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Space, distance, time. ???
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 2014-03-20 10:32 PM |
Elite  6387    |  Subject: Space, distance, time. ???OK, I am usually a big picture guy. Concepts are not usually lost on me... but I have to admit, I don't really get space/time/distance. In fact, I do not get it to the point I'm not sure how to ask an intelligent question to help me figure it out.
So time/distance. I get it. It takes a year for light to go a light year. Duh. Looking out trillions and trillions of miles... is actually looking back in time. And now our telescopes are looking back 13 billion years, to the beginning of our universe..... but it isn't the beginning of the universe...because that happened 13 billion years ago. I understand that what we are seeing is light emitted 13 billion years ago... but we can't see the Big Bang, because we were not here. It already happened. I guess I get confused because distance is put in context of looking back in time... but we can't actually see the past. The light from the Big Bang was emitted 13 billion years ago... us with it... and the universe expanded... for 13 billion years... us with it, and now we are looking back from where we came from... but it isn't the "past".
Is it just me? Am I even making an intelligent question here? Help explain it to this 2 year old.
PS: I'm sure you realize weed is legal here... but I'm not stoned. If I was, I would probably have no problem getting this. At least that's how it used to work for me.
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| 2014-03-21 8:30 AM in reply to: 0 |
Veteran 485 | Subject: RE: Space, distance, time. ??? Originally posted by powerman OK, I am usually a big picture guy. Concepts are not usually lost on me... but I have to admit, I don't really get space/time/distance. In fact, I do not get it to the point I'm not sure how to ask an intelligent question to help me figure it out.
So time/distance. I get it. It takes a year for light to go a light year. Duh. Looking out trillions and trillions of miles... is actually looking back in time. And now our telescopes are looking back 13 billion years, to the beginning of our universe..... but it isn't the beginning of the universe...because that happened 13 billion years ago. I understand that what we are seeing is light emitted 13 billion years ago... but we can't see the Big Bang, because we were not here. It already happened. I guess I get confused because distance is put in context of looking back in time... but we can't actually see the past. The light from the Big Bang was emitted 13 billion years ago... us with it... and the universe expanded... for 13 billion years... us with it, and now we are looking back from where we came from... but it isn't the "past".
Is it just me? Am I even making an intelligent question here? Help explain it to this 2 year old.
PS: I'm sure you realize weed is legal here... but I'm not stoned. If I was, I would probably have no problem getting this. At least that's how it used to work for me.
Hmmm...not stoned either or I would get it too... But, we really aren't looking into the past per se, we are merely looking at light that traveled 13 billion years to get here. But to move through any space no matter where it is, is moving through time. Even sitting still we are still moving through time. Its the relative thing that really churns my butter...the train speeds by and ball is thrown in the air by a passenger, inside the train the ball is moving at what appears to be a regular speed, but to the observer on the platform looking in, the ball is still. Time is relative and so is the space in which we travel. Its why our satellites have to be calibrated (daily?) because their clocks move at a different rate time because gravity is pulling space and thus time and slowing it down. weird. And did you see that just 2 days ago maybe, the ripple effects of the big bang as predicted by Einstein were discovered. Apparently this is huge deal in the astrophysicist world. Any way, I am the opposite of an expert, I just like thinking about the grandiosity and the bigger picture too. perhaps Bill Nye, if he can get off the 777 research could chime in, it might be more helpful. love this stuff... Edited by stilgarnaib 2014-03-21 8:31 AM |
| 2014-03-21 8:49 AM in reply to: powerman |
Champion 9407  Montague Gold Mines, Nova Scotia | Subject: RE: Space, distance, time. ??? I'm not sure I'm 100% on what you are asking but I'll take a stab at it. While we are not looking at the "past," we are looking at light that was emitted in the past so it carries information about conditions when it was emitted and any interactions that it had with energy along the way. So, when we look at the microwave background radiation, what we are seeing is light that was emitted shortly after the big bang (once the universe became transparent) that would have existed across the entire EM spectrum, from radio waves to gamma radiation. However, since the universe was rapidly expanding the wavelengths of light emitted became "stretched" as a result of the expansion of space-time meaning that the radiation was red-shifted with the expansion of the universe which has led to the fact that the light we can see from right after the big bang has long wavelengths (microwaves and longer). Then, as the radiation travelled through space, it would have interacted with any energy source which could scatter it and/or further red-shift the light. Since the universe is not uniform, this is why the microwave background radiation is not uniform and areas where light would have had more interactions would have lower energy (longer wavelength) light while areas with fewer interactions would have higher energy. So while we are observing this radiation in the present, it carries information from the moment that it was emitted, including the big bang itself. Not sure if this helps but hope so, Shane |
| 2014-03-21 10:51 AM in reply to: #4968816 |
Elite 6387 | Subject: RE: Space, distance, time. ??? Mainly it is about the evolution of our capabilities to see further and further into space. Billions of light years... Now approaching as old as our universe. So I understand that I may be taking it wrong, but usually when the subject comes up, they invariably mention looking back to the big bang.... But that isn't what we are looking at. |
| 2014-03-21 11:14 AM in reply to: powerman |
Champion 9407 Montague Gold Mines, Nova Scotia | Subject: RE: Space, distance, time. ??? Originally posted by powerman Mainly it is about the evolution of our capabilities to see further and further into space. Billions of light years... Now approaching as old as our universe. As I understand it, the limit of seeing backwards, at least through the observation of photons, is going to be about 300,000 years after the big bang as this is the point at which the universe became transparent. The BICEP data with the gravitational waves was looking at light from about 400,000 years ago which is as far back as we've seen. One of the things that I've always thought was incredibly interesting is that due to the expansion of the universe, every second our view of the observable universe increases by three light seconds and this rate should increase as the expansion of the universe continues to accelerate. So I understand that I may be taking it wrong, but usually when the subject comes up, they invariably mention looking back to the big bang.... But that isn't what we are looking at. This is true and, as things stand right now, there is no way that we will ever be able to see the big bang since the photons were initially be constantly absorbed and then re-emitted so light doesn't go back that far. However, when we observe things such as the microwave background radiation, we are really observing the effects of the big bang and since the models of the big bang accurately predict the background radiation we observe, then we are gaining valuable insight into something we will never directly observe (like so many parts of physics). Shane |
| 2014-03-21 11:42 AM in reply to: 0 |
Member 5452 NC | Subject: RE: Space, distance, time. ??? I've brought it up here before, but "Why Does E=mc2?" by Brian Cox is an interesting, relatively elementary discussion of space-time. Edited by Goosedog 2014-03-21 11:43 AM |
| 2014-03-21 11:42 AM in reply to: gsmacleod |
Sensei Sin City | Subject: RE: Space, distance, time. ??? I have been meaning to read the Universe in a Nutshell - got it on my shelf but only looked at the pictures! Other cool concepts, or ways to think of it. If you look at a clock across the room and it strikes 2pm, you are only seeing the light/image of the clock when it hit 2pm just a FRACTION of time after it really hit 2pm due to the time it takes the light/image to reach you from the clock. Now say you are moving away from the clock at some speed. It will take longer for the image to get to your eye so time will appear to slow down. As you approach the speed of light, time will actually appear to stop. If I recall from days of physics in college and my armchair physics, this lead to the theory that if you travel at the speed of light, you basically don't age compared to people that don't (I believe Einstein came up with that). I also believe there were tests done to prove it. Clocks that were synced up on earth, one went into space and was traveling VERY fast (of course nowhere near the speed of light) came back and they found the space clock was behind the earth clock - basically time slowed for the faster moving clock... OR, I could be totally wrong.
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| 2014-03-21 12:07 PM in reply to: Kido |
Champion 9407 Montague Gold Mines, Nova Scotia | Subject: RE: Space, distance, time. ??? Originally posted by Kido I have been meaning to read the Universe in a Nutshell - got it on my shelf but only looked at the pictures! Other cool concepts, or ways to think of it. If you look at a clock across the room and it strikes 2pm, you are only seeing the light/image of the clock when it hit 2pm just a FRACTION of time after it really hit 2pm due to the time it takes the light/image to reach you from the clock. Now say you are moving away from the clock at some speed. It will take longer for the image to get to your eye so time will appear to slow down. As you approach the speed of light, time will actually appear to stop. If I recall from days of physics in college and my armchair physics, this lead to the theory that if you travel at the speed of light, you basically don't age compared to people that don't (I believe Einstein came up with that). This is all the basis of special relativity (ignoring the acceleration in order to make an object speed up or slow down). This is one of the elements that led us to understand that massless particles can travel at the speed of light but particles with masses can only approach the speed of light. It is also why we know that neutrinos must have a mass because they change with time and if they were massless, they would always be the same. An interesting musical science video that: http://www.youtube.com/watch?v=dBxcC8zV46E I also believe there were tests done to prove it. Clocks that were synced up on earth, one went into space and was traveling VERY fast (of course nowhere near the speed of light) came back and they found the space clock was behind the earth clock - basically time slowed for the faster moving clock... The initial test of special relativity involved atomic clocks and jet aircraft - they synched up some atomic clocks, flew one east around the earth and the other west and then compared the clocks and found they were out of synch by an amount predicted by both special relativity and general relativity. We have also observed the combined effects of special and general relativity with the atomic clocks onboard satellites (very important with GPS sats) where the clocks on the satellites will run slower than clocks on earth due to SR but faster than clocks on earth due to the decreased gravitational field with the net result being clocks running slightly fast at orbit. If uncorrected, GPS satellites would be off by about 10km/day so the atomic clocks on these satellites are set to run slow on earth but "correctly" at orbit. http://www.youtube.com/watch?v=ky4RgRvVDoA Shane |
| 2014-03-21 12:16 PM in reply to: Kido |
Veteran 869 Stevens Point, Wisconsin | Subject: RE: Space, distance, time. ??? Originally posted by Kido I have been meaning to read the Universe in a Nutshell - got it on my shelf but only looked at the pictures! Other cool concepts, or ways to think of it. If you look at a clock across the room and it strikes 2pm, you are only seeing the light/image of the clock when it hit 2pm just a FRACTION of time after it really hit 2pm due to the time it takes the light/image to reach you from the clock. Now say you are moving away from the clock at some speed. It will take longer for the image to get to your eye so time will appear to slow down. As you approach the speed of light, time will actually appear to stop. If I recall from days of physics in college and my armchair physics, this lead to the theory that if you travel at the speed of light, you basically don't age compared to people that don't (I believe Einstein came up with that). I also believe there were tests done to prove it. Clocks that were synced up on earth, one went into space and was traveling VERY fast (of course nowhere near the speed of light) came back and they found the space clock was behind the earth clock - basically time slowed for the faster moving clock... OR, I could be totally wrong.
I know you're right about the satellites having different times on earth. It's actually quite common in GPS satellites. To get the accuracy that we need they have to account for the time differential. It is about 4x10-5 seconds each day if I remember correctly. This only equates to 0.0146 seconds in a whole year. Not much, but when your making precise calculations it's enough! Another cool tidbit about the speed of light is how it is a finite speed. Nothing can go faster (leaving out warp theory and other bending of the fabric of space time of course!) take this for example; You throw a tennis ball from a platform moving at 10m/s, you throw the tennis ball at 25m/s. The velocity of the ball at the moment you throw it is 35m/s. Now lets say you turn on a flashlight on the same platform. The speed of light is 299792458m/s, the beam of light does not travel at 299792468m/s it still moves at 299792458m/s.
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| 2014-03-21 12:22 PM in reply to: Justin86 |
Champion 9407 Montague Gold Mines, Nova Scotia | Subject: RE: Space, distance, time. ??? Originally posted by Justin86 You throw a tennis ball from a platform moving at 10m/s, you throw the tennis ball at 25m/s. The velocity of the ball at the moment you throw it is 35m/s. Now lets say you turn on a flashlight on the same platform. The speed of light is 299792458m/s, the beam of light does not travel at 299792468m/s it still moves at 299792458m/s. And what is really cool is that everybody in the universe, regardless of their relative motion, would measure the speed of light to be the same! This leads to some fun, seemingly paradoxical problems that are used to frustrate, I mean enlighten, those who are just being introduced to SR. Shane |
| 2014-03-21 5:10 PM in reply to: gsmacleod |
Elite 6387 | Subject: RE: Space, distance, time. ??? Originally posted by gsmacleod Originally posted by Justin86 You throw a tennis ball from a platform moving at 10m/s, you throw the tennis ball at 25m/s. The velocity of the ball at the moment you throw it is 35m/s. Now lets say you turn on a flashlight on the same platform. The speed of light is 299792458m/s, the beam of light does not travel at 299792468m/s it still moves at 299792458m/s. And what is really cool is that everybody in the universe, regardless of their relative motion, would measure the speed of light to be the same! This leads to some fun, seemingly paradoxical problems that are used to frustrate, I mean enlighten, those who are just being introduced to SR. Shane Or for Steven Wright when interviewing perspective employers.... Ya, so never mind then. I mean there was nothing to get as far as what I was talking about in the terms I hear it. Of course, all this stuff is really interesting. |
| 2014-03-23 6:52 AM in reply to: powerman |
Champion 9407 Montague Gold Mines, Nova Scotia | Subject: RE: Space, distance, time. ??? Here's an interesting video on the discovery: http://www.youtube.com/watch?v=4IlBNJbCzfk&sns=em Shane |
| 2014-03-23 1:55 PM in reply to: gsmacleod |
Elite 6387 | Subject: RE: Space, distance, time. ??? Originally posted by gsmacleod Here's an interesting video on the discovery: http://www.youtube.com/watch?v=4IlBNJbCzfk&sns=emShane That's really cool. the art work was awesome. |
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