Time dilation basic

[zorphas]

Hello All,

 

First of all, sorry if this was asked before, it helps me when someone reads my answer the way I ask and answers it accordingly rather then reading questions that are "close" to what I'm asking.

 

I am REALLY trying to understand the theory of relativity and time dilation and I'm having some trouble since I can't find answers to a few specific questions - thought maybe you guys could help! A lot of my questions revolve around when time "Appears" to be different and when the effect is "Actually" real.

 

So here is what I've learned so far - please correct me if I'm wrong:

 

-The effect of mass/gravity on space/time somewhat makes sense to me. Basically, if the gravitational pull is effecting the space around where you are differently then another point, everything inside that space (including the atoms inside your body) will start moving differently and even though it seems like X amount of time has passed, relative to another point in space a different amount of time has passed. This is my understanding of how mass/gravity effects time, is this correct? Please explain in simple english if not, I am in no way a physicist or mathematician, I'm a programmer

 

---If I'm wrong about the whole "atoms inside you moving faster" what I don't understand is how can a human body who's particles are moving at the exact same speed age differently at a different point in space. Let's say 2 days at a certain point equals to 1 year on earth - it has to effect how the rate at which your body/molecules work for you to truly feel the difference and still age relatively to where you are, no? If that didn't happen then even though to the space around you it's 2 "days" to you it would still feel like 1 year and you would age accordingly.

 

-The distance between two objects also has an effect since light travels at a certain speed and it takes some time for it to go from point A to point B and so how fast you're moving and how far you are from a point can make it "LOOK" like there is a difference, but in reality you're just seeing the aftereffect since the light hasn't reached you yet... That does nothing to time as far as I'm concerned, just because you "SEE" something that happened X amount time ago later then it did, doesn't mean it is actually happening "now" even relative to you since your just seeing the aftereffect. For example, The stars that have blown up - are blown up. Just because we can see them still doesn't mean that they are there. So as far as I understand it, this theory has NOTHING to do with time travel - it has to do with when you see what and when.

 

Now... What I don't understand is - how does Velocity have anything to do with time dilation? Please don't give me a formula and say "LOOK AT C!!!!" I don't care about formulas even if they prove something, I just want to understand this at a logical level.

 

So you're telling me that if I were to move around the earth real fast - Not fly, no mass/gravity difference, stay in the same space and altitude as everyone else - just travel REALLY REALLY fast would that also dilate time? If not - then why do people say "Going fast will gain you time!" It sounds more to me like "By going to a certain point in space where space is effected differently by gravitational pulls - time dilates."

 

Again, I understand how moving fast will effect how you "SEE" something differently - but that doesn't mean anything in terms of time (at least to me). You may see it late/early but there is still a specific "Time" when the event occurred regardless how you see it. So, put simply, does velocity ALONE have any REAL (not visual) effect on time dilation and if so please explain it as simply as possible.

 

Sorry for the long read,

Thank you in advance!

[DrRocket]

Hello All,

 

First of all, sorry if this was asked before, it helps me when someone reads my answer the way I ask and answers it accordingly rather then reading questions that are "close" to what I'm asking.

 

I am REALLY trying to understand the theory of relativity and time dilation and I'm having some trouble since I can't find answers to a few specific questions - thought maybe you guys could help! A lot of my questions revolve around when time "Appears" to be different and when the effect is "Actually" real.

 

So here is what I've learned so far - please correct me if I'm wrong:

 

-The effect of mass/gravity on space/time somewhat makes sense to me. Basically, if the gravitational pull is effecting the space around where you are differently then another point, everything inside that space (including the atoms inside your body) will start moving differently and even though it seems like X amount of time has passed, relative to another point in space a different amount of time has passed. This is my understanding of how mass/gravity effects time, is this correct? Please explain in simple english if not, I am in no way a physicist or mathematician, I'm a programmer

 

---If I'm wrong about the whole "atoms inside you moving faster" what I don't understand is how can a human body who's particles are moving at the exact same speed age differently at a different point in space. Let's say 2 days at a certain point equals to 1 year on earth - it has to effect how the rate at which your body/molecules work for you to truly feel the difference and still age relatively to where you are, no? If that didn't happen then even though to the space around you it's 2 "days" to you it would still feel like 1 year and you would age accordingly.

 

-The distance between two objects also has an effect since light travels at a certain speed and it takes some time for it to go from point A to point B and so how fast you're moving and how far you are from a point can make it "LOOK" like there is a difference, but in reality you're just seeing the aftereffect since the light hasn't reached you yet... That does nothing to time as far as I'm concerned, just because you "SEE" something that happened X amount time ago later then it did, doesn't mean it is actually happening "now" even relative to you since your just seeing the aftereffect. For example, The stars that have blown up - are blown up. Just because we can see them still doesn't mean that they are there. So as far as I understand it, this theory has NOTHING to do with time travel - it has to do with when you see what and when.

 

Now... What I don't understand is - how does Velocity have anything to do with time dilation? Please don't give me a formula and say "LOOK AT C!!!!" I don't care about formulas even if they prove something, I just want to understand this at a logical level.

 

So you're telling me that if I were to move around the earth real fast - Not fly, no mass/gravity difference, stay in the same space and altitude as everyone else - just travel REALLY REALLY fast would that also dilate time? If not - then why do people say "Going fast will gain you time!" It sounds more to me like "By going to a certain point in space where space is effected differently by gravitational pulls - time dilates."

 

Again, I understand how moving fast will effect how you "SEE" something differently - but that doesn't mean anything in terms of time (at least to me). You may see it late/early but there is still a specific "Time" when the event occurred regardless how you see it. So, put simply, does velocity ALONE have any REAL (not visual) effect on time dilation and if so please explain it as simply as possible.

 

Sorry for the long read,

Thank you in advance!

 

You need to read a real book on special and general relativity. Rindler's Essential Relativity: Special Genertal and Cosmological would probably be suitable. It is not particularly demanding in terms of mathematics. There are too many misconceptions above to address each individually.

 

Einstein's theory of relativity is in large part a theory regarding the very nature of space and time. The effects of "time dilation"are real, and are not the result of any mechanistic change in anything, atoms included. Time really is observer-dependent, and it is a local, not global, concept. The same statement applies to space. This is not intuitive. It is backed by a mountain of empirical evidence.

[csmyth3025]

There is a Wikipedia article entitled "time dilation" that explains this effect as a consequence of velocity (Special Relativity) and gravity (General Relativity) here: http://en.wikipedia....i/Time_dilation

 

It explains it in more-or-less simple terms and it also includes some of the math involved if you want to go into that aspect of it. It also provides links to related Wikipedia articles (and links to external reference sites) that can provide more in-depth information.

 

The short answers to your questions are: Yes, time really does slow down for someone who is in a stronger gravitational field (like the Earth) compared to the time experienced by someone who is farther away (in a weaker gravitational field)....and....Yes, time really does slow down for someone who is going really fast relative to someone else. The second part of this answer is a bit more complicated - because each person will notice that the other person's time is running slower than his own. It would be better if you read through the Wikipedia article before we try to delve any deeper into these concepts.

 

These effects are very real and they are, in fact, proven every day by our use of Garmins, TomToms and other GPS (Global Positioning System) devices:

 

According to the theory of relativity, due to their constant movement and height relative to the Earth-centered, non-rotating approximately inertial reference frame, the clocks on the satellites are affected by their speed. Special relativity predicts that the frequency of the atomic clocks moving at GPS orbital speeds will tick more slowly than stationary ground clocks by a factor of , or result in a delay of about 7 μs/day, where the orbital velocity is v = 4 km/s, and c = the speed of light. The time dilation effect has been measured and verified using the GPS.

 

The effect of gravitational frequency shift on the GPS due to general relativity is that a clock closer to a massive object will be slower than a clock farther away. Applied to the GPS, the receivers are much closer to Earth than the satellites, causing the GPS clocks to be faster by a factor of 5×10^(-10), or about 45.9 μs/day. This gravitational frequency shift is noticeable.

 

When combining the time dilation and gravitational frequency shift, the discrepancy is about 38 microseconds per day.....(Comment added: the clocks on the GPS satelites tick about 38 microseconds per day faster than the clocks on the ground)...

(ref. http://en.wikipedia....eral_relativity )

 

Chris

[zorphas]

Thanks for the replies!

 

I've read through that and understand how altitude and gravitational pull effects space and everything inside it and in turn time is dilated, but what about if someone is in the SAME exact gravitational pull but going really fast? Say you have a car that goes round and round ON earth very fast, that's what confuses me. Altitude and gravitational pull can have an effect on how fast EVERYTHING moves within a certain space which makes it understandable why time would actually be different, it's the speed part I don't understand. What if you were standing still in a space that has a different gravitational pull? What if you were going real fast inside the same space - or does speeding change the effect of gravitational pull?

 

I actually THINK I may have answered my own question with that last question: Does velocity affect the gravitational pull on the space traveling at that speed? So if I'm traveling in a car that can go REALLY fast, would the space inside that car be different then the space around it the same exact way space is bent in space but in a much lower scale?

 

Another thing I'm having trouble grasping is the fact that light speed doesn't really fall under the same rules as relativity - it's always constant regardless of the observer's perspective. That's just weird, how can that be possible?

 

Thanks!

[DrRocket]

Thanks for the replies!

 

I've read through that and understand how altitude and gravitational pull effects space and everything inside it and in turn time is dilated, but what about if someone is in the SAME exact gravitational pull but going really fast? Say you have a car that goes round and round ON earth very fast, that's what confuses me. Altitude and gravitational pull can have an effect on how fast EVERYTHING moves within a certain space which makes it understandable why time would actually be different, it's the speed part I don't understand. What if you were standing still in a space that has a different gravitational pull? What if you were going real fast inside the same space - or does speeding change the effect of gravitational pull?

 

I actually THINK I may have answered my own question with that last question: Does velocity affect the gravitational pull on the space traveling at that speed? So if I'm traveling in a car that can go REALLY fast, would the space inside that car be different then the space around it the same exact way space is bent in space but in a much lower scale?

 

Another thing I'm having trouble grasping is the fact that light speed doesn't really fall under the same rules as relativity - it's always constant regardless of the observer's perspective. That's just weird, how can that be possible?

 

Thanks!

 

 

You definitely need to read the book.

[Janus]

Thanks for the replies!

 

I've read through that and understand how altitude and gravitational pull effects space and everything inside it and in turn time is dilated, but what about if someone is in the SAME exact gravitational pull but going really fast? Say you have a car that goes round and round ON earth very fast, that's what confuses me. Altitude and gravitational pull can have an effect on how fast EVERYTHING moves within a certain space which makes it understandable why time would actually be different, it's the speed part I don't understand.

 

Actually, that's not how gravitational time dialtion operates. It is related to the difference in gravitational potential not gravitational strength. To illustrate, consider a hypothetical "uniform" gravity field, or in other words, a gravityi field that does not decreae in strength with altitude. If you put two clocks in this field at different heights in the field, they will have a different potential (you would have had to expend energy to lift the lower clock to meet the upper clock.)

 

In this example, the higher clock will run faster than the lower clock due to gravitational time dilation, even though both clocks experience exactly the same gravitational pull.