Quantum dynamics-rethinking time travel paradox
Rod_Torfulson
464 Posts
By Julianna Kettlewell Science Reporter BBC News6-18-5 If you went back in time and met your teenage parents, you could not split them up and prevent your birth - even if you wanted to, a new quantum model has stated. Researchers speculate that time travel can occur within a kind of feedback loop where backwards movement is possible, but only in a way that is "complementary" to the present. In other words, you can pop back in time and have a look around, but you cannot do anything that will alter the present you left behind. The new model, which uses the laws of quantum mechanics, gets rid of the famous paradox surrounding time travel. Paradox explained Although the laws of physics seem to permit temporal gymnastics, the concept is laden with uncomfortable contradictions. The main headache stems from the idea that if you went back in time you could, theoretically, do something to change the present; and that possibility messes up the whole theory of time travel. Clearly, the present never is changed by mischievous time-travellers: people don't suddenly fade into the ether because a rerun of events has prevented their births - that much is obvious. So either time travel is not possible, or something is actually acting to prevent any backward movement from changing the present. For most of us, the former option might seem most likely, but Einstein's general theory of relativity leads some physicists to suspect the latter. According to Einstein, space-time can curve back on itself, theoretically allowing travellers to double back and meet younger versions of themselves. And now a team of physicists from the US and Austria says this situation can only be the case if there are physical constraints acting to protect the present from changes in the past. Weird laws The researchers say these constraints exist because of the weird laws of quantum mechanics even though, traditionally, they don't account for a backwards movement in time. Quantum behaviour is governed by probabilities. Before something has actually been observed, there are a number of possibilities regarding its state. But once its state has been measured those possibilities shrink to one - uncertainty is eliminated. So, if you know the present, you cannot change it. If, for example, you know your father is alive today, the laws of the quantum universe state that there is no possibility of him being killed in the past. It is as if, in some strange way, the present takes account of all the possible routes back into the past and, because your father is certainly alive, none of the routes back can possibly lead to his death. "Quantum mechanics distinguishes between something that might happen and something that did happen," Professor Dan Greenberger, of the City University of New York, US, told the BBC News website. "If we don't know your father is alive right now - if there is only a 90% chance that he is alive right now, then there is a chance that you can go back and kill him. "But if you know he is alive, there is no chance you can kill him." In other words, even if you take a trip back in time with the specific intention of killing your father, so long as you know he is happily sitting in his chair when you leave him in the present, you can be sure that something will prevent you from murdering him in the past. It is as if it has already happened. "You go back to kill your father, but you'd arrive after he'd left the room, you wouldn't find him, or you'd change your mind," said Professor Greenberger. "You wouldn't be able to kill him because the very fact that he is alive today is going to conspire against you so that you'll never end up taking that path leads you to killing him." ?? BBC MMV
Comments
MIND BENDING!
Also Stephen Hawking has given a good reason why time travel is probably not possible -- if it were wouldn't we be visited by futre humans travelling back in time? Not totally locked down, but a thought. Also there are sub atomic particles, I forget the name (tachon??) but they travel backwards in time. They have been predicted to exist in the earth's atmosphere where they are energized by solar winds bouncing off the atmosphere.
Hell of a fathers day post.
It makes sense that travel to the past is also possible.
Dan
I don't think that's a very good reason... For one, time travlers may be intelligent enough to employ a type of "prime directive", in not interferring, like the Star Trek policy in dealing with less evolved life-forms.
Or, it could be the case that some time travelers have shown themselves, only to be scoffed at. I remember awhile back, there was a guy on the internet claiming to be from the future... Hey came back to get some vintage computer component. Anyhow, dude had pics of his time machine, along with very realistic govt. manual cutaway schematics of the same device as seen in the photographs... I'll try to find pics, but it looked like that ghost catcher in ghostbusters, and was basically a box that contained and/or caused a tiny singularity.
Anyhow, I have a time machine in my bedroom... but you have to wear this leather mask, and these biker shorts in order for it work...
Peace...
FNM
check the pics of the machine...:
http://johntitor.strategicbrains.com/TimeMachine.cfm
check where the pen laser is being bent by the singularity that is in the car with John...
Anyhow, here's the entire story... frucking crazy shit:
http://johntitor.strategicbrains.com/
Yea, but the guy says we'd be in the middle of a cival war by now. Plus, no bike tires by 2008?
Nah. Any responsible person would travel back for observation, not to try to change the past. That's the main rule of ... whatever you call observatory scientists - alter nothing. Besides, even if someone from the future did come back and said they were from the future, they're probably in an asylum anyway.
Plus, if you get too much further into the future, it will be impossible to operate without a social security #, credit card, or some other form of id.
HAHAHAHA
I was believing this guy until he got to the Cern part, because I dont think they did what he says they did. You can never know though. The problem with the spinning singularity idea is that as far as I know, it would take an incredible amount of energy to keep one open for any amount of time. I'm talking the energy of our entire galaxy.
I take back what I said Stephen Hawking said, as soon as I typed it I knew it was a weak argument.
If you are talking about CERN recreating a singularity in a laboratory setting, I believe it happened right on schedule, as fortold by "John".
I thought I had read they had done it, but all I could find now was articles saying they were on the verge of doing it:
http://www.csmonitor.com/2003/0523/p25s02-stss.html
"Amazingly, scientists are becoming increasingly confident that they will be able to create black holes on demand, in quantity, using the new atom-smashers due to come online in the next five years. Some estimates suggest that the new Large Hadron Collider (LHC) at the European Center for Nuclear Research (CERN -the acronym is in French) will be able to create an average of one black hole each second. LHC will bombard protons and antiprotons together with such a force that the collision will create temperatures and energy densities not seen since the first trillionth of a second after the Big Bang. This should be enough to pop off numerous tiny black holes, with masses of just a few hundred protons. Black holes of this size will evaporate almost instantly, their existence detectable only by dying bursts of Hawking radiation."
Article is from 2003. They were estimating within 5 years.
AND... If you understand the manner in which information is growing in multiples of itself, you realize that alot can happy or change, within 20 years. Look at what has happened in the last 100. Anyhow, if they were this close 5 years ago, they will probably be further than they thought within 10.
Peace...
FNM
(continued)
"CERN has already been contracted by Home Depot to sell up to 40% of the black holes produced to the home construction giant. Anticipating a great demand when combined with such items as trash compactors and garbage disposals, spokesman John Jones said, 'This revolutionizes garbage disposal. These black holes will be the garbage can of the future. It will also revolutionize the disposal of murdered government informants. With our Hoffa(tm) line of black holes, gone are the days of concrete shoes and pig farms. When police come looking for the dead hookers, you can rest assured they will never be found in your Home Depot black hole.'"
"On a side note, CERN was approached by Wal-Mart to attempt to secure an early contract for black hole production. However, Wal-Mart management concluded that CERN could not produce the black holes cheaply enough, and opted for a Chinese competitor instead."
Man where do you think these guys come from?
They aren't aliens, they're evolved humans from the future. We'll all look like that in 100,000 years.
So icey, yet so not a good look. Now that's what I call a paradox.
The Past and the Future are in a permanent state of interdependence, locked into an endless dance, like a snake finding nourishment in its own tail, or like
an infantile retard staring at an M.C. Escher painting.
Humans who would presume to tamper with the dance reveal their souls
as oily and their methods as dry, and have about as much effect on the
continuum as a mosquito landing on the label an Lp while it plays.
In other words, humans put the "terd" back in "interdependence".
wow
on the topic of time travel metaphysics, y'all should check this book out
i just took an entire class about it. spacetime worms, the pardox of coincidence solved, the existence of scattered objects, all kinds of crazy shit. there's a chapter on time travel. recommended if you're into heavy and useless metaphysics.
100,000 years? I see that guy all the time...
You know what's funny is that people always assume aliens will be our same size. They could be really small or really huge - although bigger is more likely if Earth studies are true. They say the larger the brain the smarter the animal... so if there was, say, a solid planet with an atmosphere conducive to life that was the size of Jupiter, aliens could be the size of the Empire State building.
That would be some anal probe, though.
what was the class called and where did you take it?
Maybe they're travelling back to our time 24/7, but there's some Kozmic weirdness that prevents them from interacting with our timeline at all. We can't see them, they can't mess with the past....
Because humans are good at doing the right logical thing. Like nobody would every do weird experiments on on willing population. Or release something into the enviorment before they know the effects. That is why geneticly modified crops will not be available for another 30 years.
Have you ever noticed that on Star Trek they ALWAYS interfer with "less evolved" life forms. But of course that is fiction, real scientists would never do something like that.
Tip to time travelers, keep it on the qt or you'll end up in the looney bin.
Dan
Tachyons.
See here: http://physics.gmu.edu/~e-physics/bob/tachyons.htm
it was "Time, Parthood, and Identity" and I took it at UC Santa Cruz. Philosophy department.
But what fun would that be?
It would only be fun if you were invisible but could still fuck with people.
Um, I could think of any number of things to contradict the above statement. President Clinton even publicly, albeit quietly, apologized for our history of secret human experiments, which he described as being in the thousands. I don't know, perhaps you were just being sarcastic and I'm misinterpreting. whatever.
Please to note the next sentence.