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Question about time and measurement

  1. Sep 27, 2013 #1
    Hi PF people,
    I am brand new to PF and this is my first post so please excuse and help correct any mistakes I make.
    My question is about time, the perception of time and the units we measure it in.
    I figured I would start this question with a statement because if my general understanding of this is wrong then this may be the problem to begin with.

    So lets use two objects. One is travelling at high velocity and one slow. My understanding is that the object going slower will experience more units of time than the object going fast.

    If this is true then my next question is do other planets (specifically in our solar system) experience the same passage of time?
    If not does this mean if another earth were duplicated and was traveling slower that these earth2 people would be many generations ahead of us?
    If so does this mean that they are all traveling at the same speed due to the gravity of our sun?
    Or that our solar system as a grouped unit is traveling at one speed?
    Or that our Galaxy has an inherent velocity?

    If our sun was also moving would time slow down as we went in the opposite direction our sun was travelling during our elliptical orbit?
    And I would guess this would mean when we change velocity in any way we are leaving a time frame dimension or membrane or something?

    Can someone actually just explain to me the whole time and speed thing?
    is time a byproduct of speed? or is speed a byproduct of time? do they both just have to exist the way they do for anything to move or BE at all?

    im sorry for the annoying way these questions were laid out, this is my first post and I didnt even complete highschool.
     
  2. jcsd
  3. Sep 27, 2013 #2
    I just want to add.
    If I were Dumbledore with a physics degree and created two clocks completely made of entangled particles so they were identical. I then make a spaceship and launch one of these clocks away at a very fast speed.
    Would the clocks read the fast moving slow time, or the slow moving fast time?
    Furthermore if i made a bar of copper+entangled duplicate, sent one with the clock, then put an electrical current through the one I kept with me, what would happen to the spaceship copper?
    Does this create entangled electrons from a spooky distance?
     
  4. Sep 27, 2013 #3

    Nugatory

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    It's not true.
    There's another fairly recent thread on this: https://www.physicsforums.com/showthread.php?t=712960
     
  5. Sep 27, 2013 #4
    Lol, thank you Nugatory. This those answers seemed logical. We have to stop watching Brian Greene talk about stuff.
     
  6. Sep 28, 2013 #5
    Hi welcome to physicsforums. :smile:

    That is quite correct if you measure as follows:

    A------------------------------B

    Let's say that you have two identical atomic clocks with identical readings at point A. Now clock 1 is moved fast from A to B, and clock 2 is moved slowly from A to B. Then you compare the two clocks at B and you will find that clock 1 is behind on clock 2. In other words, the clock that moved slower will have recorded more units of time than the clock that moved fast.

    Most other questions are perhaps covered in the other thread.
    Time and speed are human made concepts; most probably the universe doesn't depend on our existence. If nothing moved at all then there would be no speed to be measured. And as time measurements are based on motion, there also would be no time.

    I don't know if that is possible. And as your question involves SR+QM, that is a question to ask in the general physics forum.
     
  7. Sep 29, 2013 #6
    Thanks Harrylin I will move this question to general physics.
    The way you explained that brings up my previous questions again it seems.
    Although the objects I was describing weren't traveling from one point to another. The way you explained it is obvious, the slower object didn't reach the point B spot till much later and would obviously count more units of time.
    Really what i thought was happening was if an outside observer were to look at both the clocks (and he had a clock) and after a certain amount of time by his clock, he would check the clocks of the 2 moving objects and see if there was a discrepancy.
    I was listening to Ray Kurzweil spiel off about obvious stuff (no disrespect, hes brilliant, but his singularity theory is just an inevitable outcome of any form of education) and he said " an astronaut that orbits the earth at a fast rate will actually experience less time than the people on earth, not just his perception but actual clocks".

    This actually seems to be a very commons misconception. The closer you come to the speed of light the less time you experience in comparison to a slow object.

    Anyways, you say time and speed are human made concepts. Not really man, i would say they are the words we use to describe something thats actually happening.

    even a non sentient object will experience time. Thorium breaks down for example. I am sure they can "experience" speed as well.
     
  8. Sep 29, 2013 #7

    Drakkith

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    From here: http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html
     
  9. Sep 30, 2013 #8
    That's not what I wrote. Instead, I wrote that the two clocks that started out synchronously are out of sync after the travel. Indeed, according to the "rest frame" measurements, the faster moving clock ticked slower during the journey than the slower moving clock. I thought that perhaps that was what you had in mind.
    Yes, that is also correct, if the outside observer uses an inertial reference system for measurements and he/she "sees" by means of making a standard assumption about the time delay for the signals of those distant clocks to reach his/her clock. But since you had not mentioned a third clock, I interpreted what you said such that it was possible to compare the two clocks side by side. That's much simpler and more direct, as you don't need to make assumptions about signal transfer.
    See Drakkith's reply. If you try to understand special relativity, astronauts in orbit can be confusing as there you have to do with general relativity: the higher you are the faster your clocks tick. That makes it more complex, and not good for learning SR.
    Yes of course, those concepts are based on observations; and for sure, without observing motion we cannot create the concept of time. And our understanding and description of what is actually happening has changed with relativity theory.
     
    Last edited: Sep 30, 2013
  10. Sep 30, 2013 #9

    Dale

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    They would each read their own proper time. Entanglement doesn't change anything locally observable on either particle or ensemble.
     
  11. Sep 30, 2013 #10
    Thanks again Harrylin,
    So I am not good at interpreting what is being said to me I think.
    So what you and Drakkith are saying is that a sort of gravity-friction slows down the mechanism the clock runs by?
    Atom oscillations or however these clocks run, move faster away from the space-time warp caused by our massive earth?
    Because if they move faster away from earth that is the opposite of what I thought.
    I thought the faster you were going the slower time would tick.

    Lets say we had two musicians with perfect timing, one on earth and one in a fast orbiting spaceship. Would they experience a difference in time?
    I am just trying to think of a non mechanical clock or some way to ask this question better.

    DaleSpam, maybe I dont understand entanglement. If the two clocks were entangled does this not mean whatever one clock does the other has to do?
    If one was in a denser gravity field it would be subject to different environmental variables. Like, would this break entanglement or would one clock decide what time both clocks display?

    I really appreciate u three taking the time to read and post.
    Should I move this question to GR? or once its posted its kind of too late or what?
     
  12. Sep 30, 2013 #11

    Drakkith

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    No, it's just stand time dilation due to relative motion and gravity.

    The orbiting satellites are ticking slower because they are moving relative to us, AND they are they are ticking faster because they are further away from Earth and experience less gravity.

    Yes, they would experience a difference in the passage of time.

    No, not at all. That's not how entanglement works, but I'm afraid explaining it is not my specialty. Hit up the Quantum Physics forums and you should be able to find plenty of info on it.
     
  13. Sep 30, 2013 #12
    Quite the contrary. :wink:
    While Drakkith thinks that you can already handle the complexity of two different time dilation effects, I suggested to stick to special relativity's time dilation - ignore the effects of gravitation on "time". You can do that if your objects stay roughly at the same altitude. Then you have for example the measurement situation that I described. No gravity effects and thus also no space-time warps, and no friction effects. Just plain time dilation from speed. If you try to learn one thing at a time, there is a chance that you may actually progress. Except of course if you are a genius, then you can perhaps handle everything at once. :tongue2:

    That is an imprecise formulation of what I told you twice with a precise description of measurements ...

    Also what you ask next is too imprecise to know what you are asking. As a matter of fact, such imprecise descriptions result in misunderstandings such that two people can give contrary answers because they understand what you say inversely - compare posts and !
     
  14. Sep 30, 2013 #13
    Quite the contrary. :wink:
    While Drakkith thinks that you can already handle the complexity of two different time dilation effects, I suggested to stick to special relativity's time dilation - ignore the effects of gravitation on "time". You can do that if your objects stay roughly at the same altitude. Then you have for example the measurement situation that I described. No gravity effects and thus also no space-time warps, and no friction effects. Just plain time dilation from speed. If you try to learn one thing at a time, there is a chance that you may actually progress. Except of course if you are a genius, then you can perhaps handle everything at once. :tongue2:

    That is an imprecise formulation of what I told you twice with a precise description of measurements ...

    Also what you ask next is too imprecise to know what you are asking. As a matter of fact, such imprecise descriptions result in misunderstandings such that two people can give contrary answers because they understand what you say inversely - compare posts 3 and 5!
     
  15. Sep 30, 2013 #14
    hahaha i was comparing these posts and did find it confusing . What I understand now is that I dont understand this and need to read up a bit lol.
    I am definitely not a genius.

    So special relativity and time dilation. I will re-read what you have said, too.
    Thanks man
    Since you are answering so diligently though, could you explain why my questions about measuring time on other planets, and the whole earth 2 getting more work done than earth1 people question?
    It almost sounds like what I asked is possible...
     
  16. Sep 30, 2013 #15
    so upon further reading I am more confused. but I think it is a good thing.

    So do we consider the earth " at rest" ?
    Based on what I have read is it accurate to say that if we could bring a golf ball to absolute zero (i know this isnt possible, I have seen the helium videos, very cool) that everything would age infinitely to the golf ball? assuming we dont unfreeze it.
    Or inversely that if we could reach the speed of light time would stop?

    I am going to be honest, the real reason I am asking is because I have a question about Drakes equation ( how many forms of intelligent life are in the universe) and a little part at the end of the explanation where you can multiply this by how many times a single planet could produce intelligent life.
    I guess the theory is if a planet can produce one intelligent life form then why not another, or 100?
    Anyways, im wondering how accurate this little thing could be (i know not very accurate considering what it is trying to figure out) if they do not take the velocity of these objects (planets) into account over all the years.
     
  17. Sep 30, 2013 #16

    Dale

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    No. Entanglement is a quantum mechanical phenomenon. If you have some property which is quantum-mechanically uncertain, e.g. the polarization of some photon, and if you produce entangled particles, then if you measure the property you will find that the measured property on one is perfectly correlated with the measured property on the entangled partner.

    However, each ensemble, on its own, is simply random. It is only when you get the information from the other ensemble that you can obtain the correlations. This is what prevents any instantaneous information transfer through entanglement.
     
  18. Sep 30, 2013 #17

    Drakkith

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    For everyday little things we can consider the Earth to be at rest, but there is no "absolute" rest frame.

    What? Absolute zero has nothing to do with this, that is temperature.

    Since we have only a single planet with a single intelligent species it is impossible to come up with any conclusions that aren't simply guesses.
     
  19. Sep 30, 2013 #18

    WannabeNewton

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    The Earth is obviously at rest in its own rest frame by definition. The question is not whether one can consider it to be "at rest" because every massive object has a rest frame. The question is whether one can consider it an inertial frame, which one can approximately.
     
  20. Sep 30, 2013 #19
    Right, so when I said absolute zero i mean not moving, not even the atoms and electrons, no velocity.
    sorry it wasn't the right word at all.
    In many fields of physics you smart guys are spending a huge amount of time trying to make conclusions based on guesses though.
    And based on the two theories that I am aware of life can start from extremophile bacteria on a meteor, or possibly in the presence of amino acids and a specific frequency or something.
    In any case we are just guessing about planets at a certain distance from the start they orbit which potentially have water. These are the planets we would guess have an environment and atmosphere capable of sustaining life.
    In any case my question isn't about the validity of the drake equation, that's why I didn't bring it up in the initial post.
    WannabeNewton that is very interesting, it was something I was going to ask. Can we figure out how fast we are moving based on our time experience or something?
    My big questions are, do other planets in our solar system experience time differently?
    And my ultimate sci-fi curiosity is; if there was a planet in the goldy-locks zone or w.e its called which was inhabited by intelligent life and orbiting its star at a very slow velocity, would these guys be way ahead?
    how far can we take this time dilation thing?
     
    Last edited: Sep 30, 2013
  21. Sep 30, 2013 #20

    Drakkith

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    The motion of the particles that make up an object do not affect whether that object experiences time dilation. It is only the relative motion of the object as a whole.

    We could if we had an absolute frame of reference that everything could be compared against. But there is not.

    Sure. Both SR and GR effects will determine how quickly time passes anywhere, even on other planets. But this is no different than here on Earth. If I climb to the top of one of the nearby mountains I will be experiencing time at a faster rate than someone down at the base. These effects are always present, they are simply too small to detect without very precise clocks.

    Even the fastest orbiting planets are still moving at a VERY VERY small percentage of the speed of light. As such, the differences in elapsed time per day would be measured in nanoseconds or microseconds even when comparing ourselves to the fastest planets.
     
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