# Faster-than-light space travel explained 201 **URL:** \ **Category:** In My Humble Opinion\ **Created:** [January 22, 2017, 11:42pm UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896 "2017-01-22T23:42:12Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [January 22, 2017, 11:42pm UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/1 "2017-01-22T23:42:12Z")
Prerequisite: Understand Einstein"s quote “spooky action at a distance”. If two particles are quantumly entangled; one on Earth, the other on a spacecraft, and both particles can be observed, then time dilation does not occur between these two reference frames, otherwise one could not influence the other instantaneously. So the spacecraft with the entangled particle is capable of exceeding the speed of light © relative to the position of the other entangled particle. This does not violate causality, because the two particles are synchronized by being entangled. The classic point A moving at 99% c sending a response to another point B at FTL before the original message was sent can’t happen, because now there is a “preferred” reference frame. Do the math, it doesn’t violate GR. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [January 23, 2017, 12:18am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/2 "2017-01-23T00:18:59Z")
I don’t know what the point of this post is, but everything in it is wrong. To wit: > [@](#): > > then time dilation does not occur Yes it does. If it didn’t, it would violate SR. > [@](#): > > otherwise one could not influence the other instantaneously. It doesn’t. Entanglement is not FTL communication. > [@](#): > > So the spacecraft with the entangled particle is capable of exceeding the speed of light (c) relative to the position of the other entangled particle. No it isn’t. > [@](#): > > This does not violate causality Yes, it would violate causality, if it were true. But it isn’t. ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [January 23, 2017, 12:53am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/3 "2017-01-23T00:53:24Z")
> [@wolfpup](#): > > I don’t know what the point of this post is, but everything in it is wrong. To wit: > Yes it does. If it didn’t, it would violate SR. > > It doesn’t. Entanglement is not FTL communication. > > No it isn’t. > > Yes, it would violate causality, if it were true. But it isn’t. The point of this post to hear what people have to say… SR requires that there is no “preferred” reference frame, so that part of your comment is true. Newtonian physics is true for relatively flat space-time. Entangled particles are a preferred reference frame. Entanglement doesn’t transmit information (you can’t send any information by observing the particle’s state) so of course that’s not FTL communication. But how do you know that entangled particles don’t change the frame of reference? And no, if two entangled particles cause a synchronized frame of reference, and I’m correct, then any FTL communication between the two synchronized frames of reference would not violate causality. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [January 23, 2017, 1:08am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/4 "2017-01-23T01:08:55Z")
> [@EastUmpqua](#): > > But how do you know that entangled particles don’t change the frame of reference? Absent any evidence that they do, and with no reason to think of any reason they might, the smart money is on them not doing so. You would need new physics, and evidence to base such new physics on. Just saying “how do you know there isn’t new physics?” isn’t useful. > [@](#): > > And no, if two entangled particles cause a synchronized frame of reference, and I’m correct, then any FTL communication between the two synchronized frames of reference would not violate causality. But they **don’t** transmit information, so the question of FTL communication is not relevant. This morning I woke up and was hungry. If I had had some bacon, I could have eaten bacon and eggs for breakfast. If I had some eggs. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [January 23, 2017, 1:13am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/5 "2017-01-23T01:13:56Z")
> [@EastUmpqua](#): > > And no, if two entangled particles cause a synchronized frame of reference, and I’m correct, then any FTL communication between the two synchronized frames of reference would not violate causality. Well, you can’t be correct because any two points separated in space are correspondingly separated in time. There is no absolute concept of synchronicity. Any such assumption is meaningless and does, in fact, violate causality. ---
**Author:** ![silenus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/silenus/32/166_2.png) [@silenus](https://boards.straightdope.com/u/silenus)\ **Post date:** [January 23, 2017, 1:26am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/6 "2017-01-23T01:26:40Z")
> [@EastUmpqua](#): > > The point of this post to hear what people have to say… What people are going to say is that you are totally, completely, absolutely wrong. ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [January 23, 2017, 1:43am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/7 "2017-01-23T01:43:06Z")
> [@Francis\_Vaughan](#): > > Absent any evidence that they do, and with no reason to think of any reason they might, the smart money is on them not doing so. You would need new physics, and evidence to base such new physics on. Just saying “how do you know there isn’t new physics?” isn’t useful. > > But they **don’t** transmit information, so the question of FTL communication is not relevant. > This morning I woke up and was hungry. If I had had some bacon, I could have eaten bacon and eggs for breakfast. If I had some eggs. I had bacon and eggs for breakfast this morning too… It’s a good thing no one wonders if there might be “new physics” because current physics explains dark energy, dark matter, and the unification of quantum physics and GR so well already. I can think of an experiment to test my theory; one entangled particle at a physics lab at Stanford and another in low-earth orbit, and both locations have the capacity to observe the entangled particle. If time dilation still occurs, then I’m wrong. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [January 23, 2017, 1:49am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/8 "2017-01-23T01:49:08Z")
How would the observers know they are observing simultaneously? ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [January 23, 2017, 2:05am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/9 "2017-01-23T02:05:39Z")
> [@EastUmpqua](#): > > It’s a good thing no one wonders if there might be “new physics” because current physics explains dark energy, dark matter, and the unification of quantum physics and GR so well already. Sure, we need new physics. But this doesn’t mean that every new idea is immediately accorded some special status. You are asking for new physics for no other reason than to support an idea of even more new physics. > [@](#): > > I can think of an experiment to test my theory; one entangled particle at a physics lab at Stanford and another in low-earth orbit, and both locations have the capacity to observe the entangled particle. If time dilation still occurs, then I’m wrong. Indeed. If you were to develop your idea to the point where it usefully explained an as yet unexplained problem (say one of: “dark energy, dark matter, and the unification of quantum physics and GR”) you might get some interest, and someone might even perform the experiment. (You don’t even need to orbit the second particle, just fly it around the Earth on a plane.) OTOH, you have a lot of work to do to develop a useful and consistent theory based upon your idea of synchronized frames of reference. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [January 23, 2017, 3:06pm UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/10 "2017-01-23T15:06:10Z")
> [@EastUmpqua](#): > > The point of this post to hear what people have to say… **Moderating** If you’re looking for opinions, then the best forum for this is IMHO. Colibri General Questions Moderator ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 23, 2017, 5:11pm UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/11 "2017-01-23T17:11:42Z")
How do you know that eating eggs for breakfast doesn’t change your reference frame? Answer that, and then we can try to address your points about entanglement. ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [January 24, 2017, 3:53am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/12 "2017-01-24T03:53:49Z")
Fixing eggs and bacon for breakfast has only very local effects; some IR radiation, some chemical reactions and a phase change. Quantum entangled particles can be separated by any distance (now no longer local like breakfast) and the observation of one of them instantly determines the state of the other one. The two entangled particles exist in a preferred (or synchronized) frame of reference… ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [January 24, 2017, 9:35am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/13 "2017-01-24T09:35:17Z")
Why is the following not the way to reconcile entanglement and special relativity? > [@](#): > > It is not even possible to unambiguously say which of the measurements came first. For two spacelike separated events x1 and x2 there are inertial frames in which x1 is first and others in which x2 is first. Therefore, the correlation between the two measurements cannot appropriately be explained as one measurement determining the other. Different observers would disagree about the role of cause and effect. > **[Quantum entanglement](https://en.wikipedia.org/wiki/Quantum_entanglement)** > > Quantum entanglement is the phenomenon of a group of particles being generated, interacting, or sharing spatial proximity in such a way that the quantum state of each particle of the group cannot be described independently of the state of the others, including when the particles are separated by a large distance. The topic of quantum entanglement is at the heart of the disparity between classical and quantum physics: entanglement is a primary feature of quantum mechanics not present in classica... According to this there is no way to test for time dilation in a quantum entanglement experiment. What do you know that they don’t? Or what do they know that you haven’t realized? ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [January 24, 2017, 10:14am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/14 "2017-01-24T10:14:20Z")
> [@EastUmpqua](#): > > Quantum entangled particles can be separated by any distance (now no longer local like breakfast) and the observation of one of them instantly determines the state of the other one. But there’s no fact of the matter regarding the observation of which particle ‘determines the state’ of the other (if you want to talk that way, which I would caution against). If the two particles are separated by a spacelike distance, then there exists a frame of reference in which the observation of A occurred before B, and a frame of reference in which the observation of B occurs before A. In the end, everything works out consistently (with the observations made at the other end, and with special relativity). ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 24, 2017, 11:21am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/15 "2017-01-24T11:21:31Z")
> [@Trinopus](#): > > How would the observers know they are observing simultaneously? This seems to be the nub of the confusion - I think the experiment being described here is: [ul] [li]Get two entangled particles[/li][li]Move one of them to a different reference frame[/li][li]Observe them both _simultaneously_…[/li][/ul] ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [January 24, 2017, 12:50pm UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/16 "2017-01-24T12:50:07Z")
> [@Mangetout](#): > > This seems to be the nub of the confusion - I think the experiment being described here is: > [ul] > [li]Get two entangled particles[/li][li]Move one of them to a different reference frame[/li][li]Observe them both _simultaneously_…[/li][/ul] I wouldn’t be shocked if it was the complete misunderstanding: - do something to one and observe exactly when the other changes ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 24, 2017, 1:34pm UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/17 "2017-01-24T13:34:17Z")
> [@naita](#): > > I wouldn’t be shocked if it was the complete misunderstanding: > > - do something to one and observe exactly when the other changes Yeah, I did wonder if there was some assumption that we can keep checking in on a quantum state to see if it’s collapsed yet, without actually forcing it to do so. (If we could, that would be cool, because that would enable FTL communication) ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [January 25, 2017, 2:53am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/18 "2017-01-25T02:53:12Z")
> [@naita](#): > > Why is the following not the way to reconcile entanglement and special relativity? > > [Quantum entanglement - Wikipedia](https://en.wikipedia.org/wiki/Quantum_entanglement) > > According to this there is no way to test for time dilation in a quantum entanglement experiment. What do you know that they don’t? Or what do they know that you haven’t realized? You quoted the Paradox section of the wiki article on quantum entanglement (the ERP paradox), but you quoted only one element of the paradox. This seems specious, or you didn’t read the article you quoted ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [January 25, 2017, 3:38am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/19 "2017-01-25T03:38:13Z")
FTL spacecraft would be cool… Experiment: One entangled particle is on a Boing 727 with equipment capable of measuring the state of its particle. The other entangled particle is in a lab at Stanford, also capable of measuring the state of its entangled particle. Both the plane and the lab also have very accurate clocks. Without actually measuring the state of either particle, compare the two clocks when the plane lands. If time dialation still occurs (the clocks are off by .00…1 seconds) in accordance with GR predictions, then my theory is wrong and no FTL communication or spacecraft are possible. But if the clocks read exactly the same, then the local reference frames, i.e. the plane and the lab, are synchronized (because when observed, either particle has to be able to affect the state of the other one instaneously) and time dialation doesn’t occur. Then FTL space travel is possible. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [January 25, 2017, 4:30am UTC](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896/20 "2017-01-25T04:30:52Z")
The two-clock experiment has occurred (without entangled particles.) Time dilation has been observed. Why would entangled particles “lock” the two clocks into synchronization? How would they do that? Why would a measly pair of electrons force space-time to become absolute? What happens to clocks in the vicinity of this effect: how widespread is it? Does the entire earth get locked into a single frame of reference? [Next page](https://boards.straightdope.com/t/faster-than-light-space-travel-explained-201/777896.md?page=2)