I had my mind blown tonight. It literally exploded. It was messy. You wouldn't have wanted to be there.
I discovered that scientists have sent photons back in time and have proven time travel works for quite a few years now.
What the....?
I also discovered that it seems that the photons can only travel back in time if they're not going back to kill themselves.
Or, to put it another way, it's been proven impossible to go back and kill your father before you were born. They've proven this.
If they send a photon back in time, it works. But if they send a photon back in time to kill itself before it goes back in time, then they just can't send it back in time. It doesn't work.
One of the theories as to why is that the universe has a self-defence mechanism to protect such things.
Another theory is that there's no Multiple Universes, and that there's just one universe that doesn't allow you to go back in time to do anything that prevents your own existence before you go back in time...
What blew my mind was that they're engaging in time travel.
Just... wow.
The second thing that blew my mind was that the multiple universe theory has been disproven.
You see, if there were multiple universes, then you could go back in time and kill your father before you were conceived, which would split your reality off into another universe where you never existed. You'd now be following a different timeline.
In this new timeline, if you tried to go forward in time to where you started this process, then you'd find yourself in a time where you never existed. No one would know you.
It's a theory that tried to overcome the paradox of going back in time to prevent your own existence, meaning you wouldn't be able to go back in time - unless the action created an alternative timeline where you were never born, but also where you could never return to your own universe.
So these experiments they've been doing have apparently proven that you can go back in time as long as it's not to prevent your own existence.
Which suggests that if there's any time travel from the future of actual people or material objects that can interact with this reality, that it essentially becomes part of this timeline.
If you go back in time to prevent the birth of Hitler, for example, you wouldn't succeed, because we all know about Hitler. Instead, your incursion into the past would simply become part of the past. Your actions were already there, as part of this timeline.
You might go back to kill Hitler but end up getting killed first, or it might even be that you were the one that caused Hitler to rise to power...
No one knows what will happen. There's lots of conjecture, however. Lots of thoughts about possibilities.
That's how we get all our science fiction stories, where someone thinks about 'what if' and decides to write it down.
What do you think about this?
Wow!
ReplyDeleteSo if I wil travel to the past in the future, it has in fact already happened, which means that my future journey is in fact necessary? That would kind of indicate that there is only one timeline & everything is given.
it's not so much 'necessary', it's more like 'predetermined'. You won't be able to change it.
ReplyDeletewhich makes me wonder about our ability to make choices. If we can't change the outcome of the past or the future, then it means we have no free will. All of our actions have already been determined.
Maybe someone can tell me I'm wrong about this?
No need to worry about that. Free will and determinism are not necessarily incompatible. If you want to know more look up "compatibilism". Or just read this: http://plato.stanford.edu/entries/hume-freewill/
ReplyDeleteHi Alan,
ReplyDeleteI am not sure about the experiments having already been done. However, when I was studying a bit of physics at the ANU, my lecturer was involved in computer simulations of time travel using our current understanding of quantum physics.
What he and his PhD students confirmed (other scientists had done similar simulations previously, so this was further testing - I have a book by a Russian physicist called 'The River of Time' which discusses this) was that it is indeed true that it is not possible to alter the past with time travel.
What they found was that no matter how they set up the experiment they could not alter the past.
They used the notion of a time portal. Basically, they (in the simulator) fired a particle through the portal and attempted to have it emerge back in time to prevent itself going through the portal (for example, by striking it and thus diverting its path). They basically found that no matter what 'angle' they used, the result was not a paradox.
This fits with the notion of block space-time, which is part of Einstein's Theory of Relativity. The thing is, the order in which you see events happen depends on your relative velocity to those events, which is another clue that space-time is 'fixed'.
However, I am not sure if this disproves the many universes theory. In any particular universe, it would appear that there is no paradox. But if you went back in time and killed your grandfather it is possible that you would discover yourself in a universe in which you existed back in your grandfather's day (you killed him, after all) but had not been born in the future of that universe - I am not sure.
However, I have other doubts about the many-universe theory, so I am not going to defend it too vigorously here.
As to free will, we have no free will. But why would we want to have free will?
I thought that I would add something about the order of events issue in relativity.
ReplyDeleteThe common example used is that of a person standing in the exact centre of a train carriage that is sitting completely still.
Each end of the train carriage is struck by lightning. In this example, from the person's perspective, it appears that the lightning strikes occurred simultaneously.
Now imagine a second train carrage coming along a track adjacent to the train carriage. In that carriage, there is also a person standing in the exact centre.
At the instant that the lightning strikes our original carriage, the two carriages are right next to one another. The person in the second carriage is moving away from the point of impact of one of the lightning strikes and moving towards the point of impact of the other. If the speed of light was infinite, he too would see the strikes as simultaneous. But it is not. Thus, the distance that the light from each strike travels to reach him will be different - shorter in the case of the point that he is moving towards and further in the case of the point that he is moving away from. Thus, from his perspective the one he is moving towards will appear to strike first.
Now think of yet a third carriage. This one is coming along a third track in the opposite direction. If at the instant of the lightning strike it too is right next to our first carriage the person in it will have the same experience as the person in the second carriage, except that they will see the strikes occurring in the opposite order (the one that they are moving towards will seem to occur first, and this is the one that will appear to occur last to the person moving away from it.)
So: did the lightning strikes occur simultaneously, in the order the second person saw them occur or in the order that the third person saw them occur?
The answer is that the order of events depends on the reference frame of the observer. There is no fixed 'order of events' in an Einsteinian universe as there is no special frame of reference. And this is a direct consequence of there being a speed limit on how fast light can travel. Newton believed that there was no speed limit and thus in a Newtonian universe there is indeed a special frame of reference that determines the order of events. But Newton was wrong in this regard.
It should be pointed out that because of the speed of light limit you could not (for example) witness someone being shot before the bullet was fired and be able to warn the person to get out of the way. Your warning would not reach them before the bullet was fired. This is more evidence that there is no way to alter the past and that it is indeed fixed: block space-time.
For information: my physics study was about 12 years ago, so a lot of work has likely been done on this since.
ReplyDeleteHaving done a bit of research, yes, they have done experiments along these lines. It should be pointed out that it is a little tricky to compare what we might think of as time travel with the quantum time travel discussed by physicists. But it matches the simulations and seems to prevent paradoxes. Again, I am not quite sure why it rules out the many universes explanation for quantum mechanical effects.
ReplyDeleteI would think that if 'multiple universes' theory was true, then you could still send a photon back in time to kill itself before it can go back in time. The fact that it didn't seem to work would indicate that of course it didn't work for you, because you were able to send it back in time. But you know it should have worked because the accuracy is true. Therefore, its death must have occurred in another timeline instead. And since you can't send it back to kill itself, but you can send it back for other purposes, then there's only a single unalterable timeline rather than multiple timelines. That's my understanding of it in the context of these experiments.
ReplyDeleteTrue. If you never observe it doing that, then it can never have been sent from another universe. Interesting.
ReplyDeleteAs a hard incompatibilist, I would caution people against taking compatibilism seriously. While I admire Strawson and Dennett, I think that they are misguided. But, having said that, I admit that I do not understand some of their arguments.
ReplyDeletehttp://en.wikipedia.org/wiki/Novikov_self-consist...
ReplyDeleteNovikov is the author of the book that I read, and it is his principle that appears to be what the evidence of simulations and experiments are supporting. Note that I do not think that it has been 'proven'. Nothing is proven in science. We just get more and more evidence.
'All You Zombies' and 'The man who folded himself' are stories about this kind of thing. They are basically about people who travel through time and become their own parents. At the end of 'All You Zombies', the main character thinks, 'I know where I came from but where did all you zombies come from?', basically stating that his existence is perfectly explained - he exists as a closed loop - but that everyone else must come from an infinite regress of causes, which is impossible.
ReplyDeleteHi David, I realize that my comment was not entirely politically correct. The nonchalance with which it was written made the matter seem more clear than it actually is. Basically my position is that our having free will as an objective fact about the universe may well be illusory, but this doesn't make our subjective experience of ourselves as free agents any different. Everything that happened & will happen may well be written in stone, but as for us, we're incapable of ever knowing all the details. Therefore, determinism is not practically applicable to the way we conduct our lives. We must still make choices, even if they are predetermined.
ReplyDeleteHello Tereza,
ReplyDeleteI agree that we have no other way to experience the universe. However, I believe that there are practical (and moral) implications if there is in fact no free will. As an example, I believe that the way in which we deal with criminals needs to be re-evaluated, with the punishment aspect of imprisonment completely removed (for example). This does not mean that we should not lock up those who pose a danger to society (or even kill them, not that I support the death penalty). However, it should mean that imprisonment becomes an overall positive experience for a person, in that rather than damaging them by exposing them to violence and anti-socialisation it protects and teaches them.
From my own perspective, I have found that I am much less judgmental of people since my coming to believe that there was no free will. Environment and genetics shapes ones life. Nazis were the way they were because of their environment - I would likely have been one in such a culture.
"Nazis were the way they were because of their environment - I would likely have been one in such a culture."
ReplyDeleteI always suspected that about you... :)
I hear you David. And I agree to a large extent. I have also found that the contemplation of the possibility of determinism (I'm still too skeptical to call determinism a fact) indeed makes one less judgemental. I'd be cautious of making radical changes to the way society deals with criminals though. Even if they are not responsible for their actions from the objective standpoint, and even though I'm not a believer in the effectiveness of punishment, making imprisonment an overall positive experience would, in my opinion, send the wrong message. It would be somehow unnatural. I still consider some acts evil, even if they were predetermined. Also, not everyone coming from similar external environment becomes a criminal. There seems to be such a thing as "internal" environment, which makes some people more susceptible to becoming criminals under similar external circumstances. You can see being evil / doing evil things as a form of being unlucky. But that doesn't make evil any less evil. I do feel compassion for the Nazis & the criminals. I consider myself lucky to be an overall kind person. If my (external & internal) environment made me into a Nazi or a criminal, I could call it bad luck. I wouldn't expect it to be an overall positive experience though. People ARE supposed to suffer when they harm others, even if it was "bad luck".
ReplyDeleteI have no belief in the existence of evil anymore. There are, however, actions that cause unnecessary suffering, and these are to be avoided and opposed if possible. I think that the notion that people should suffer when they harm others is still stuck in the notion of punishment. People should not be punished. They should be contained to protect others from their actions. They should be educated to change their attitudes if possible. If that is too difficult, it might be necessary to detain them indefinitely. (But in very good conditions).
ReplyDeleteI agree that there is an internal environment. We are not blank slates for the environment to write upon. I used the term 'genetics' for this, but it likely encompasses more than that.
It has been shown that it's natural to suffer faced with suffering of another. (I'm alluding to the "mirror neurons".) By evil I mean actions that cause suffering to others without causing immediate mental suffering & regret within the agent, and the susceptibility towards performing such actions. My notion of evil is not metaphysical.
ReplyDeleteI honestly admire your rational approach, and perhaps society will evolve in this direction, but I'd still prefer to be "stuck in the notion of punishment" than not to be horrified & appalled by evil actions and not to feel the urge to make the agents who perform them suffer. When I see a bastard, you can count on me to punch him in the face & feel good about it. Like I've done the right thing. Perhaps it has to do with my genetics?
I still have those feelings. :)
ReplyDeleteI think it is human nature to have those feelings - we cannot not have them.
And we have no free will about how we act on them, either. ;)
:-)
ReplyDelete