Tuesday 7 December 2010

The Universe: questions and theories

There is much we don’t know about the universe. There are also questions that we have that scientists seem to have answers for, at least in theory.

What constitutes the Universe?

There are two answers to that question. The first one is that the universe only comprises of material things such as atoms, gasses, dust, asteroids, moons, planets, suns and galaxies and that the furthest galaxy is the outer limit of the universe. The second answer is that the universe includes the above and extends beyond the furthest galaxy in which the space comprises of pure vacuum.

How far does that material galaxy extend?

Using the ISAAC near-infrared instrument on ESO’s Very Large Telescope, and the magnification effect of a gravitational lens, a team of French and Swiss astronomers has found several faint galaxies believed to be the most remote known. Further spectroscopic studies of one of these candidates has provided a strong case for what is now the new record holder – and by far – of the most distant galaxy known in the universe. Named Abell 1835 IR1916, the newly discovered galaxy has a redshift of 10 and is located about 13,230 million light-years away. It is therefore seen at a time when the universe was merely 470 million years in existence, that is, barely 3 percent of its current age. The universe’s current age is 13.7 billion years.

Does the universe extend beyond the furthest galaxy?

I believe that the universe includes the area beyond the furthest galaxy. As we look out into the universe, we are aware that galaxies are moving away from us faster and faster. However, galaxies are so large and so far away, we could never see them move just by looking at them even if we looked for a whole lifetime through the most powerful telescope in the world.

The determination of the expansions of the universe is based on the shift in variations of red. The element hydrogen is the most common element in the universe and it is plentiful in galaxies. This helps astronomers to investigate the speeds of galaxies by comparing the redshift of hydrogen in them over a period of time through the use of spectroscopes. Because space itself is expanding, the further a galaxy is from us, the faster it seems to be receding away from us.

One of the slower galaxies is speeding away at about 5,040,000 mph. That’s like going from one side of the United States to the opposite side in about 2 seconds, give or take a little. One of the further distant and faster galaxies is going so fast, it would take it about a second to go all the way around the world. It’s being clocked at about 93,600,000 mph.

It follows then that the material universe is constantly expanding into the void at speeds of almost a hundred million miles an hour. This has to mean that the universe includes the area in space beyond the furthest galaxy. Just how far that area of space goes, it is impossible to determine.

What is the Big Bang theory?

Since it has been established that the material universe is expanding, it follows that 13.7 billion light years ago, all the galaxies, dust and dark material were just one ball of gas ready to explode. How big was that ball of gas? According to scientists, that ball of gas was compressed to a size comparable to thousands of times smaller than the head of a pin. Quite frankly, I find that hard to believe.

My theory is that that ball of gas was at least the size of a galaxy; millions of light years across. Active galaxies are known to collide and produce massive nuclear explosions, sending jet streams of matter stemming from their centers. When two galaxies get too close to each other in their orbits, the larger galaxy, or cannibal galaxy, will frequently consume the smaller one so that the two of them become one. This being so, eventually all the galaxies will become one giant galaxy.

But if that is so, then why would billions of galaxies be compressed into the size of just one normal sized galaxy? The answer is that the galaxy would in actual fact be a giant black hole that would be much smaller than the length and width of the Milky Way as it is today.

What is a black hole?

A black hole is a region of space from which nothing, not even light, can escape. It is the result of the deformation of space time caused by a very compact mass. Around a black hole there is an undetectable surface which marks the point of no return. This surface is called an event horizon. It is called ‘black’ because it absorbs all the light that hits it, reflecting nothing, just like a perfect black body in thermodynamics. Quantum mechanics predicts that black holes also emit radiation like a black body with a finite temperature. This temperature decreases with the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass.

Scientists believe that in the centre of the Milky Way (our galaxy) is a huge black hole that is sucking in the stars around it and as it grows larger, the Milky Way and everything in it (including Earth) will just be a black hole. When all the other galaxies have each become a black hole and have collided with each other, the mass will be just one huge black hole.

Hydrogen (which is the most common element in the universe) is explosive and will still exist in black holes and at some point when all the galaxies and dust and dark matter are one huge black hole, it will explode again and the material universe will expand again just as it did 13.7 billion light years ago.

Did the material universe exist before the Big Bang?

A famous British physicist believes that the Big Bang was not the true beginning of the universe and that the material universe dies and is reborn endlessly. Last month, Oxford University physicist Sir Roger Penrose and an Armenian colleague, Vahe Gurzadyan, published a paper online arguing that the cosmic microwave background radiation that surrounds us at all times contains circular patterns of relatively uniform temperature. Mr. Penrose believes these are echoes of collisions between supermassive black holes in what he calls the ‘aeon’ before our own, a universe separated from ours by the Big Bang.

According to their theory, billions of years from now, practically nothing will be left in the old, cold and enormous universe. They say that time itself will end, because it can only exist if there are particles with mass to experience it. If there is no time, distance cannot exist either. So when the last mass vanishes, a universe that was unimaginably huge will have no size at all, setting the stage for another Big Bang.

Mr. Penrose said, “I'm saying not only was there something before, but what there was before was the remote future of a previous aeon (universe). If the idea isn't shot down by something that we've missed, this gives us a handle on things we thought we'd have no idea about.”

His paper, with the somewhat impenetrable title Concentric circles in WMAP (Wilkinson Microwave Anisotropy Probe) data may provide evidence of violent pre-Big-Bang activity with 30 to 40 microwave radiation disturbances observed so far provide evidence of Mr. Penrose's concept of Conformal Cyclic Cosmology (CCC).

This is not the first time that a theory of the universe experiencing an infinite string of Big Bangs. Earlier such theories were articulated in 1920s by the Russian cosmologist Alexander Friedmann and in the 1930s by the American Richard Tolman. Alas, its basic outline may be the most difficult to understand.

Previous theories involving cyclical universes have imagined one universe giving away to another through ‘Big Crunches’, a contraction of the universe causing everything left to collide into a nothingness, but CCC is more esoteric than that.

"People always think I'm saying the universe comes back into a Big Crunch and then gets started off again, but that doesn't work," Mr. Penrose said. Then he added, “Perhaps 10 to the power of 100 years from now; (that’s 10 with a hundred zeros behind it) a time so far away that our 13.7-billion-year-old universe would appear to be an infinitesimal fraction of a second old to that future universe's year, practically nothing will be left in the cold, diffuse and enormous universe except black holes, which will be radiating away into nothingness excruciatingly slowly.”

According to him, eventually even the black holes will ‘pop’ into oblivion with roughly the force of an artillery shell, a comically tiny whimper on the cosmological scale.

That prognosis just strikes me that this is a particularly gloomy fate for this very incredible universe of ours.

Time only exists if there are particles with mass to experience it. If there are no longer any particles with mass left in the universe, nothing exists to keep time itself, the universe's clock, ticking.

If there is no time, Mr. Penrose explained, distance does not exist either. Physicists regard time and space as being so intertwined that you cannot have one without the other. And because space is another way of saying distance, a timeless and space-less universe is a distanceless one as well. "There's nothing around to tell you how big you are," he said.

In short, when the last mass vanishes, a universe that was unimaginably enormous suddenly has no size at all. The universe grinds to a dark and immeasurable halt. "You need to have some technical mathematics to make the whole scheme fit together; you just have to look at the details. The leap of imagination here is; if there's nothing around there to measure the scale of things, big and small are really equivalent," Mr. Penrose said.

The hope for this dead universe lies in the fact that it begins to sound like the zero volume, infinite energy state that existed at the moment before the Big Bang. Mr. Penrose's self-described claim imagines one universe's corpse as another's embryo.

Now the thing to get your mind around, of course, is how can this little tiny squashed-up space at the Big Bang, enormously hot and enormously dense, be matched with the completely opposite state; enormously cold and enormously spread out?

Bill Unruh of the University of British Columbia has listened to Mr. Penrose's talks, he wrote in an email this week that he understands the CCC concept to mean that the universe eventually forgets all scales; that is, distances, and all scales, instead of being immensely large become immensely small, and another Big Bang starts again.

Prof. Unruh's UBC colleague Douglas Scott is likewise unconvinced by the arguments in the latest paper and he also doubted the evidence for radiation speaking to us from a previous universe. He said in his email, “If this was true it would be truly astonishing, and one of the most significant results ever discovered about the cosmos. Unfortunately, there are several problems with the claim.” He said that he has difficulties with the way Mr. Penrose and Mr. Gurzadyan interpreted the WMAP data. He added, "The bottom line is that the result would be astonishing if it showed that there was structure before the Big Bang imprinted on the sky."

David Spergel, a Princeton University cosmologist who has helped Mr. Penrose examine the cosmic microwave background radiation for a whisper of old universes, complained to Science News magazine that while the ripples would seem to be in step with the CCC concept, the paper lacks enough technical detail to evaluate the claims about them.

Mr. Penrose’s search for ripples in the cosmic microwave background radiation began with a brainstorm about what elements of a previous universe could possibly intrude into our present one.

He hypothesized that radiation from the collision of supermassive black holes in the last universe would still be around to ‘kick’ and disturb the canopy of microwave radiation created in the opening second of our current universe. He said, “What I imagined was something like rain falling on a pond, and each drop of rain causes this ripple going out.”

Because black holes are likely in an old universe, to pile up in multiple collisions that unfold over long stretches of time, Mr. Penrose expected to see sets of rings in the radiation glow centred around the sites of multiple collisions.

Mr. Gurzadyan believed he could see them in a dozen places in the sky. Where there was one ring there was always at least one more, and sometimes as many as five altogether.

As elated as this left Mr. Penrose, it will take much more persuasion and evidence before other cosmologists will see the same thing (assuming they ever do), and he knows it. Once an advocate of the now-discredited ‘Steady State’ theory of the universe, the 79-year-old believes that cosmological models themselves are born, live and die in an apparently endless succession.

Religious beliefs

Religious believers eager to square their faith with the latest theories in physics will closely follow the debate around whether the universe began with a single Big Bang 13.7-billion years ago, or has experienced many universes, each starting with its own Big Bang. Certain Christian denominations that do not insist on the Bible being literally true, notably the Roman Catholic Church, have tended to be fairly comfortable with the idea of the existence of the Big Bang.

The theory was actually proposed in the 1920s by a Catholic priest (the Belgian Georges Lemaitre) who was also a physicist. He believed in the concept that a universe begins with an explosion from a seemingly inexplicable singularity conformed, from a certain point of view, with Saint Thomas Aquinas's proof that God must exist because an ‘uncaused first cause’ has to have come before anything else. Hence the Vatican's blessing, as it were, for the theory.

Traditional Indian cosmological concepts have agreed with CCC that the universe is endlessly destroyed and created again, with many Hindus believing each cycle represents a day in the life of the creator deity Brahma.

My own theory

It is my belief that because the universe were are currently in is expanding, there had to be a time when it began with all the material that makes up the universe being all in one huge black hole. By extrapolating back in time, it had to start with a big bang. However, I don’t believe that the universe was in a compressed state that was so small; it couldn’t be seen by the naked eye. I believe that it began as a very large black hole that had a previous material universe inside it and that because of the pressure inside the black hole, it finally exploded and then expanded out into space at an incredible speed and is still expanding at an incredible speed.

I further believe that eventually, the universe we are currently in will have expanded as far as it can and then will begin retreating backwards towards the center of space. As it retreats backwards, the galaxies will get closer to one another and the stars will get closer to the planets orbiting them and finally engulf them. Then billions of years later, all of the material in the universe will be one big black hole and sometime later, it too will explode again and another new universe will begin expanding just as our current one is and just like the ones before it did.

If I am wrong and the universe we are in simply continues expanding for ever, then this also means that the planets will get further away from the suns that they orbit and Earth as we know it, will enter the ice age again and remain like that forever.

No matter how we look at it, our distant future as human beings looks pretty bleak. However, I wouldn’t plan on buying extra sun lotion if the universe is deflating or extra winter clothing if it keeps on expanding because until either of those two events occur, we as human beings will be around for billions of years yet.

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