproved, because those who support it are not willing to give it up. It is their last attempt to keep the idea of an omnipotent creator-god alive. Without the Big Bang there is no way how this god could fit in.
This would not make a difference for the majority of people with little or no scientific education who usually react with denial to inconvenient scientific facts, but it is a problem for the huge number of intelligent and educated scientists who also happen to believe in a god due to their indoctrination in early childhood. They depend on a rational explanation of the god and could not live without it.

Science is done by humans. So it suffers from their human weaknesses. This is why we should not have much trust in scientific results where human emotions are involved.

A final word: This article doesn't mean to state that the Big Bang theory is wrong. It only states that there is insufficient proof for this theory and that the theory is unable to explain even the most basic questions related to the nature of the universe. There is currently no better theory that I would have to offer. But this doesn't mean that we have to live with a model that contributes nothing useful to our understanding of the world. We should simply admit that currently we have no working model for the origin (if there is one) and the final destiny of the universe.

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