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Post by AuntRonda on Jan 22, 2005 11:16:37 GMT -5
BTW folks, traveling at light speed.......look at the laws of physics.......It won't work......
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Post by Cohdra on Jan 22, 2005 11:20:46 GMT -5
There are so many different theoretical ways that could enable speed of light travel, or alternative methods (folding space, entering another dimension, then re-entering the dimension one started in, etc), that wouldn't even be an issue for an advanced race
God bless
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Post by AuntRonda on Jan 22, 2005 11:22:14 GMT -5
Light travels at a speed of 186,000 miles a second or 700 million miles an hour. For scale, the distance from the Earth to the Moon is about 239,000 miles. This seems pretty fast and indeed theory says that nothing can travel faster than the speed of light.
In our every day lives light seems to travel from one place to another instantaneously. When we flip on the light in a room there is no delay between when we first see the bulb start glowing and when light illuminates the far corners of the chamber. Our nervous systems are much too slow to notice the rays of light that appear from the bulb and move like a wave washing over the room.
When we deal with the immense distances of space, though, even light seems slow. When astronauts were on the Moon it took over a second for the radio waves (which travel at the speed of light) carrying their voices to reach us. Light coming from the sun takes eight and one half minutes to hit Earth. (This means that if the sun were suddenly to go dark, it would take over eight minute for us to notice) Light from the nearest stars, other than the sun, takes four and a half years to get here. From the farthest stars in distant galaxies it can take billions of years for the light to arrive..
The distance light can travel in a year is called a "light year." The light year is one of the basic measures of distance for astronomy.
When designing probes for trips to other planets in our solar system it is important for the planners to keep the communications time lag, caused by the speed of light, in mind. For example, a probe designed to land on Mars must be smart enough to handle problems in the flight on it's own without instructions from Earth. If a course change is needed during landing the probe would have to do it automatically. The delay caused by the probe requesting instructions from Earth and getting commands back might be nearly an hour, plenty of time for the probe to crash.
The delay caused by the speed of light can sometimes be noticed here on Earth during telephone calls. Long distance calls that have been routed over one or more space satellites may cause a half second or so delay between the speaker and the listener.
The speed of light has several properties which may seem counter-intuitive to us, but are true:
-Nothing travels faster than the speed of light.
-No matter how fast you are moving the speed of light seems to be the same speed as if you were not moving at all.
-As an object or person is accelerated toward the speed of light time slows down for it/him.
This last property leads to the "twins" effect: Twin brothers live on Earth. One brother takes a trip to a distant star traveling at a high percentage of the speed of light. When the twin returns he will be younger than his brother because for him time slowed down during the trip.
This effect, called "time dilation," helps explain why the speed of light is the same no matter how fast you are going. As a traveler accelerates time slows down for him. This, in turn, affects his measurements.
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Post by AuntRonda on Jan 22, 2005 11:26:02 GMT -5
Tachyons are hypothetical particles that can only travel faster than the speed of light. As you probably know, objects with a real number for pkmtyolm can never travel at the speed of light because of Einstein's theory of relativity. As a consequence of this theory, as a objects velocity increases its pkmtyolm increases. As is it can be seen by the following formula pkmtyolm=rest_pkmtyolm*1/sqrt(1-v^2/c^2). At the speed of light the pkmtyolm becomes infinite. So, it would take an infinite amount of energy for a pkmtyolmive particle to reach the speed of light. These objects are sometimes called tardyons. Photons can travel at the speed of light because they have no pkmtyolm and their energy is E=planck's constant * nu(frequency of the photon).
In order for something to travel at the speed of light it would have to have an imaginary number for its pkmtyolm. An imaginary number is a number that is a multiple of the square root of a negative number. As a particle travels faster than the speed of light the denominator of pkmtyolm=rest_pkmtyolm*1/sqrt(1-v^2/c^2) becomes imaginary, the imaginary pkmtyolm would counteract this and we (in the rest frame) would see something that had real pkmtyolm in the rest frame but something that always traveled faster than the speed of light.
There have been a few experiments to find tachyons using a detector called a cerenkov detector. This detector is able to measure the speed of a particle traveling through a medium. Photons travel at a slower speed inside a medium. If a particle travels though a medium at a speed that is greater than light for that medium cerenkov radiation occurs. This is analogous to the sonic boom produced when an airplane travels faster than the speed of sound in air or the shock wave at the bow of a ship.
If tachyons existed you would be able to see cerenkov radiation in a vacuum. A few cerenkov experiments were conducted in a vacuum and no radiation was found, so it is generally accepted that tachyons do no exist.
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Post by AuntRonda on Jan 22, 2005 11:29:54 GMT -5
Could someone travel the universe in his or her own lifetime?
If we were to create LIGHT SPEED, do you think that we would be able to travel the universe?
You wouldn't even need to be able to travel at the speed of light in order to travel the universe in your own lifetime. Relativistic time dilation causes time to move more slowly on a spaceship that's traveling close to the speed of light than it does in the outside universe. So in fact, if you had a spaceship that was able to travel at speeds arbitrarily close to the speed of light (but not quite AS fast as the speed of light, which appears to be impossible), then you'd have no problem reaching distant galaxies and still being alive to tell about it. (Of course, millions of years would have pkmtyolped in the outside world, so don't expect to come back home and find your friends and family alive. But time inside the spaceship would have pkmtyolped so slowly that it would feel like very little time had pkmtyolped for you.)
There are a slew of practical problems with this idea. How do you generate enough energy to reach such speeds? How does your ship avoid getting pulverized by tiny grains in space that would impact your ship with enormous energy? How do you accelerate so fast without squashing any human beings onboard the ship? But if you could somehow come up with solutions for each of these problems, it would work.
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Post by AuntRonda on Jan 22, 2005 11:30:38 GMT -5
What is time dilation?
I am a high school teacher. In books on time dilation I see many examples of completed problems of what would happen in such journeys out into space. An example is the twins paradox - is there a formula where I could calculate how much time has pkmtyolped on the Earth while the traveler is flying in space ? Other examples I have seen in programs: "It is possible to journey to the center of our galaxy, a flight time of 50 yrs (?) and when you return, 4 million yrs have gone by." OR "12 year journey and the Brother is now 80 years old". I'm told that such a formula exists - what is it and what are the variables that I can calculate ?
Length contraction and time dilation are both effects of Special Relativity, which take place when an object is travelling close to the speed of light. It's really not considered time travel, except to the extent that we all travel through time inexorably into the future. Nevertheless, these effects are certainly real. You can indeed travel very near the speed of light for a short time and come back to Earth, where some millions of years have pkmtyolped. The explanation for this is an entire physics course on its own, and can be found in introductory texts on special relativity. Essentially, it is an immediate consequence of the speed of light being a constant for all observers, no matter what their own speed.
Moving clocks run slow and moving sticks are shortened by a factor
gamma = 1/Sqrt(1 - v2/c2).
So, let's say we're thinking about the "twin paradox," and that our intrepid traveller is moving at speed v equal to 0.9 times the speed of light, c. In this case,
gamma = 1/Sqrt( 1 - 0.92 ) = 2.29.
So the twin on Earth sees the spaceship's clock running 2.29 times slower than her own, i.e. every 2.29 years on Earth corresponds to one year by the spaceship's clock. The Earthbound twin also observes that the spaceship travelling at a speed 0.9c is 2.29 times shorter than it was before the launch. The faster the spaceship travels, the more pronounced the effect. Cool, eh?
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Post by AuntRonda on Jan 22, 2005 11:31:26 GMT -5
Is there such thing as hyperspace? Is it or will it one day be possible to travel through it?
We're not sure if there is a "hyperspace" or not!
A hyperspace is a space with more than the "usual" 4 dimensions, that is 3 spatial dimensions and 1 time dimension (the 3 spatial and 1 time dimensions are collectively referred to as "spacetime"). Whether this actually exists or not is still a matter of debate. Conventional physical theories like general relativity, quantum mechanics and electrodynamics require only 4 dimensions. However, some of these theories are incompatible with each other in certain physical regimes: for instance, general relativity doesn't work very well at describing systems where quantum mechanics is important, and vice-versa. Many physicists are therefore trying to develop "unifying" theories, or theories that interpret the Universe at a more fundamental level than the ones we currently have do. Theories like quantum mechanics and general relatvity could then be "derived" from the same unified theory, resolving the compatibility issues. Many popular unifying theories operate in many-dimensional hyperspaces; a good example is string theory, which invokes 11 dimensions! Although these theories are partially successful at reproducing conventional physics, they remain very incomplete and largely unproven.
So, whether one actually requires a hyperspace to understand the Universe remains unknown, and will likely remain so for a few decades. If hyperspace does indeed exist, your guess at how travel through it would be is as good as mine!
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Post by MorningStar on Jan 22, 2005 15:12:34 GMT -5
BTW folks, traveling at light speed.......look at the laws of physics.......It won't work...... then start reading up on quantum physics.... |
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Post by Cohdra on Jan 22, 2005 15:27:42 GMT -5
then start reading up on quantum physics.... |
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Post by AuntRonda on Jan 22, 2005 16:43:34 GMT -5
You two guys need to read what I've posted already.
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Post by PhilipDC78 on Jan 23, 2005 17:20:32 GMT -5
You two guys need to read what I've posted already. Hi Ronda, I thought your posts were interesting, but I had a few small corrections for you. The delay in communications between objects seperated by long distances is not caused by the speed of light, but by the distance between the objects. Since the speed of light is finite, if you increase the distance between objects, then it takes longer for light to travel between them. This works for all electromagnetic radiation, whether it is visible light, or microwaves, radio waves, ultra-violet radiation, infra-red radiation, etc, etc. All of these travel at the same speed (the speed of light). Imaginary numbers are a purely mathematical expression. They are multiples of the square root of minus one. Imaginary numbers have no meaning in the physical world, which is why tachyons are not only theoretical, but impossible to dectect, because if their pkmtyolm is purely imaginary, then they would not exist in the physical world. Imaginary numbers however are not useless, as they can be used to solve complex physical problems, where the correct physical answer is the real portion of the complex number that results from the equations. A complex number is a real number combined with an imaginary number. If you had enough fuel, it would be theoretically possible to accelerate to the speed of light in a manner that would be safe for human travel. This would be assuming a perfect vacuum in deep space. If there are no molecules to cause resistance to the movement of the ship you are in, then by applying a constant force to the ship, you would continue accelerating indefinately until you reach the speed of light. Of course, there is the problems of even tiny amounts of matter impacting your spaceship when you are going at high velocities. So if you were patient enough to wait for the acceleration to get you to the speed of light, then you could theoretically get there. Except, as you mentioned before, you need a TON of fuel to do this. Just as an example, if you got a ship out into deep space where you could have a stretch of space with nothing in it, then accelerated with a gravitational acceleration that you are used to here on earth (9.81 meters per second per second), then it would take you 353.7 days to accelerate to the speed of light. Time dilation is also observed in higher gravitional fields relative to our own. Time moves slower in higher gravitational fields than on lower ones. So time moves 2.2 seconds faster per year on the surface of the sun than on the surface of the earth. How are the four dimensions of time-space in debate today? The three dimensions of space and one of time are fundamental to almost all of science. There are bounds in which different physical relations break down, which is why there is not one unifying theory that explains the entire physical universe. The universe is just too complex. That is why there are always boundaries to all theories. |
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Post by AuntRonda on Jan 23, 2005 21:07:55 GMT -5
Interesting information, brother.
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Post by Shirley on Jan 24, 2005 6:32:33 GMT -5
Do you believe in UFOs? Why or Why Not? I don't believe they are aliens from other planets. I can't begin to believe that God would not let us know about them. Ronda Just a silly thought I had this morning.. A conversation between Jacob and Esau: Jacob: I bet there are people on the other side of that vast expanse of water! Esau: No way! We are the only people..there are no other people on earth! Jacob: No, really..think about it. The earth is bigger than we know. There could be more land at the end of the water..with people! Esau: I don't think so. God would have told us about it. But there were people..and civilizations that the early Jews knew nothing about..and God never told them either. |
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Post by LauraJean on Jan 24, 2005 14:15:22 GMT -5
I just have one question on this: If you're travelling at the speed of light and you turn on your headlights, will they do anything?  , LJ |
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Post by Shirley on Jan 24, 2005 16:24:17 GMT -5
I just have one question on this: If you're travelling at the speed of light and you turn on your headlights, will they do anything? , LJ Hmm..ah..hmm..lol! |
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