<p>^Sorry. We always do this. You’re lucky to have gotten no “chundered everywhere” talk.</p>
<p>There is no such thing as “time”. We just make it physical because it’s easier for everyday life. Think of it. There is no such real thing as past/present/future.</p>
<p>Right now is present. < is the past. The future is right now as I type this. And again… and again… < is the past. and again…</p>
<p>Only the mind/living spirit can “create” time through memories and thoughts. Ugh confusing…</p>
<p>It’s okay, Millancad. It’s all fine.
aStyle: That is a good philosophical point you brought up. I talked about this once to some senior citizens I speak to.
Suppose there is no time. Then how do we know that we progressed? Then how do we suppose that change occurred? Why is there death? What about string theory? What about the time dimension (which is either the 4th, 10th, 11th, 12th, or 13th dimension depending on what type of physics you fixate yourself to)?</p>
<p>And my biggest statement: What about duration? If time does not exist, there is still duration in any context of anything. And how do we measure duration? Through… (drumroll)… TIME!</p>
<p>(Applause, Flourish, Exeunt)</p>
<p>Thank you very much for bringing up that point aStyle. I appreciate it very deeply.</p>
<p>Hmm yes. I think before one can embark on any sort of question of time-travel, one must define the concept of time, or what exactly we are traveling through to reach ahead in time. We define time, by a point set by humans. Everything else after or before is relative to that point.</p>
<p>So my essential question is what are defining time to be? (if it even exists)</p>
<p>Of course time travel can exist. That’s why we have multiverses : ) </p>
<p>And free will, well, the existence of a future does not make it impossible. Suppose a person comes from the future to our time and wreaks havoc. He creates a new universe right then and there. Your future is only affected in that one universe and perhaps/MAYBE ceases to exist in only that universe. (I’m not sure about this one : /)</p>
<p>Hello Esplin: Yes, but doesn’t that show that since there are so many different possibilities that a universe can take due to string theory or the Creator, isn’t free needed to make all those different possibilities? A set predestination will entail only a couple of possibilities, whereas free will allows for infinite possibilities which works in science and religion.
With your model of the scientist, as I stated before, he would cease to exist before time travelling anyway due to the mass problem. If he was able to time travel anyway, we wouldn’t realize it and we would cease existence. End of story.</p>
<p>I personally believe that Allah, or God, gave man free will and Allah knows where we’ll go, but since Allah knows where we’ll go but doesn’t forces us to go there, we have free will but will end up where we’re supposed to. </p>
<p>Come on guys! Join in the fun that is physics!</p>
<p>Now I said two things that you thought you would never hear before (look at form of government thread).</p>
<p>I agree that the current lack of visitors from the future proves that either time travel is impossible for humans, or else future generations will never choose to visit us in a noticable way. From what I know of human nature, the latter case seems unlikely. Just think how much fun you could have as a 21st century visitor to ancient rome! But since time may only be a fouth dimension, it’s being only passable in one direction for us humans doesn’t rule out the existence of beings that CAN travel through it.</p>
<p>Hello MosbyMarion: In I believe my first post, I reference wormholes which would allow for spacial and fourth (or 10th, 11th, 12th, or 13th)-dimensional travel, but the mass problem would just destroy everything.</p>
<p>If I’m remembering correctly there is an African English (political correctness shall overcome great struggles of ignorance) physics professor at Oxford who is trying to create time travel through slowing down light. So far his experimentations are not working at all and companies who once supported him are freezing his funds.</p>
<p>I think pretty much time travel (INTO THE FAR FUTURE OR PAST) could not work under any set conditions.
Conclusion: We move in the fourth dimension at a set rate and forwards (or what we perceive to be forwards) direction, just as antiparticles move at a set rate in a backwards direction. Time travel may occur only in the same direction as the particles one’s body is composed of and can occur at faster rates than the particles move at through the use of wormholes or other spacial phenomena, but since speed of light travel causes mass to accumulate and then dissipate into energy which causes us to turn into massless photons, time travel for objects may not exist. </p>
<p>If anyone can refute that statement, please do! I would love an argument like this. </p>
<p>What about sending messages through time travel (either through sound or brain waves)?
I have a really great conversation about this one as well, but I want some College Confidential users to have some fun too!!</p>
<p>It has been shown at MIT that teleportation of particles and energy works, at the quantum scale. I’m not exactly certain how this is done, but it doesn’t involve faster-than-light travel. I’m not sure what this has to do with anything, but I thought it was interesting.</p>
<p>Anyways, the next time anyone figures out to harness a tachyon’s mysterious powers to break the barriers of general relativity, kindly let me know.</p>
<p>^ I’ll do that :P</p>
<p>when u say past, its any where back in the time curve.When u move past a second, you will have moved past a second.in fact,u have moved past a past.Einstein’s special relativity postulate ironically came up with the hypothesis that we can travel back in time(no idea bout the future though) .when u travel at the speed of light,others will have aged while ur cells and tissues still remain the same.in a spatial time frame, u r in the past with respect to others.technically, time travel is possible.</p>
<p>I know that this is a very misunderstood topic, but try to refrain from blurring the line between science and mysticism (not that this may have happened here, it’s just a tendency when talking about these things). </p>
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<p>Your limiting the definition of time to something that exists only for semantics. Time exists independently of human thought; it can be described, however, relative to perception, much like how the dimensions of space, although existing independently, can be described as left and right or up and down. Time exists as a dimension related to space (you would agree that it takes time to move from one point to another, as the OP pointed out in his “duration” post).</p>
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<p>Experiments in slowing down light has already occurred and been proven successful by Lene Hau, who ran photons through certain particles in the form of a superfluid cooled to near 0K temperatures. I’m not sure if this relates to time-travel though, and probably has more potential in quantum teleportation. [source:<a href=“http://www.wired.com/science/discoveries/magazine/15-11/st_alphageek][/url”>Harvard Physicist Plays Magician With the Speed of Light | WIRED][/url</a>]</p>
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<p>If I remember correctly, physicists used the properties of quantum entanglement, which only relates information from one particle (such as spin) to another particle instead of actually “teleporting” it. It may or may not help build a time machine, but it can be used in quantum computing. </p>
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<p>As someone stated earlier, the problem of paradoxes can be eliminated if we accept the hypothesis of the multiverse. Provided we don’t run into any more problems regarding physics, and provided we have enough energy to create a time machine, time travel should be theoretically possible.</p>
<p>Time is relative to speed, so we don’t move through time at a set rate. Although Einstein may have referred to time as a “flowing river,” some quantum physicists (Brian Greene) have reason to believe in a “frozen river,” in which all events of time exist simultaneously. I’ll repost the metaphor he used later as I remember it. [source: Greene, The Fabric of the Cosmos]</p>
<p>The speed of light doesn’t cause matter to lose its mass; photons must lack mass in order to reach the speed of light. I don’t remember the arguments behind it, but physicists argue that matter reaching the speed of light is theoretically impossible (particles that exist at speeds faster than light do hypothetically exist - see tachyons). There are plenty of ideas for time travel that don’t revolve on faster-than-light travel, however, as one poster suggested before.</p>
<p>^Ugh. Does anyone else find it sick how smart he is? :)</p>
<p>If time travel were to occur (based off of what I know):</p>
<ol>
<li>We would need vast amounts of energy.
2a. The multiverse hypotheis is true, and paradoxes wouldn’t occur.
2b. Time travel to the past exists, but events outside of your control inevitably occur to prevent any paradoxes from occurring (e.g., you try to travel back in time to prevent your parents from meeting, but are instead shot and killed before you find them). </li>
<li>Time travel cannot occur past the creation of the time machine.
4a. Faster-than-light travel for matter is possible.
4b. Wormholes exist, and can be used safely.
4c. String theory provides us with a deus ex machina.</li>
</ol>
<p>I’m sure there are a few points I missed though. I’ll try to remember them as this thread goes along.</p>
<p>Lol, thanks randomazn.</p>
<p>“Does Time Flow” - Brian Greene’s The Fabric of the Cosmos, chapter 5.</p>
<p>(paraphrased, with possible reinterpretations, with provided information subject to my memory) </p>
<p>Brian Greene related spacetime to both a loaf of bread and a frozen river. Imagine taking all of spacetime and representing it as a loaf of bread. This loaf of bread could be cut into slices, each representing a “now” slice for that particular observer. These slices could be cut at different angles, representing changes in time (as time dilation) for two observers separated by both space and velocity. </p>
<p>Now, imagine that you an an alien observer are both sitting, with velocities of zero relative to each other (hold all other motion zero, if you wish, as this is just a thought experiment), at an immense distance apart. Because both of you are a set distance apart and neither of you are in motion, your “now-slices” coincide, and your perception of time remains the same. Now, if the other observer begins moving at a rate away from you, his “now-slice” experiences a slight change in angle. To those in his vicinity, time-slices are for all intents and purposes the same. Magnified over this distance (remember that space and time are always related), there is now a discrepancy between your idea of the present and his idea.</p>
<p>Using special relativity, we determine that when he moves away relative to you, what he experiences in his “now” timeframe is what you experienced in the past. Over vast amounts of distances, this can mean that at one moment, you and the observer both exist simultaneously, while at another, you may not have even been born. </p>
<p>This has further implications, and calls into question the concept of free will. In another chapter, Greene suggests that if a being could know all the quantum wavefunctions of every single particle, that being would have a fully deterministic view of everything in past, present, and future. </p>
<hr>
<p>Of course, this all rests on the idea that string theory is a valid description of the universe, and that Brian Greene knows what he’s talking about.</p>
<p>With quantum teleportation: AeroEngineer3141 already explained about quantum entanglement. However, scientists have also recognized something called quantum weirdness where these subatomic particles do not follow set parameters that physics imposes and under go these oddities at this level. This can cause probability to occur in our world (however string theory is more widely accepted) and may cause multiverses.
AeroEngineer3141: I’ve been trying to find the name of that African English professor, but apparently he died in the 1960s so his work can’t go on. And I’m not talking about paradoxes with the mass problem. I’ve read Greene’s book about string theory and he also expressed how traveling near the speed of light increases mass, which causes energy dissipation. This always works in a multiverse situation due to the innate fact of quantum gravitation. I realize this uses Einstein’s theory of relativity to support it however, but Greene (in the “Elegant Universe” which I preferred more to “Fabric of the Cosmos” and several other string theorists state that both String Theory and the Theory of Relativity need to be taken as true to create the TOE. I also realize that if you use the multiverse model than Lorentz Contraction and Time Dilation can’t exist. I also know that physicists argue that traveling near the speed of light is impossible for obvious reasons. Take a look at Special Relativity once more: Massless particles like gauge bosons (though gluons aren’t really free moving particles). Massless particles that move freely (call them luxons or non-bradyons if you like, Mr. Feynman–I have to have some fun) always move at the speed of light and undergo gravitational acceleration which makes them have RELATIVISTIC mass, acting as gravity upon them. This allows for gravitational lensing, or when light bends so to speak. Because of this, they do not seem to be massless particles and move at the speed of light—but only to the quantum observer–NOT the laws of science. I’ve read about Lene Hau’s experiments which heavily rely on gravitational lensing. About quantum computers: The non-existence of time travel does not refuse the existence of quantum computing. That would be a Non-sequitur argument.
About the “Frozen River” argument: I knew someone would bring that up. And here’s my response: have you ever read “Flowing with a Frozen River?” It’s an interesting read that brings up this argument. The other uses causality to prove that time is both flowing AND frozen. Just like light being both a wave and a particle or a particle with wave elements or a wave with particle elements, time moves as a frozen river with flowing elements, as a flowing river and some parts froze, or that they are both theories equally accepted.
“The time is flowing, and it is frozen” (Stoica 6).
The quantum observer believes that time is flowing because we can observe change, where as the laws of physics is more inclined to the frozen example. Thanks to the principles of String Theory and The Theory of Relativity, we can accept both without any confrontation whatsoever.
You can read it here:
<a href=“http://www.fqxi.org/data/essay-contest-files/Stoica_flowzen_time_2.pdf[/url]”>http://www.fqxi.org/data/essay-contest-files/Stoica_flowzen_time_2.pdf</a> (I have this essay saved on my flash drive… is that pathetic?)
About tachyons: They are hypothetical particles and no experimental evidence has shown for them to exist or not to exist. Nonetheless, they probably do not because that would violate the law of causality in Special Relativity.</p>
<p>That was a lot of stuff I remembered… now my brain is yearning for a break, some honey, some chocolate, and milk. I’ll come back see what’s posted after I post this.</p>
<p>You make a great person to discuss science with! And you’re really smart too! Are you at MIT or some prestigious university? If you are a high school student, you seriously are a genius!</p>
<p>^^ Eh I read through most of that post. I’m guessing it’s trying to explain how time can be represented as a flow of something. But that explanation doesn’t really make sense. Because if time were a flow of something what exactly is it flowing past? And typically when we refer to a flow, it’s some quantity over time. Defining time, using time simply doesn’t make sense.</p>
<p>Okay I re-read the entire post, and I think my points still hold.</p>
<p>I saw your new post there AeroEngineer3141. You never cease to amaze me with your intelligence. Your statement allows my statement (especially about differences of quantum observers) to exist. Of course, the “Flowing with a Frozen River” essay is based entirely on String Theory where as Greene bases his ideas on String Theory. All quantum physicists today support that both theories must exist together for the universe to be perfect and stable, but some are more fond of the other. If only there was another great mind who took the time to become well immersed in both subjects. I’m sure you and I both read much about these theories but focused more on one than the other. I liked String Theory very much but because it’s a new theory with not that much information, I stuck to Einstein and Relativity. Apparently, you seem more well versed in String Theory. </p>
<p>It would be funny if Brian Greene found this thread, started an account, discussed with us about his ideas, and then prove us both wrong or right depending on whether he was flattered or disgusted by talking about him. Oh well… LET THE PHYSICS GO ON!</p>
<p>meadow36: Everything that exists in the time dimension flows down the river of time. The flow of the river is not being used to define time, in fact time is being used to define the laws of physics that occurs in the flow of the river.</p>
<p>Oh, I forgot to say that objects at rest are technically going at the speed of light due to Einstein’s theory of relativity due to Mass-Energy equivalence. </p>
<p>HEAD SPINNING
TOO MANY FACTS
MUST DRINK MORE MILK (I take a glass of milk and drink it like Link from LOZ)</p>
<p>Let’s take the definition of time tangent.</p>
<p>You’re absolutely right; there’s not really a definition of time. In fact, I doubt that time is an intrinsic property of the universe. Like math, time is only a concept that scientists have created to make sense of the world around us.</p>
<p>So what is time? What do we mean when we say time? Time is just a change in entropy. According to one of the laws of thermodynamics (the second?) the universe always tends to greater entropy. And thus, when we refer to “time”, we refer to an increase in entropy. How else could we tell that a recording of an amorphous blob of water rising back up by itself into a cup is played backwards?</p>
<p>Muhammad are you a high school student? Undergrad? Grad Student?</p>
<p>Same question for AeroEngineer</p>
<p>If you two are high schoolers I have some major catching up to do in physics.</p>