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Post by theartak on Jan 23, 2005 20:03:14 GMT -5
I'm curious if anyone has any information about this.
It's pretty much a given that space has no atmosphere to speak of. Countless tests have verified this.
I'm just curious when we established that as a fact? I mean, was that known before we began our forays into space, or what?
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ConqueringWolf
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Post by ConqueringWolf on Jan 23, 2005 20:29:34 GMT -5
I think well before our space travel.....the only thing i could find to support that idea is this clipping of an article talking about the vacuum of space...
True, the cosmos consists overwhelmingly of vacuum. Yet vacuum itself is proving not to be empty at all. It is much more complex than most people would guess. "But surely," you might ask, "if you take a container and remove everything from inside it - every atom, every photon - there will be nothing left?" Not by a long shot. Since the 1920s physicists have recognized that on a microscopic scale, the vacuum itself is alive with activity. Moreover, this network of activity may extend right down to include the very structure of space-time itself. The fine structure of the vacuum may ultimately hold the keys to some of the deepest questions facing physics - from why elementary particles have the properties they do, to the cause of the Big Bang and the likelihood of other universes outside our own.
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xkamelx
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Post by xkamelx on Jan 24, 2005 8:27:51 GMT -5
I would say Wolf's answer is correct. Space isn't empty, and it isn't a void. It's just that, space, with 0 pressure. That is why in the moves if an airlock is opened, it sucks everything out into space, because the pressure in the space ship is far greater then the pressure of space.
The same as an airplane.
The only thing I disagree with Wolf, is your answer hinted toward more then one universe, which is an oxymoron.
For one; "Uni" means 1(one)
For two, our universe is infinite. There is no end to it, it's impossible according to the laws of physics, and astrophysics.
However, the author may have been talking about our cluster of galaxies caused from or big bang. He may be calling that the universe. Or perhaps he was speaking of the supposed 11 dimensions of space, which would all other universes to be curled into our own.
Either way, the universe is infinite
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ConqueringWolf
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Post by ConqueringWolf on Jan 24, 2005 10:20:49 GMT -5
I think once you start talking about alternate realities and parallel dimensions that you CAN start talking about more than one universe though.....if something exists outside of our realm of space and time and we cant see it and we can't access it....why should we consider it part of "our" universe. I would consider theirs to be a seperate universe unto their own since they occupy different realities.
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Post by theartak on Jan 24, 2005 14:35:44 GMT -5
*runs into middle of discussion*
Yeah that's great guys, but I was talking strictly about lack of an atmosphere...not this whole vaccuum/astrophysical reality stuff. I never said space was empty...just that it didn't have an atmosphere...that's all I'm curious about...and all Wolf's thing established was that we knew there was no atmosphere in the twenties...doesn't explain the origin of the theory.
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ConqueringWolf
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Post by ConqueringWolf on Jan 25, 2005 11:41:43 GMT -5
LOL..yea...it drfited off the main topic shortly there...I couldn;t find any info as to the origin of the theory....just that it was definitely around before space travel as a known fact...
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syborg
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Post by syborg on Apr 20, 2005 11:04:33 GMT -5
Why does light have speed limit? What is stopping it from going any faster?
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Post by timewarp on Apr 20, 2005 16:04:00 GMT -5
Why does light have speed limit? What is stopping it from going any faster? It doesn't have a speed limit. No matter how fast you go, light will always travel away from you at the speed of light.
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Post by Bob Brown on May 3, 2005 0:19:16 GMT -5
Yes that is probally true. But what I think he is asking is why will it stop at a specific speed.
Since I dont know how fast light travles, just for grins, I will say it travles at 1 million mph.
Why does it go 1 million mph and stop? Why dosnt it keep going to 2 million mph and so on?
What you were saying is that if you are already traveling at 1 million mph, and you shine a light infront of you, that light will go another 1 million mph to make 2 million mph. (you with me?)
Why does it go to 2 million and stop? Why not 3 million?
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ConqueringWolf
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Post by ConqueringWolf on May 3, 2005 8:34:11 GMT -5
Yes that is probally true. But what I think he is asking is why will it stop at a specific speed. Since I dont know how fast light travles, just for grins, I will say it travles at 1 million mph. Why does it go 1 million mph and stop? Why dosnt it keep going to 2 million mph and so on? What you were saying is that if you are already traveling at 1 million mph, and you shine a light infront of you, that light will go another 1 million mph to make 2 million mph. (you with me?) Why does it go to 2 million and stop? Why not 3 million? Actually....the speed of light is faster than that...a better comparison would be if you were travelling at the speed of light....and then shined a light in front of you...the light in front of you would not double speed....the speed of light is a constant....light is a set of particles....the energy given off by those particles only allows that energy to travel at a set speed....they cant go faster because it's physically impossible....that woul be like asking why a man cant run at 100 mph.,...because its just physically impossible....the same with light...it is impossible for a light particle to travel faster than the speed it already does. Anyways..if you shined a light in front of you while travelling at the speed of light.....you would never see the light....because you and the light would be traveling at the same speed....so it would never get far enough out in front of you for you to be able to see it....it would be stiuck in the light source you were using.
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Post by timewarp on May 3, 2005 13:20:30 GMT -5
Actually....the speed of light is faster than that...a better comparison would be if you were travelling at the speed of light....and then shined a light in front of you...the light in front of you would not double speed....the speed of light is a constant....light is a set of particles....the energy given off by those particles only allows that energy to travel at a set speed....they cant go faster because it's physically impossible....that woul be like asking why a man cant run at 100 mph.,...because its just physically impossible....the same with light...it is impossible for a light particle to travel faster than the speed it already does. Anyways..if you shined a light in front of you while travelling at the speed of light.....you would never see the light....because you and the light would be traveling at the same speed....so it would never get far enough out in front of you for you to be able to see it....it would be stiuck in the light source you were using. That is incorrect. Light is not matter, it doesn't move the same way. Light is a form of energy. A wavelength. People get mixed up about this. The speed at which light travels away from you is a constant. The actual speed of light depends entirely on your speed.
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oblivion
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Post by oblivion on May 3, 2005 13:57:56 GMT -5
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syborg
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Post by syborg on Jun 13, 2005 10:08:40 GMT -5
Sorry I just do not understand the article
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Moreta
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Post by Moreta on Jun 13, 2005 11:19:37 GMT -5
Im going to do my best to explain everything I know about light etc in as simple terms as possible since there seems to be a lot of confusion in this thread
In a vacuum light travels at 3x108m/s (ie. 300 000 000 metres per second or 300 million metres per second). This speed is also in fact the universal speed limit. It is not physically possible for anything to travel faster than this speed. This is because as your speed increases, your mass increases and so it takes more energy to make you go faster. As you reach 3x108m/s your mass becomes infinite and so it takes an infinite amount of energy to make you go any faster meaning it is not physically possible to accelerate past the speed of light. (Note here I have said accelerate, it may be that in the future some clever way is found of just going from standing to massive speeds without accelerating, just from changing from one thing to another. But accelerating past it is not physically possible.)
It is also important to note at this point that at these high speeds your experience of time is different to those travelling at slow speeds.
Next we come onto what happens if you were travelling at the speed of light and you shone a light at something. The light would travel away from you still at the speed of light in every direction relative to your motion. which therefore means surely that it is then going faster than 3x108m/s? Well, you see, this is where it begins to hurt your head. You see, to someone who was off to one side and wasnt moving, the light would also travel at 3x108m/s which means it must in fact be travelling at two different speeds at once which obviously cant be possible. The way I understand it is simply that high speeds affects time and this means because time is going faster or slower for you it would make something appear to travel faster or slower.
Next we get onto the complicated talk about light being a particle and being a wave at the same time. This is something that is still not understood by physicists around the world but it is certain, that under the theories we have at the moment that best explain it, light can behave as a particle or a wave. There are experiments that prove each to be true. If youd like me to describe both of them let me know, Id be happy to, its good revision for my Physics A2 anyway
Right that is all I can think of for the moment. Theres probably things I have missed out as well but I certainly hope it helps explain a bit of this confusion
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