Hobnobs Posted August 9, 2007 Report Share Posted August 9, 2007 Yeah, but like a lot of physics, there is an awful lot which is extremely hard to comprehend using what we assume to be the normal. Most of the stuff you learn when you are younger has to be thrown out the window when you consider some of the theory's about the universe.One thing that amused me;Imagine two trains traveling towards each other at 100mph, the relative speed of one compared to the other is 200mph. Do the same with two beams of light, and although they are both going at the speed of light, the relative speed is still only the speed of light. Quote Link to comment Share on other sites More sharing options...
ilikeriding Posted August 9, 2007 Report Share Posted August 9, 2007 (edited) I thought the universe was infinite and expanding. Which leads to the impossible question 'What is it expanding into?'.By the way, they know the universe is expanding due to the Hubble equation and Doppler shift. Stars in the distance appear red due to 'red shift' - this indicates that they are moving away from us. It's pretty basic really, no philosophy required.The universe cant expand into anything if it is infinite, as it would already go on forever. Edited August 9, 2007 by afroman Quote Link to comment Share on other sites More sharing options...
Gavyn. Posted August 9, 2007 Report Share Posted August 9, 2007 The universe is everything that exists that we can detect in one huge area. As we can't detect everything how can we say the universe is infinite and it's expanding into nothing? Quote Link to comment Share on other sites More sharing options...
Krisboats Posted August 9, 2007 Report Share Posted August 9, 2007 Imagine two trains traveling towards each other at 100mph, the relative speed of one compared to the other is 200mph. Do the same with two beams of light, and although they are both going at the speed of light, the relative speed is still only the speed of light. Whats complicated about that? Quote Link to comment Share on other sites More sharing options...
Hobnobs Posted August 9, 2007 Report Share Posted August 9, 2007 (edited) Well, they would be traveling at each other at twice the speed, but it isn't? Edited August 9, 2007 by Hobnobs Quote Link to comment Share on other sites More sharing options...
will Posted August 9, 2007 Report Share Posted August 9, 2007 Watch and learn about the universe and string theory Quote Link to comment Share on other sites More sharing options...
Haz Posted August 9, 2007 Report Share Posted August 9, 2007 The universe isn't infinite, it's about 156 billion lightyears wide.Or about 1 000 000 000 000 000 000 000 000 miles wide.In theory, the 'edge' is where no more matter exists.It can expand, because there is nothing there. Quote Link to comment Share on other sites More sharing options...
poopipe Posted August 9, 2007 Report Share Posted August 9, 2007 i like the "it's like a magic balloon way" of explaining it bestI shall explainimagine a magic balloon where your standard 3 dimensions are compressed into the 2 dimensional surface of the balloon, when you inflate the balloon it gets bigger but there's no edges to the 2 dimensional surface - if there's no edges it must be infinite(ish) but it can still expand. get it?if not you're thick Quote Link to comment Share on other sites More sharing options...
RicH_87 Posted August 9, 2007 Report Share Posted August 9, 2007 everyone in this thread is wrong. Quote Link to comment Share on other sites More sharing options...
Has anyone seen my shoe? Posted August 9, 2007 Report Share Posted August 9, 2007 @ richWell, they would be traveling at each other at twice the speed, but it isn't?Nothing can move faster then the speed of light Quote Link to comment Share on other sites More sharing options...
ManxTrialSpaz Posted August 9, 2007 Report Share Posted August 9, 2007 (edited) everyone in this thread is wrong.I concur. There is no universe and you're all a figment of my imagination.Nothing can move faster then the speed of lightYeh, but the relative sped would lightx2 wouldn't it? As nothing is actually travelling faster than light. Edited August 9, 2007 by ManxTrialSpaz Quote Link to comment Share on other sites More sharing options...
Has anyone seen my shoe? Posted August 9, 2007 Report Share Posted August 9, 2007 No! I cant explain it but it doesn't! Quote Link to comment Share on other sites More sharing options...
Tomm Posted August 9, 2007 Report Share Posted August 9, 2007 Imagine two trains traveling towards each other at 100mph, the relative speed of one compared to the other is 200mph. Do the same with two beams of light, and although they are both going at the speed of light, the relative speed is still only the speed of light.I don't follow that at all - I think you're missing a crucial part of the argument?My polo can travel at 120mph, no faster. It it impossible for it to go faster (in the same way light cannot go faster than its max speed). An identical polo comes in the opposite direction. Both cars are doing 120mph. As they pass the relative speed is 240mph. The universe cant expand into anything if it is infinite, as it would already go on forever.It's a paradox, it's not something that can easily be explained. Quote Link to comment Share on other sites More sharing options...
george_seamons Posted August 9, 2007 Report Share Posted August 9, 2007 My polo can travel at 120mph, no faster. It it impossible for it to go faster (in the same way light cannot go faster than its max speed). An identical polo comes in the opposite direction. Both cars are doing 120mph. As they pass the relative speed is 240mph.Surely at the precise moment they pass, they are doing 0mph?Probably just me being stupid, and thinking the wrong way, but wouldn't it, in essence be 120-120?...actually, thinking about it, I guess its 120+-120 (thinking about it on a number line kind of idea, so the + and - form to make a + ? Quote Link to comment Share on other sites More sharing options...
Has anyone seen my shoe? Posted August 9, 2007 Report Share Posted August 9, 2007 (edited) Your third sentance is right, its 120 +- 120 Edited August 9, 2007 by Has anyone seen my shoe? Quote Link to comment Share on other sites More sharing options...
downhill_rob2@hotmail.com Posted August 9, 2007 Report Share Posted August 9, 2007 (edited) I seen somewhere on the internet about a website about the sun's ect...And it shows a picture in comparison in the sizes of them all, and ours is one of the smallest sun's, on your computer screen, you couldnt see it (no pixel small enough) and the biggest couldnt actually fit on the screen scarey.http://www.samtsai.com/pix/yadayada/p318a.jpghttp://www.samtsai.com/pix/yadayada/p318b.jpghttp://www.samtsai.com/pix/yadayada/p318c.jpghttp://www.samtsai.com/pix/yadayada/p318d.jpghttp://www.samtsai.com/pix/yadayada/p318e.jpg Edited August 9, 2007 by terror-error Quote Link to comment Share on other sites More sharing options...
1a2bcio8 Posted August 9, 2007 Report Share Posted August 9, 2007 (edited) I was asked by a colleague, what would happen if you went to the edge of the universe?How do scientists know where the edge is and what is beyond?To think of the universe as having an edge is probably, in my estimation, a problem of semantics or words. The word we use to describe the universe has certain qualities and we tend to mix them up with the thing that the word describes. Therefore, because a word contains a boundary, or 'edge' we think that the ineffable thing it describes also has a boundary or edge.Not that I know if the universe has an edge, this just seems worth considering, to my mind, before you ask the aforementioned question.Regarding space expanding, depending on what you mean, I can see a potential flaw in claiming such knowledge. If you are measuring space (as in matter-less or measurable-less area), you could only possible know if it were expanding if there was some measurable quality opposing it, at it's end. You can only measure something that is not there when it is contrasted with something that is there, regarding the perception of some measuring device (including the human nervous system). So if they do know that 'space', as I define it, is expanding then I guess there must be an edge that science knows about? As far as I'm aware, science doesn't know of something measurable at the end of space? I'm thinking that some of you are actually describing measurable matter, such as planets and stars, as something which is expanding. I see this as making sense and being testable at this point in time. I think however that this misses the initial question. Unless I've ballsed up my understanding Edited August 9, 2007 by rowly Quote Link to comment Share on other sites More sharing options...
Concussion Posted August 9, 2007 Report Share Posted August 9, 2007 I seen somewhere on the internet about a website about the sun's ect...And it shows a picture in comparison in the sizes of them all, and ours is one of the smallest sun's, on your computer screen, you couldnt see it (no pixel small enough) and the biggest couldnt actually fit on the screen scarey.http://www.samtsai.com/pix/yadayada/p318a.jpghttp://www.samtsai.com/pix/yadayada/p318b.jpghttp://www.samtsai.com/pix/yadayada/p318c.jpghttp://www.samtsai.com/pix/yadayada/p318d.jpghttp://www.samtsai.com/pix/yadayada/p318e.jpgMy god, I knew how big the sun was compared to us... jesus I feel small! Quote Link to comment Share on other sites More sharing options...
Joel Posted August 9, 2007 Report Share Posted August 9, 2007 (edited) My head hurts.EDIT: Stupid spelling mistake >.< Edited August 10, 2007 by Joelio Quote Link to comment Share on other sites More sharing options...
Dani. Posted August 9, 2007 Report Share Posted August 9, 2007 (edited) Yeah, rowly is right, fact. There is no way to quantify or measure something without there being a contrast with another "known" or quantified thing which is in turn measured/quantified with an imaginary known (a metre for example). Er..about the polo going 120+mph, I don't see how that compares to light and the speed of light and light's max speed. Light travels at the fastest speed known to man. That speed, incidently, has been proven to be the "ultimate" speed...after that your mass becomes infinite and god knows what happens (E=MC^2 bitches), ever heard of something going faster than the speed of light other than in star wars? or anything else that travels the speed of light for that matter? Thought not. I Have seen the proven facts, I personaly didn't understand all of it but I'll take Einstein's word for it . It has been agreed among the boffins of physics that a photon (light when under a particle form for the younger of you) has no mass. "Why, in that case, can a photon move an atom during the process of laser cooling then?" I hear you ask (or not) - In that case Radiation pressure plays a part but thats damn complicated.Yeah so as someone said, after a certain point in physics everything you know as being true suddenly isn't and there'e an obscure and absurd explanation for everything. Im sure that even the likes of Stephen hawking will admit that much of what they know about our universe is merely based on educated guesses. Edited August 9, 2007 by Dani. Quote Link to comment Share on other sites More sharing options...
ilikeriding Posted August 9, 2007 Report Share Posted August 9, 2007 It's a paradox, it's not something that can easily be explained.please do Quote Link to comment Share on other sites More sharing options...
poopipe Posted August 9, 2007 Report Share Posted August 9, 2007 please doi refer you to my magic balloon explanation Quote Link to comment Share on other sites More sharing options...
ilikeriding Posted August 9, 2007 Report Share Posted August 9, 2007 i refer you to my magic balloon explanationNot quite following the bit where the universe is actually 3 dimensions compressed into 2 Quote Link to comment Share on other sites More sharing options...
Tomm Posted August 9, 2007 Report Share Posted August 9, 2007 Er..about the polo going 120+mph, I don't see how that compares to light and the speed of light and light's max speed. Light travels at the fastest speed known to man. That speed, incidently, has been proven to be the "ultimate" speed...after that your mass becomes infinite and god knows what happens (E=MC^2 bitches), ever heard of something going faster than the speed of light other than in star wars? or anything else that travels the speed of light for that matter? Thought not.Yeah yeah I know all that, but we're not talking about anything travelling faster than the speed of light. We're just talking about one photon's speed relative to the other one. This doesn't require anything to actually travel at the speed, which is why I don't see the problem and I'm sure the question is just worded slightly wrong.P.S. If a plane was on a giant treadmill and the speed of the treadmill matched the speed of the plane's wheels... Not quite following the bit where the universe is actually 3 dimensions compressed into 2No, he's not saying that. He's saying you should imagine it as a 2 dimensional structure, and that's the sort of idea. But in our universe it's actually in 4 dimensions. When you start trying to imagine stuff in greater than 3D, it becomes VERY hard, I certainly can't do it. The balloon analogy just simplifies it to a point we can understand. Quote Link to comment Share on other sites More sharing options...
ManxTrialSpaz Posted August 9, 2007 Report Share Posted August 9, 2007 P.S. If a plane was on a giant treadmill and the speed of the treadmill matched the speed of the plane's wheels... It takes off goddamnit! Quote Link to comment Share on other sites More sharing options...
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