- 07 Nov 2003 07:12
#42220
I don't know if many of our forum members have read A Brief History Of Time, by Dr. Stephen Hawking, but if you haven't, and have an interest in atro-physics, then I highly recommend it.
The most intriguing topic which is discussed in this book is the fate of our universe. For those of you unfamiliar with this, I'll try to put it as simply as possible:
As the saying goes "everything that has a beginning must also have an end," this may also be true for our universe. Our universe originiated from a phenomenon which is referred to by science as the "Big Bang." Although it is not known what caused this event to occur, it is known that it indeed happened. Edwin Hubble measured the wavelength of light eminating from various stars viewable from Earth. He noticed that some stars which were known to be composed of the same gasses, were emiting different wavelengths of light. This was very confusing, as gasses which fuel the fusion of a star each emit a unique wavelength of light.
The Doppler effect is another phenomenon which effects the wavelength of sound as perceived by a stationary object, while the source of the sound is in motion. For example, if a car is coming toward you at a high rate of speed, the sound of that car will appear to be higher pitched, then when it passes you and starts to move away--in which case it will now sound lower pitched. The Doppler Effect also holds true not only for sound waves, but also for light waves. If a source emitting light is coming toward you at a high rate of speed, the wavelength of that light will increase, thus appear to be more blue, and as the light passes you and moves away, the light coming toward you will look more red. The reason colors apply is because on the light spectrum, red has the lowest frequency (or longest wavelength, since the speed of light is constant), and violet or blue has the highest frequency (or shortest wavelength).
After applying the Doppler Effect to his findings, Hubble realized that, in fact, all stars were not only moving away from the Earth, but also away from eachother. This meant that the universe was expanding in every direction. However another discovery added a unique twist to his findings. The further a star was away from the Earth, the more red shift it had from it light. This meant that not only were these stars getting farther apart, but that as they got farther their rate of expansion increased. This rate of expansion was aptly dubbed the "Hubble Constant."
(The best analogy for this expansion of the universe can be likened to a loaf of bread. When you place the dough in the oven, every point in that loaf will get farther and farther from every other part of that loaf, until it is done baking.)
This discovery is perhaps the best evidence that the Big Bang indeed occured. A massive explosion would create an effect on the contents of the universe itentical to what we are indeed observing. Science has discovered the origin of our universe, but what will its fate be?
In the book "A Brief History Of Time," Dr. Stephen Hawking discusses the many possibilites of how our universe might "end up."
The first theory is popularly referred to as the "Big Crunch." In this instance, it is believed that the amount of matter existing within our universe, combined with the force of gravity from that matter, will not allow the universe to expand indefinitely. In fact, it is believe that in this instance, the rate of acceleration of the expansion of the universe will eventually cease, and reverse-acceleration will begin. It is believed that the universe will, from this point, begin to shrink, and (eventually) compress into one point in space. This point will be characteristic of the singularity of a black whole. A singularity is a point in space which is infinitely small, and yet, infinitely dense.
The second theory envisions a universe which does not contain enough matter to overcome and counter the acceleration of expansion of the universe. In this instance, the universe will continute to expand indefinitely. At a point, every particle will be so far away from every other particle that the universe will (to put it simple) "freeze." Because all sources of energy, and all forms of matter, are so far from eachother, nothing will be able to surive--not galaxies, not solar systems, not stars, not planets, not anything. The universe will become an infinite expanse of vastly spaced points of matter and energy.
The final theory presents a state of equilibrium for the universe. If the amount of matter, combined with the force of gravity from that matter, is equal to the force from the Big Bang, then the universe will expand for a time, until it eventually stops expanding completely. However, it will not being to shrink, as stated in the second theory, because the force of gravity has reached a state of equilibrium with the force of the Big Bang.
So what fate do you believe will come to pass?
Some trivial theories exist, such as the existance of "dark matter" and "dark energy," which (if proven true) could drastically effect the fate which will occur. However these two theories are for another discussion, and at another time, for I am thoroughly exhausted from describing all of this. Anyway, I hope you enjoyed it!
The most intriguing topic which is discussed in this book is the fate of our universe. For those of you unfamiliar with this, I'll try to put it as simply as possible:
As the saying goes "everything that has a beginning must also have an end," this may also be true for our universe. Our universe originiated from a phenomenon which is referred to by science as the "Big Bang." Although it is not known what caused this event to occur, it is known that it indeed happened. Edwin Hubble measured the wavelength of light eminating from various stars viewable from Earth. He noticed that some stars which were known to be composed of the same gasses, were emiting different wavelengths of light. This was very confusing, as gasses which fuel the fusion of a star each emit a unique wavelength of light.
The Doppler effect is another phenomenon which effects the wavelength of sound as perceived by a stationary object, while the source of the sound is in motion. For example, if a car is coming toward you at a high rate of speed, the sound of that car will appear to be higher pitched, then when it passes you and starts to move away--in which case it will now sound lower pitched. The Doppler Effect also holds true not only for sound waves, but also for light waves. If a source emitting light is coming toward you at a high rate of speed, the wavelength of that light will increase, thus appear to be more blue, and as the light passes you and moves away, the light coming toward you will look more red. The reason colors apply is because on the light spectrum, red has the lowest frequency (or longest wavelength, since the speed of light is constant), and violet or blue has the highest frequency (or shortest wavelength).
After applying the Doppler Effect to his findings, Hubble realized that, in fact, all stars were not only moving away from the Earth, but also away from eachother. This meant that the universe was expanding in every direction. However another discovery added a unique twist to his findings. The further a star was away from the Earth, the more red shift it had from it light. This meant that not only were these stars getting farther apart, but that as they got farther their rate of expansion increased. This rate of expansion was aptly dubbed the "Hubble Constant."
(The best analogy for this expansion of the universe can be likened to a loaf of bread. When you place the dough in the oven, every point in that loaf will get farther and farther from every other part of that loaf, until it is done baking.)
This discovery is perhaps the best evidence that the Big Bang indeed occured. A massive explosion would create an effect on the contents of the universe itentical to what we are indeed observing. Science has discovered the origin of our universe, but what will its fate be?
In the book "A Brief History Of Time," Dr. Stephen Hawking discusses the many possibilites of how our universe might "end up."
The first theory is popularly referred to as the "Big Crunch." In this instance, it is believed that the amount of matter existing within our universe, combined with the force of gravity from that matter, will not allow the universe to expand indefinitely. In fact, it is believe that in this instance, the rate of acceleration of the expansion of the universe will eventually cease, and reverse-acceleration will begin. It is believed that the universe will, from this point, begin to shrink, and (eventually) compress into one point in space. This point will be characteristic of the singularity of a black whole. A singularity is a point in space which is infinitely small, and yet, infinitely dense.
The second theory envisions a universe which does not contain enough matter to overcome and counter the acceleration of expansion of the universe. In this instance, the universe will continute to expand indefinitely. At a point, every particle will be so far away from every other particle that the universe will (to put it simple) "freeze." Because all sources of energy, and all forms of matter, are so far from eachother, nothing will be able to surive--not galaxies, not solar systems, not stars, not planets, not anything. The universe will become an infinite expanse of vastly spaced points of matter and energy.
The final theory presents a state of equilibrium for the universe. If the amount of matter, combined with the force of gravity from that matter, is equal to the force from the Big Bang, then the universe will expand for a time, until it eventually stops expanding completely. However, it will not being to shrink, as stated in the second theory, because the force of gravity has reached a state of equilibrium with the force of the Big Bang.
So what fate do you believe will come to pass?
Some trivial theories exist, such as the existance of "dark matter" and "dark energy," which (if proven true) could drastically effect the fate which will occur. However these two theories are for another discussion, and at another time, for I am thoroughly exhausted from describing all of this. Anyway, I hope you enjoyed it!
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