# Can one theoretically travel faster than light relativistically? **URL:** \ **Category:** Factual Questions\ **Created:** [September 3, 2021, 5:41pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057 "2021-09-03T17:41:45Z")\ **Posts on this page:** 20\ **Page:** 14
**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:** [November 4, 2021, 8:13am UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/264 "2021-11-04T08:13:13Z")
> [@tomh4040](#): > > A clear contradiction as the theory requires each of two identical clocks to be slower than the other. it’s ONLY a contradiction in some imaginary third privileged reference frame that can supposedly see and compare both clocks at once. It doesn’t exist. As everyone has already pointed out, this privileged reference frame is your own fiction, not part of the answer you were given. If you impose a third reference frame (which you did), then you have to state how that frame is behaving relative to the two clocks, and the observations from that frame will not be the same as they are from clocks A and B (and will not observe the contradiction that you state). So… describe the reference frame from which you are observing the contradiction, please. ---
**Author:** ![Cheesesteak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cheesesteak/32/3694_2.png) [@Cheesesteak](https://boards.straightdope.com/u/Cheesesteak)\ **Post date:** [November 4, 2021, 10:36am UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/265 "2021-11-04T10:36:44Z")
> [@tomh4040](#): > > A runs slower than clock B, and clock B runs slower than clock A. A clear contradiction This is an absolutist statement. There is no one absolute truth, no one absolute reality. What is real is relative, and it changes depending on the frame of reference. Here’s an analogy that may have already been used. I’m on a train approaching a location. My twin is at the location, we both have identical whistles, and blow them alternately. Which whistle has the lower pitch? I hear my whistle at the lower pitch, my twin hears his whistle at the lower pitch. I can have sensitive equipment show my whistle at 1,000Hz and his at 1,200Hz, and he can have equipment to show his at 1,000Hz and mine at 1,200Hz. There’s nothing imaginary about that 1,200Hz soundwave, either of them. ---
**Author:** ![tomh4040](https://avatars.discourse-cdn.com/v4/letter/t/ee7513/32.png) [@tomh4040](https://boards.straightdope.com/u/tomh4040)\ **Post date:** [November 4, 2021, 10:46am UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/266 "2021-11-04T10:46:42Z")
The point you (all) seem to be missing is that I am not a relativist. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [November 4, 2021, 10:54am UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/267 "2021-11-04T10:54:16Z")
That is irrelevant. You are like an English person asking for the German word for “light” but insisting it must be in English. And then when told the word in German you say “But I’m English, give me the German word in English!” and “You are speaking like a German, you are missing that I’m English!” ---
**Author:** ![tomh4040](https://avatars.discourse-cdn.com/v4/letter/t/ee7513/32.png) [@tomh4040](https://boards.straightdope.com/u/tomh4040)\ **Post date:** [November 4, 2021, 11:23am UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/268 "2021-11-04T11:23:08Z")
Relativity may or may not be internally consistent, but it definitely does not make real life predictions. That is what this whole discussion is about. In real life clock A cannot run faster than clock B while clock B runs faster than clock A. Einstein says they can, and uses his equation :- t = 1 / sqrt( 1 - ( v^2 / c^2 ) ) to prove that clock A runs slower than clock B. As the situation is symmetrical, the same equation can be used to prove that clock B runs slower than clock A. Einstein stated that these effects are real, but there cannot be a real situation where A \> B and B \> A. ---
**Author:** ![tomh4040](https://avatars.discourse-cdn.com/v4/letter/t/ee7513/32.png) [@tomh4040](https://boards.straightdope.com/u/tomh4040)\ **Post date:** [November 4, 2021, 11:34am UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/269 "2021-11-04T11:34:14Z")
I did say in a previous reply that I would get the answer to you in a day’s time. Here it is, although I guarantee you will not like or accept it :- You may be talking about the Frish and Smith experiment. Here is a summary of it. The muons coming down through the atmosphere may not be going just under light speed, but somewhat faster. In this way the muons will travel a greater distance before decaying. E.g. a muon going at double light speed will travel 1200m before decaying, a muon going at 10 **c** will go 6000m, etc. This possibility would likely strike a relativity supporter as absurd. So much so, that they would probably not even consider it in the first place. One reason for this has to do with conditioned thinking. Another (more scientific) reason though is because the speed of the muons has already been measured and seen to be less than light. But is that really the case? Now it is true to say that, once in the scintillator we can measure the muon’s speed because we have a distance and a time. But keep in mind that the muons at this point have been slowed down from their original assumed speed of 0.995 **c** and are now going much slower. Based on the fact that some of them decay within the cylinder (in 2 microseconds) and the cylinder looks 60cm deep means they must now be going 300,000m/s, or 1000 times slower than light at that point. The scintillator can’t be used to measure the original speed, only the slowed-down speed. So the real question is how is the original 0.995 **c** speed determined? The muon strikes the iron with a certain amount of kinetic energy. As it passes through, this energy gets steadily converted to potential energy according to the equation:- Energy(potential) = force \* distance If the muon comes to a stop, this means the original kinetic energy of the muon has been fully converted. Kinetic energy is given by the equation:- E(kinetic) = ½ mass \* velocity^2 If the stopping distance is known, the initial velocity can be determined. IE how fast the muon was going when it hit the iron. The ½ m v^2 equation however is for classical mechanics. There is another equation that is used in relativity. It is:- E – E0 = m \*c^2 – m0 \* c^2 What is the difference between these two equations? For low velocities there is basically no difference. But for high velocities, the velocity calculated by the classical formula can allow **v** \> **c**. Whereas the relativistic formula ensures **v** \< **c**. The assumption therefore is that the muons entering the iron block are travelling at less than light speed, so ensuring that the final answer is also less than lightspeed. ---
**Author:** ![tomh4040](https://avatars.discourse-cdn.com/v4/letter/t/ee7513/32.png) [@tomh4040](https://boards.straightdope.com/u/tomh4040)\ **Post date:** [November 4, 2021, 11:40am UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/270 "2021-11-04T11:40:58Z")
Czarcasm, they may think that they are not lying as they have been conditioned to accept this theory and blindly repeat it. I did the same many years ago. ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [November 4, 2021, 11:42am UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/271 "2021-11-04T11:42:58Z")
I don’t know what experiment you’re talking about, but I never mentioned muons coming down through the atmosphere. I mentioned particles moving through particle accelerators at known speeds, well below light speed. So, please answer the question posed, not the question you would like to answer. Thanks! ---
**Author:** ![tomh4040](https://avatars.discourse-cdn.com/v4/letter/t/ee7513/32.png) [@tomh4040](https://boards.straightdope.com/u/tomh4040)\ **Post date:** [November 4, 2021, 12:03pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/272 "2021-11-04T12:03:30Z")
Mangetout, your answer is clearly wrong. The clocks do not have to be compared by a third imaginary reference frame (or a real one), and both clocks do not have to be seen at once. I have never used this “privileged reference frame” which you have conjured up. There is a mechanism for comparing the clocks, it is called the Lorentz transformation. Using that transformation, you will discover that used from clock A’s frame, clock A is faster than clock B (and therefore clock B is slower than clock A), and used from clock B’s frame, that clock B is faster than clock A (and therefore clock A is slower than clock B). QED. ---
**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:** [November 4, 2021, 12:09pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/273 "2021-11-04T12:09:59Z")
> [@tomh4040](#): > > The point you (all) seem to be missing is that I am not a relativist. No, no, I think we got that. But does this mean you’re demanding a description of relativity that makes sense in an absolute universe? Because if so, there’s the problem. ---
**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:** [November 4, 2021, 12:11pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/274 "2021-11-04T12:11:21Z")
R…ight. And so when you are present in clock A’s reference frame, there is no contradictory observation from clock B **because you are not also there** ---
**Author:** ![Cheesesteak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cheesesteak/32/3694_2.png) [@Cheesesteak](https://boards.straightdope.com/u/Cheesesteak)\ **Post date:** [November 4, 2021, 12:18pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/275 "2021-11-04T12:18:31Z")
No observer in the universe is able to observe a contradiction, because no observer can inhabit more than one reference frame simultaneously. ---
**Author:** ![k9bfriender](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/k9bfriender/32/3283_2.png) [@k9bfriender](https://boards.straightdope.com/u/k9bfriender)\ **Post date:** [November 4, 2021, 12:26pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/276 "2021-11-04T12:26:35Z")
Why, sometimes I’ve observed as many as six contradictions before breakfast. ---
**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:** [November 4, 2021, 12:27pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/277 "2021-11-04T12:27:52Z")
I prefer to eat six completely consistent breakfasts ---
**Author:** ![Frodo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frodo/32/302_2.png) [@Frodo](https://boards.straightdope.com/u/Frodo)\ **Post date:** [November 4, 2021, 12:52pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/278 "2021-11-04T12:52:06Z")
You have invented 3 new breakfasts! Until now we only had Breakfast, Second Breakfast and Elevensies, forget about this relativity thingie, THAT’s a mind blowing discovery!. ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [November 4, 2021, 2:05pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/279 "2021-11-04T14:05:27Z")
> [@tomh4040](#): > > In real life clock A cannot run faster than clock B while clock B runs faster than clock A. Yes it can. You have given no evidence to the claim that it cannot other than your own incredulity. ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [November 4, 2021, 2:12pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/280 "2021-11-04T14:12:35Z")
> [@Babale](#): > > You have given no evidence to the claim that it cannot other than your own incredulity. But you must admit, argument by incredulity is rather commonly used. Surely, there must be something to it. I cannot accept it does not. It simply doesn’t stand to reason so many people would employ incredulity without some empirical evidence or examples to back it. So you must be wrong about this. 😉 ---
**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:** [November 4, 2021, 2:13pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/281 "2021-11-04T14:13:23Z")
> [@tomh4040](#): > > Mangetout, your answer is clearly wrong. The clocks do not have to be compared by a third imaginary reference frame (or a real one), and both clocks do not have to be seen at once. I have never used this “privileged reference frame” which you have conjured up. **There is a mechanism for comparing the clocks** , it is called the Lorentz transformation. Using that transformation, you will discover that used from clock A’s frame, clock A is faster than clock B (and therefore clock B is slower than clock A), and used from clock B’s frame, that clock B is faster than clock A (and therefore clock A is slower than clock B). QED. In what reference frame are you making this comparison? Be specific. ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [November 4, 2021, 2:54pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/282 "2021-11-04T14:54:09Z")
> [@Great\_Antibob](#): > > > [@Babale](#): > > > > You have given no evidence to the claim that it cannot other than your own incredulity. > > But you must admit, argument by incredulity is rather commonly used. Surely, there must be something to it. Argument by Incredulity is a fallacy, and now you are using Appeal to Popularity - another fallacy - to justify it? Yo dawg, I heard you like fallacies, so I put a fallacy in your fallacy so you can fallacy while you fallacy. [![](https://imgflip.com/s/meme/Yo-Dawg-Heard-You.jpg) ](https://imgflip.com/s/meme/Yo-Dawg-Heard-You.jpg) ---
**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:** [November 4, 2021, 2:54pm UTC](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057/283 "2021-11-04T14:54:18Z")
> [@naita](#): > > Since I did open this line of discussion by mentioning your previous website plug in the thread I’ll spare everyone the labor and show an example of where you go wrong and pick apart the first obvious error that stands out to me, I’m sure it will not surprise anyone in this thread that it has to do with not grasping the concept of reference frames. > > > Einstein uses lightning strikes at two places on the railway track, and says that although they can be said to be simultaneous as judged from the embankment at a vantage point exactly equidistant from them, when judged from the moving train, they are not. He uses this as an argument for there being a different time in moving frames of rerefence. > > I have difficulty in accepting this argument for the following reasons. In judging whether the lightning strikes are simultaneous, he uses light itself as a medium for carrying the information to the observer, without making any correction for the known finite velocity of light. Any number of other observers on the embankment, who are positioned so as not to be equidistant from the two lightning strikes, see the same two lightning strikes, but do not observe them to be simultaneous, and indeed, observe the timing difference between them to vary depending on where on the frame they are. This leads us to the conclusion that there can be an infinite number of time scales within one frame of reference - a conclusion which is not in accord with reality. Guys! Guys. Tom thinks Einstein doesn’t even understand simultaneity in a single Newtonian reference frame. You can keep repeating “two reference frames!” at him in a chorus for 10 times the posts you have so far, and it will make no difference. [Previous page](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057.md?page=13) [Next page](https://boards.straightdope.com/t/can-one-theoretically-travel-faster-than-light-relativistically/950057.md?page=15)