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Name: Donus
Status: other
Grade: other
Location: NV
Country: N/A
Date: N/A


Question:
Will stars ever get together? If they do will, an explosion happen which will start the universe all over again?


Replies:
Hi Donus,

The theory of the "Big Crunch" has been proposed before and is a very attractive theory - it would mean that the universe is inherently infinite (it goes through a continuous series of birth, death and rebirth).

However, we currently do not have data to support this theory. In order for the Big Crunch to occur, there must be sufficient mass in the universe to produce the gravitational attraction to get galaxies and stars moving toward each other. Right now, we are missing about 2/3 of the required mass to start the Big Crunch.

Also, there is some evidence that not only is the universe expanding, but it is expanding at an accelerating rate. This surprising data makes the Big Crunch more of an improbability.

We may yet find the needed mass in dark matter or singularities, but for now we have to go by what the data says and say that the Big Crunch is unlikely.

Greg (Roberto Gregorius)


Dear Donus,

Thanks so much for your good question. Your student has a point, although he or she is confusing stars with superclusters of galaxies, which are several orders of magnitude bigger and more powerful. IF (there is evidence to the contrary) the pulsating theory of the Universe is correct, then at some point in the far off in the future, the expansion will slow, stop, then reverse itself to a "big crunch."

Within a galaxy, stars do not move towards each other, just orbit the center of the galaxy.

Sincerely

David H. Levy


First of all, it is not entirely certain that the Universe will NOT eventually come together into a "Big Crunch." That is one possible end for the Universe.

That said, his premise is incorrect. Most of the galaxies are moving AWAY from each other right now. For them to start moving together, they first must slow down, stop, and then reverse direction. Current observations make cosmologists doubt that there is enough gravity for that to ever happen.

I am not a cosmologist myself, so I cannot comment on what would happen to the universe after a Big Crunch.

Richard Barrans, Ph.D., M.Ed.
Department of Physics and Astronomy
University of Wyoming


First, a short lecture to your student. What you are proposing is NOT a "theory". It is a "conjecture", or a "speculation". A "theory" is a set of principles (the fewer, the better the theory) that explains a wide variety of experimental past observations and makes predictions about what will be observed by experiments, not yet done, regardless of the topic of the "theory". Two "classic" examples are Maxwell's equations of electromagnetism, and Darwin's treatment of the evolution of species. A "theory" is the highest form of recognition scientists give to the treatment of a topic.

Note however, "conjectures" are not bad. They are the "stuff" that laws and theories are made of. The "conjecture" or "speculation" makes no promises. They just say, "Let us run this up the flag pole and see if anyone salutes."

Two recent examples:

"Faster Than the Speed of Light" by Joao Magueijo. He poses the question: "What if the speed of light (in a vacuum) is not constant, but can travel faster/slower than its traditional value, which in traditional physics is a "fixed" number. Be aware that the author is not some "off the wall" nut. He is professor of theoretical physics at Imperial College, London. He has been visiting scientist at the University of California, Berkeley, and received his doctorate in theoretical physics at Cambridge University. So his credentials are impeccable. When someone of that stature asks the question, "What if???" scientists (sometimes not very friendly scientists) take notice. The conjecture remains neither supported or rejected at the present time, but the point is that it challenges thinking.

"The Deep Hot Biosphere" by Thomas Gold is another example. He was an acclaimed astrogeologist, cosmologist, astronomer, among other fields -- a member of the National Academy of Sciences (U.S.). He taught at Cambridge (U.K.), Harvard, and Cornell. He died a few years ago. He speculates that traditional models for the generation of "fossil" fuel (oil, coal) are incorrect, and deep within the Earth's surface there is methane (CH4) in large amounts.

Why have I gone into this detail on an example that is not "on target"? The reason is this: "What are the data?" The data to date, is that the Universe is expanding. This is pretty well established by raw experimental data -- look up Doppler shift -- for details. But there is a problem. When the distance between galaxies, which in current theory is age, is not expanding as fast as current models (note I did not use the term "theory") of the Universe predict.

So your student's conjecture that stars, and therefore collections of stars (i.e.) galaxies, are getting closer, is not supported by the best current data. What appears to be happening is that the RATE of expansion at long distances (i.e.) older time is not as fast as the "Standard Model" predicts.

That is not a small problem!! I think it would be more productive to help explore your student's conjecture. I know that means a lot of work for you.

"I know it is not possible but I do not have a point to argue back to his theory and prove him wrong. Please give me a point that I can argue back with." I cannot give you such a point to "prove" him wrong. His data, stars approaching one another, does not seem to fit our best present data, but do not make it a contest between your student and you, right or wrong. Rather, make it an opportunity to explore.

For example: What stars are colliding -- there have to be many to support your student's conjecture. How does his conjecture address the experimentally well established expanding Universe? If stars collide, their composite mass is of the order of the sum of the two. Can the "lost" mass be observed? The collided stars have a mass that is roughly the sum of the two. Are there any effects on neighboring stars? My point, possibly too detailed, is to turn the problem into an exploration, not a confrontation.

Our view of the Universe is on rather debatable grounds right now, so don't become too dogmatic. The "answer" is not on the table just yet. Your student may be right!!

Vince Calder



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