Wednesday, November 02, 2005

The Cyclic Theory

A new paradigm

In 2003 Steinhardt from Princeton and Turok from Cambridge published their landmark paper on what will be the next paradigm: the cyclic theory.

Here are its salient features:
- space and time exist forever
- the big bang is not the beginning of time; rather, it is a bridge to a pre-existing contracting era
- the Universe undergoes an endless sequence of cycles in which it contracts in a big crunch and re-emerges in an expanding big bang, with trillions of years of evolution in between
- the temperature and density of the universe do not become infinite at any point in the cycle; indeed, they never exceed a finite bound (about a trillion trillions degrees)
- no inflation has taken place since the big bang; the current homogeneity and flatness were created by events that occurred before the most recent big bang
- the seeds for galaxy formation were created by instabilities arising as the Universe was collapsing towards a big crunch, prior to our big bang

Why a new theory? For different reasons, but one very important one was the fact that the universe is accelerating.

Now in the Big Bang Theory (BBT), one uses the analogy of sending a rocket into space. To do that, one must calculate the escape velocity of the rocket. What we do is to look at its total energy, its kinetic energy – how fast must it go – and its potential energy – due to the attraction of the Earth on the rocket. To escape the Earth’s gravitational attraction, we calculate that the rocket’s energy at infinity will be zero.

½m(v squared) + - GMm/R = 0

Where: v is the escape velocity of the rocket
m is the rocket’s mass
M is the Earth’s mass
R is the Earth’s radius
G is a universal constant in Newton’s law of universal gravitation

All values are known except for the escape velocity, which can be worked out from the above equation.

v = sqrt(2GM/R) or v = sqrt(2gR) , Where g is acceleration of gravity on the earth's surface.

The value of v is approximately 11100 m/s (40200 km/h or 25000 mi/hr).

Now the BBT uses this notion to look at how the galaxies are moving away from each others. Notice in this calculation that after attaining escape velocity, the rocket will go to infinity with zero velocity. Should we launch the rocket with a velocity less than that, it will fall back to earth. If its velocity is greater than this escape velocity, it will reach infinity with some velocity to spare. But in none of these scenarios, the rocket – after attaining its escape velocity – will it be accelerating. Now in the BBT, the big bang, when all the matter in the universe was launched into space – the mechanism is obscured about how this would be done – that is comparable to the launching of the rocket. So the question was: did the galaxies have enough velocity to escape? If yes, the universe would expand forever and die in a wimp. If not, the universe would eventually reverse course and die in the big crunch. But when it was found out that the galaxies were accelerating that brought major headaches to the theory. One way out was to postulate Dark Energy. But this ad hoc hypothesis was like doing some patch work. Science doesn’t like patch working, it wants a comprehensive theory. The cyclic theory is one such theory that seems to have a lot of wind in its sails.



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The Mad Scientist said...

I personaly have found that the big bang (and the T zero assumption) to violate too many conceptual principles. Where did the mattter/energy come from?

This cyclical universe would resolve these issues.

And good to see that you've now blocked anonymous comments!

kamjin said...

let's forget about big bang or cyclic theory, wether the two of them are possibilities; if the universe is still expanding, there's a possible violation of one golden law: (supposedly) nothing can travel faster than the light, if we take this as true, is the universe border expanding slower than the light? if so, it will be a time where the light of the galaxies will reach the boundary, and the question is: what will it happen then?
will light be absorbed by the boudaries? (taking that light cannot escape this universe), will it be reflected? if it is absorbed, will this result in the increase of the residual energy we detect that is around 3K?; now in the other hand, if we take the cycling theory, what will it happen when the amount of energy (carried by photons) reach the boundaries? clearly this will slow down the big crunch... a third possibility (these are all mere conjetures by someone out of his mind and with lots of spare time as i can see), WHAT IF light is allowed to escape the universe? (after all, there's no theory as far as i know, of what happens to light while it travels trhough space, is it slowed down?, if so, big crunch would be confirmed indirectly, i think) if light that reach the universe's boundaries could escape the universe (taking the right amount of time, of course), that would mean that the universe is cooling down on time, and it would reach an end after several cycles; i think this is a really incredible mind-blowing matter of astrophysics, personaly i really like all of this, but havent been in touch with those theories...

Robert said...

Rob MacRiner ,

Answer to Question: Why does time seem to exist only in a forward direction?

Time seems to only exist in a forward direction because the universe is expanding. If the Universe reaches Critical Velocity and starts to contract ....then time, as we measure time will reverse according to the Big Bang / Big Crunch Theory. The reason for this is that time does not exist without change or movement..... (change or movement of particle matter or energy as we know it). If matter has no movement either expanding or contracting then time does not exit for that matter. However Time can exist around non moving particle matter if something is either expanding or contracting around it.

If the expansion of matter increases as in the case of our universe, or an expanding object, or even light...then time increases relative to the rate of expansion. Example: if carbon A is heated and expands faster than carbon B (which is not heated) then time increases in carbon A relative to carbon B...However as Einstein pointed out...time is relative to the observer...and you need something of contrast to make that comparison....fortunately our universe offers lots of contrast ...otherwise we would have a very difficult time figuring this out. Time being relative to the observer can exist at different speeds based on the rate of expanding matter. If you are on riding on a beam of light than time is much different than your friend riding on a sound wave. Of course time is relative to the observer, therefore your time is much faster only to him, or any body else who is not on a beam of light.

If matter contracts or condenses then time actually reverses…as in the case of a contracting universe…so Planks Quantum would be measured as zero time for the entire Universe…and time starts at the point of the Big Bang (once matter is on the move again)… In the case of a Black Hole, relative to our expanding universe)... there is also no time. (except for matter being sucked into a Black Hole….this matter would be reversing in time, until at which point it becomes part of the Black Hole mass, then time (in a Black Hole) as in Planks Quantum is zero….which is odd because the Universe is still expanding around the Black Hole…but it is consistent with the theory that. Time can exist around “non moving matter” if something is either expanding or contracting

Time as we know it is measured in a forward direction and will continue until the point of critical velocity…at which point time starts to reverse…and for a brief moment…the point where the Universe changes from expanding to contracting…time will again be zero…as in Planks Quantum. However…during the forward direction of time…(while the Universe is expanding)…Black Holes are continuing to suck up matter…and should in theory at some point converge with other Black Holes….Therefore…as the universe is expanding from the Big Bang…there is multitude of matter which is not expanding (Black Holes)…which might well be unexploded Planks Quantum matter from the Big Bang…and the Black Holes with their massive gravitational force are sucking up matter which was attempting to expand but was not able to overcome the stronger force of the Black Hole…like mini-Plank Quantum’s converging within the universe …When the Universe reaches Critical Velocity and then all matter in our Universe starts to contract…heading towards the Big Crunch….the multitude of Black Holes converging (up to that point) should in theory rapidly increase the speed of reverse time …acting as an accelerant force of a contracting Universe with their collective gravitational force …So the reverse of time.(the journey the contracting Universe is taking towards the Big Crunch)...should happen much quicker than the time it took for the Universe to go from the Big Bang to Critical Velocity…That is of course Time relative from the Big Bang to Critical Velocity ……in contrast to …….Time Relative from Critical Velocity to the Big Crunch. Mathematically it might be possible to estimate this time.… Rob MacRiner Nov 2007