Timeline for Is time travel possible?
Current License: CC BY-SA 2.5
20 events
| when toggle format | what | by | license | comment | |
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| Mar 15, 2021 at 6:31 | comment | added | anna v | @Fireburn your question is not withing the mainstream physics frame that is necessary for questions in this site. As my answer says, within mainstream physics there is no ossibility of using the time dimension in the same way as the space dimensions. | |
| Mar 15, 2021 at 2:05 | comment | added | Fireburn | How about this: physics.stackexchange.com/questions/621248/… | |
| May 9, 2013 at 12:33 | comment | added | anna v | @BenCrowell as this was a migrated question from the skeptics.se I answered it in general terms. In the link given at the start of the question there are answers that go into detail, including yours. | |
| May 9, 2013 at 10:44 | comment | added | user4552 | This answer doesn't discuss what physical principles are involved. An answer that simply says "no" is not very useful. | |
| Apr 3, 2011 at 6:57 | comment | added | Marek | @JBSnorro: ah, no problem. The discussion was quite pointless anyway. But I can't resist sometimes :) | |
| Apr 3, 2011 at 0:31 | comment | added | JBSnorro | @Marek, hm, I did mean that. And ok, time-dependent laws would emerge from time independent laws. To conclude this discussion I'll admit I was wrong | |
| Apr 2, 2011 at 19:33 | comment | added | Marek | @JBSnorro: if they change in a predictable manner then there are some deeper laws that describe this change but don't change themselves. Be that as it may, we need some basic laws at the bottom that we can take for granted. / Oh, finally you present some rational argument. Any source for that evidence? I hope you don't mean just the cosmological dependence of alpha which was pretty much settled as flawed experiment. | |
| Apr 2, 2011 at 19:03 | comment | added | JBSnorro | @Marek: If the laws of physics change over time, that doesn't mean you can't predict anything. You can still try to figure out how the laws change, and make predictions based on that. Surely I don't expect the laws to be timedependent, but they might be. There's evidence suggesting the fundamental constants such as alpha have changed over time.... | |
| Apr 2, 2011 at 14:17 | comment | added | Marek | @JBSnorro: none of those failed assumptions have anything to do with basic logic. This one does. Just think about it: if the laws are changing with time, what use is trying to predict something about future? You have no guarantee that your calculations aren't completely useless because the rules of the game changed, so what's the point of doing physics at all in such a world? | |
| Apr 2, 2011 at 13:56 | comment | added | JBSnorro | @Marek: If our universe has laws which do change with time, there can still be science. Perhaps those laws are changing very slowly, then the accurate data we've gathered over the past century only provides a snapshot of that change. You think of time-independence of laws as unquestionable, because your intuitions tells you so, but over a century ago the most prominent physicists didn't question determinism, or that particles and waves are different forms of the same underlying thing, etc. Those were abandoned. You should also try to keep an open mind to relax other unquestionabilities. | |
| Apr 2, 2011 at 2:25 | comment | added | Marek | @JBSnorro: once again, this isn't about intuition, it's about basic logic (predicting future from the past). Once you abandon that, you have no science. I am not going to argue with you as you presented no argument yet, just some blabbering. You face it, our present understanding of the world stands upon few unquestionable assumptions, such as "verification by experiment" and "time independence of laws" and it is these that define science. Weakening these assumptions inevitably leads to loss of predictability and is basically equivalent to religion. | |
| Apr 2, 2011 at 1:34 | comment | added | JBSnorro | @Marek, no then the physics would be something else, not the physics of which our simple human intuition says "it feels right". Face it, our intuition sucks in a lot of scenarios. This is a common cause for the fenomenon "wishful data interpretation" | |
| Mar 31, 2011 at 23:44 | comment | added | Jonathan. | What if we could spontaneously construct a mirror millions Of light years away, and we able to zoom and focus on the mirror sO much you could earth in it. Surely that image of earth will be the distance to the mirror doubled (in light years) doubled in the past? So isn't that transmitting information across time or something? | |
| Mar 31, 2011 at 23:05 | comment | added | Marek | @JBSnorro, that isn't just an intuitive argument. The physics works only because we believe that laws that hold today will also hold tomorrow. That's the fundamental assumption (otherwise you might abandon science altogether and become a prophet of some major religion) that makes physics useful. So allowing time travel (in the naive sense of being able of modifying past) makes physics useless as you wouldn't be able to predict anything anymore. | |
| Mar 31, 2011 at 20:11 | comment | added | Lagerbaer | Note that in a deterministic universe, the grandfather-paradox (i.e. what happens if you kill your own grandfather before your father was born) is not a problem: The fact that you live now proves that at no point in the future will someone travel back in time to kill your grandfather. | |
| Mar 31, 2011 at 19:21 | comment | added | JBSnorro | @Marek. "That it shouldn't be possible" is just an intuitive argument, which are worthless nowadays(relativity and indeterminism etc), though probably correct... But perhaps there's some more abstract version of consistency in which time travel is possible, though unlikely. "Consistency" as we know it, is also just a human concept. I'm just saying.... | |
| Mar 31, 2011 at 15:38 | comment | added | anna v | @Jonathan If that were the case, that humanity could find out time travel in the future , the theories that would allow that would be perpendicular to what we have now. It might be that a bubble which could observe but be on a slightly different world track could do it .The many world theories might come in useful. But all this is science fiction. Fun, but not an answer to the question. | |
| Mar 31, 2011 at 15:16 | comment | added | Marek | @Jonathan: well, that's pretty much why time travel in this naive sense shouldn't be possible: it leads to inconsistencies and the physics as we know it (i.e. science that can be used to predict something about the future) would become completely useless. | |
| Mar 31, 2011 at 14:49 | comment | added | Jonathan. | If someone were to travel back from the future surely it would have consequences, so maybe in the future we determine it is possible, but noone does it because if you step on a fly it could lead to someone not doing of malaria (or etc) and then in the future you have an extra thousand people descanding from that person, etc. Or worse scientists travel to before humans and accidentally destroy the human race. | |
| Mar 31, 2011 at 14:03 | history | answered | anna v | CC BY-SA 2.5 |