The argument that scientists have for there not being a center of the universe is that galaxies will reeceed away from you no matter where your located in the universe. How do they know that if they never been to another galaxy?
They don’t. However, they hold very dearly to the principle of relativity, that the laws of physics are the same in all inertial reference frames and have the same form in all reference frames in general. In brief, this means that there are no "special" places from which to view the Universe. It is difficult to know if this is really so, given the impossibility of going significantly "elsewhere". One can, however, make measurements such as the atomic or molecular spectroscopic features imprinted on light from distant stars that passes through intervening clouds of dust and gas or the features caused by trace elements in a distant star itself. These data can be explained by the same physics we see at work here on Earth.
February 14th, 2010 at 11:19 pm
it’s not just about galaxies but about everything, the universe is constantly expanding and moving apart, so everything recedes.
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February 14th, 2010 at 11:37 pm
By observing something called the doppler effect. By observing the light spectrum of objects they can tell if an object is approaching us or receding away from us. Light from the observed spectrum will be red shifted toward longer wavelenghts, and approaching objects will be blue shifted towards shorter wavelenghts. If you have ever heard an approaching train, you have observed the doppler effect. As the train approaches you it’s horn sounds higher pitched and as that train moves away from you, its horn is lower in pitch,
References :
http://www.britannica.com/EBchecked/topic/494505/red-shift
February 15th, 2010 at 12:12 am
Basically imagine a rubber band strand, and draw some dots on it with a pen or marker. Each of those represent a planet. Then center one of the dots and focus on that one, and pull the two ends stretching it. All the other dots will appear to be moving away from the dot you have in the middle, with the furthest ones moving the fastest. But if you were to put a different dot in the middle, it would appear all others are moving while that one stays still. The fact is that SPACE itself is expanding not just objects are moving around. Its expanding in all directions constantly, so the idea of a middle point really doesn’t work out. No matter what planet you are on, from that perspective it will appear that everything else is mostly moving away from you. Another example you can do for yourself is drawing dots on a balloon then inflating it up and watching them spread apart.
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Carl Sagan video I watched a while back, tried looking for it but couldn’t find it. Any videos of him on youtube would probably interest you if you like this kinda stuff though.
February 15th, 2010 at 12:39 am
If our galaxy( Milky-way) the size of earth then our solar-system would be the size of a grain of sand if not smaller… we do not have equation of motion for celestial mechanical-problem to know at any giving moments as to where a planet would be or was in the future or the past.only by numerical-configeration (super-computer) within a window of 32.7 days. this is howmuch diffecalty they have( scientists) in our grain of sand (solar-system) and yet they speak of the doppler effect ( The train is going away from us) it must be the mid-nite train to Georgia,and if it’s coming toward us then it must be the soooooooooul traaaaain. and just rememer it take a minimum of (5–10) million yrs for a galaxy to make a ful rotation a roud the super black-hole( from the big-bang) and it takes Pluto 248 yrs. to rotate once around the sun so please wake me up when Pluto reaches the end.so I could catch the mid-nite train to Georgia cause it’s on my mind Georgia…oh you could call me charles…
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February 15th, 2010 at 12:51 am
First, not all galaxies will recede from you; there are clusters, and even super-clusters, containing galaxies that hang together and even approach each other. However, these super-clusters are receding from one another, so the general argument still holds.
Second of all, although it is true that objects receding from you will red-shift according to the Doppler Effect, and the argument for the expansion of the universe does depend on observations of red-shifting, this latter red-shifting is not due to the Doppler Effect, even though many popular articles spread this misconception, and even some of the physicists thought it was a Doppler effect soon after the red-shift was discovered. It is a similar phenomenon, which is why understanding the Doppler Effect would be one step to understanding this phenomenon. The other phenomenon is a bit more complex, and so the simplification to the Doppler Effect is the easy way out. Red-shifting is the changing of the color of the light reaching your eyes towards less energetic light; in the visible spectrum, this means shifting towards the red end of the spectrum. The Doppler Effect does this essentially by stretching out the wavelength of the emitted light via the relative velocities of the emitter and the observer. However, the universe’s expansion is due to the constant changing of the geometry of space, sometimes called the stretching of the fabric of space. You can think of the substrate of space being stretched, and this also stretches light that goes through it, light a spring attached to a rubber sheet that is being stretched. It is a bit of a jump, as you are used to thinking of the vacuum as "nothing", but it really is something that can change its structure.
You might say: what’s the difference? To see the difference between the Doppler effect and the expansion of the fabric of space, note that light goes at a constant speed with respect to this fabric of space. Imagine this experiment: you shine a light out into space, and after a year, someone asks you how far away the light is. You would say one light-year, of course. But it would actually be further away from you, because it had been "carried along" on the substrate. It is a bit like you running on an escalator in the same direction as the escalator. This sort of thing affects the estimated distances that galaxies are away from us, and the way their incoming light is interpreted.
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February 15th, 2010 at 12:56 am
They don’t. However, they hold very dearly to the principle of relativity, that the laws of physics are the same in all inertial reference frames and have the same form in all reference frames in general. In brief, this means that there are no "special" places from which to view the Universe. It is difficult to know if this is really so, given the impossibility of going significantly "elsewhere". One can, however, make measurements such as the atomic or molecular spectroscopic features imprinted on light from distant stars that passes through intervening clouds of dust and gas or the features caused by trace elements in a distant star itself. These data can be explained by the same physics we see at work here on Earth.
References :