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WorldWeird: Chinese Physicists Prove Time Travel Impossible
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Didn't Einstein theorize that time isn't linear, but that our perceptions shape it that way? Could you hack a human brain to turn this off and add enough extra processing/storage capabilities so you don't go mad?
This would effectively let you time travel within your lifetime. Combined with life extension techniques you could theoretically experience all of the rest of time, until the heat death of the universe. I imagine a lot of people will choose to stay in that one perfect moment of their life forever, but with an infinite amount of time to think maybe someone will even come up with a way to survive that.
I have to say that hollywood style time travel seems completely irresponsible and I wouldn't trust anyone that was willing to do it. -
"Theorising that one could time travel within one's own lifetime..."
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Human perception of time is already non constant. Experiements show that younger people perceive time passing more slowly than older people do. And that fear can massively stretch out the passage of time (excellent experiment for the latter, asking people to attempt to count to 10 seconds whilst bungie jumping...)
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- CommentAuthorsellmeyoursoul
- CommentTimeAug 9th 2011
I can confirm that fear stretches the perception of time... While upside down at 72Mph (with the sun roof open), I have total recall of the cracks growing like ice crystals across the windshield (and thinking that would be the last thing I ever saw, even if I didn't get killed in the crash). That was almost 20 years ago. Although, I'd theorize that it's probably more a bio-chemical "notice every fucking detail until you can figure out the one that will allow you to not be quite as dead as otherwise" sort of a thing than some sort of quantum space-time effect. -
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CommentAuthorArtenshiur
- CommentTimeAug 9th 2011
@John Skylar: No, actually, because anything that places those restrictions will be an observation, collapsing the wavefunction and ending the "transmissive stage" of the entanglement. It's taking the cat out of the box and shooting it. -
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CommentAuthorJohn Skylar
- CommentTimeAug 9th 2011
@Artenshiur Creating a potential well that spans the space a particle may occupy is an observation? We have to talk about this elsewhere, because it's gonna take over the thread entirely, but I think if the answer to that question is "yes," a man named Griffiths has a lot of explaining to do regarding his quantum mechanics textbook. -
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Didn't Einstein theorize that time isn't linear, but that our perceptions shape it that way?
Not as far as I know. In fact, it's important to Einsteinian relativity that we see the universe as 4D spacetime, not just 3D space. Time being a dimension seems contrary to it being a perceptual artefact.
Don't know where this idea of time being subjective comes from, but people (outside the sciences) seem to bring it up quite a lot. I guess there is the fact that sometimes it feels as if time is moving faster or slower, but there's a really big leap to saying that time itself is imaginary. When I discover that something was bigger than I thought it seems reasonable that my perception was wrong and not that, I dunno, width is imaginary. -
It's not so much that your perception is wrong, just that your ability to measure time is a function of your brains current 'clock speed' (to use a crappy computing analogy) and that certain chemical changes can affect that. Adrenalin speeds you up, so your perception of time slows down etc...
Sensory perception as a whole is a fun one to experiement with, it's very easy to proove for example that everyone has a unique pattern of audio frequencies that they can't hear. Which means that what I sound like to myself isn't what I sound like to anyone else at all. This extrapolates out through sight (colour blindness, for example) and across all the other human senses (phantom limb syndrome, synaesthesia and so on...)
Our ability to perceive anything at all is very personal and unique, and changes during the course of our lives.
In terms of raw science, a second is a second and pretty much immutable. It's just that what feels like a second can vary to us. -
That said, time can be a bit... flexible. There are relativistic time distortions from travelling at very high speeds, and it runs slower near big masses.
You can verify this experimentally on Earth, if you happen to have two atomic clocks. Synchronise them at sea level, then take one to the top of a mountain (further away from the mass of the Earth's core). Leave it there for a few weeks, then bring it down. The clock that stayed at home will be a teeny tiny bit behind the clock that went on holiday.
Of course, you can't perceive that time runs slower closer to huge masses because everything runs slower including your brain and your perceptions.
And, interestingly, the two places (that I can think of) where we see time being distorted, we also see spatial dimensions being distorted: Lorentz contraction when moving at relativistic speeds, and gravity - the effect of mass on space. -
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CommentAuthorArtenshiur
- CommentTimeAug 10th 2011 edited
@John Skylar, looks like you're right. I couldn't remember the name of the theorem, but I found it (and felt stupid, because it is the no-communication theorem) and it doesn't fully disallow communication. But I find it unlikely because superluminal communication necessarily leads to causality paradox. It remains an open question. -
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CommentAuthorBrianMowrey
- CommentTimeAug 10th 2011
Didn't Einstein theorize that time isn't linear, but that our perceptions shape it that way?
Were you maybe thinking of Kurt Vonnegut.. -
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CommentAuthorAlan Tyson
- CommentTimeAug 10th 2011
As I understand it, the whole "time slows down when you're scared/excited/active" thing comes from the fact that your brain is taking in and processing more information, faster, in the same span of time - so its not that you're really noticing time differently, you're just doing more that you usually can within the same span of time. -
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CommentAuthorAriana
- CommentTimeAug 10th 2011
The time perception in a crisis thing is (accepted theoretically) even simpler than any of that. Many people think in terms of "what's going on during a crisis" when they talk about being able to see things moving in crystal-clear slow motion -- but that's not how our brains work. All we ever know is how well we can remember what happened in a crisis.
Small distinction: all the difference.
At any normal time, our brains are processing a shedload of information. Right this very second, you are taking in sounds you're not even bothering to listen to, you're aware of the light in the room, but another part of your brain is actually measuring the levels of light and calculating approximate time. There's an entire server-room full of brain power monitoring biological functions. A part of your brain is reading the words I've typed here, while another part matches the individual words to previous memories. You're smelling things, feeling *everything* including the clothes (or lack of) on your body. If I draw attention to it, you'll notice yourself breathing, or blinking.
At any normal time, you process every little bit of that and *so* much more... and promptly forget it from one second to the next. I mean, come on -- try to imagine remembering every breath you've ever taken in your entire life. Right. Most moments in your life get a twitter status update: "Stuff happened, time passed."
In times of crisis, you process (very likely) the *exact same things*. It's not like your brain swells (except, I suppose, in situations where the crisis *is* your brain swelling) to give you more processing room. What *happens* is that, after the fact, you *remember* more of it because instead of filing everything that happened as "natural as breathing: easily forgotten" your brain assigns emotional impact to the events. Just like you can remember falling in love, or happy childhood events, or the scene of a movie when you got something in your eye, you can remember more of the events during a crisis because your brain files it as "this mattered more than breathing: we were *feeling* so more than usual." Those *big* moments in your life: fear, love, pain, focus -- they get an extended liveblog update. When you look *back* you can remember more than you usually do -- so you think you were seeing more, or time was slower.
In reality, everything was pretty much exactly the same, your heart just flagged the moment as more memorable. -
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CommentAuthorBrianMowrey
- CommentTimeAug 10th 2011 edited
I don't know. While that is true, (it is the same reason probably we experience time as going slower in youh; more of what happens is seen as novel and critical to remember at the time), the remembering effect explains the passive element of crisis slow-mo, not the active effect.
I always ride my bike on the street, because sidewalks get you in trouble. But as I had crossed a street earlier than I meant to, I was heading two blocks on the sidewalk right next to the incoming traffic of Burnet Rd this one time. My bike is a road bike. I was going fast because there was good sidewalk ahead. When I was crossing a side street and saw that the next sidewalk was curbed with no ramp, I was in a shit ton of trouble. Braking takes ten seconds, I had one.
Point being, it's not just that I came to the decision to hop-and-bale on the grass by the sidewalk instantly, sparing my precious wheels, but that I remember waiting for the curb to come after I made that decision, and thinking how weird it is that I'm waiting, because again, this is only a one second window between when I saw the curb and would have hit it.
It's only anecdotal, and we all have false memories, but given how much people tend to be capable of in instant crises, it seems to point to something.
Typed on mobile -
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CommentAuthorAriana
- CommentTimeAug 10th 2011 edited
Haha, many people have absolutely no idea how much of their life is done on autopilot. Bikes are not magical things that balance themselves. Even when you're going really, really fast. Next time you're on your bike, pay really close attention to what you're doing. I mean, *everything* you're doing. Each turn of the pedals. Pay as much attention as you possibly can to the weight of your body, and each tiny little shift of your back, forearms, head, every single muscle you're moving. If you can do that *and* manage to stay upright (and I don't even have to bet it'll be harder than you imagine), then add on paying attention to your breath -- every breath in and out, *while* balancing, while pedaling. And your heartbeat -- you should be able to feel it if you hold your breath on the intake, while balancing, while pedaling. And, just for shits and giggles, pay attention to your surroundings while you do that -- count how many cars/houses/people you've passed.
If you're not dead at this point, having run into the road and in front of an oncoming car, you should have a better idea of the repetitive tasks you've done enough times that your brain can run them without *telling* you about them. At incredible speeds. Supercomputer speeds. All the time.
Jumping on the grass in a second is, really, not that big a deal on top of every other thing you process ever millisecond you're on a bike. What you remember, very likely is that it took a moment for you to consciously, actively think about what you were doing. Just like breathing, pedaling, balancing, seeing cars, all the other things you do all the time and your brain doesn't mark as memorable. The only reason you *do* remember is because of the emotional impact of the moment -- slightly higher than the calm moments beforehand.
How do we (pretty sure) know this? We stuck digital timers on people's wrists, going *just* faster than they could perceive even when they were focusing. The numbers were speeding by at a blur, just like the blades of a ceiling fan, even a little faster so they couldn't catch the numbers even by blinking or shaking their heads. And then we dropped those people from a very high place to make them panic. And while they swear that time went so much slower than usual, they *swear* they had more time to make decisions about how to relax or tense their bodies, they *swear* they could see every second of the ground rushing up to meet them -- they still couldn't see the numbers on those timers. -
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- CommentAuthorFlabyo
- CommentTimeAug 10th 2011
It's ridiculously easy for our brains to take a really complex process and make it subconcious.
I'm a computer programmer, never been taught proper touch typing in my life, but I can type a post like this 6 pints down because the connection between what I want to say, and typing it out, is at a level where I can do it faster than I can actually speak.
I enjoy freaking out my folks by 'air typing' stuff, because I'm past the point where I have to think about where to place my fingers.
But I can't drive. Never taken a lesson. And sitting in a car being driven somewhere by friends scares the shit out of me because there are so many things going on there that they simply don't even need to think about anymore. -
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CommentAuthorBrianMowrey
- CommentTimeAug 10th 2011 edited
Jumping on the grass in a second is, really, not that big a deal on top of every other thing you process ever millisecond you're on a bike.
Oh.
No, I don't do stunts or bale on my bike very often. Usually if I fall it'll be more of a horrible helpless bumbling slide. The curb-bale was a pretty elaborately novel, in that I had to pull up, turn sideways so body goes left, but keep bike moving with me instead of kicking it right, off the sidewalk and under some SUV's tires, meanwhile keep the left arm from getting broken under the sideways me and bike when landing.
I just don't think everything is down to memory. If you look at time perception as an issue of memory, then it looks like memory is behind all of time perception, but it seems that there are at least one or two other things that lead to real quicker thinking going on. Also, the points just made about idle brain activity seem to be blending conscious and unconscious processes a lot. Unconscious processes don't usually add load to our mid or fore-brains, of course -- so I think it's not something that can be portrayed as like passing through the same processor and being forgotten. The hind-brain is handling breathing and heartbeat for us (pons (brainstem)) and probably does the work of typing-without-aiming (cerebellum (guy in the back)) -- that's not really a memory awareness issue I think.
Speaking of the good old cerebellum, that guy is a lot heavier by cell-count (almost 3/4 of our brain's neurons are crammed in there) and obviously a lot faster than our conscious brain (the cerebellum is the supercomputer that keeps me balanced on my bike in habitual scenarios). For unhabitual scenarios, the moment where the car is heading straight for us and we say "that's not right", in that one second of crisis maybe our brain's decision center becomes more blended. When we come up with instinctual physical responses and execute them in time, we are letting our muscle memory give the green light, rather than our verbal "i should do this movement" memory. Maybe that's where the big perceptive difference in thinking speed comes from. We are living for a small second in the faster part of our brain.
On the other hand, that watch test was pretty devious, and convincing.
(PS Flabyo, learning to drive doesn't take as much practice as learning to type without aiming. Required muscle-learning for driving is like 0, you're just sitting and pushing your arms around. The learning curve is all just visual memory, which the brain is very good at as I understand it: it soaks in all the situations and the relevance of every smallest detail when you are starting out, and within three months you can tell at a glance what is going on, really.) -
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CommentAuthorAriana
- CommentTimeAug 10th 2011 edited
If you look at time perception as an issue of memory, then it looks like memory is behind all of time perception.
This is precisely several theories of time perception. To get *incredibly* pedantic, there's not a thing you've ever seen in your entire life that wasn't over a microsecond before the image got from your eye to your brain. To get a little less, but still fairly, pedantic, you need to remember the words at the beginning of this sentence to understand what it said by the time you get to the period. To point: a second is an *awful* lot of time -- 60 bpm is slooooow -- but in order to realize a second of time has *passed* humans need to remember that they started counting a second ago.
(As for mixing processes, well, it's fair to call me on that. My point was more to make you aware of what your squishy head organ does all the time. Smarter folks than me still don't know what all the bits do, anyway. On the other hand, I launched a shark out of a cannon to explain photons, so it's not like you didn't go into my explanation knowing that I mix my metaphors a bit. FOR SCIENCE.) -
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CommentAuthorArtenshiur
- CommentTimeAug 10th 2011
I do recall some evidence for actual perception being improved in stressful situations: do a d' test for numbers flashing quickly on a small screen, just to the point where d' is within error (that is, the person can't tell what numbers are flashing). Then do it again, but just at the beginning of the test, drop the person into freefall. You will reliably get a (comparatively) high d' (that is, they will see what numbers are flashing). Can't find the paper, though. -
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CommentAuthorFinagle
- CommentTimeAug 11th 2011
To point: a second is an *awful* lot of time -- 60 bpm is slooooow -- but in order to realize a second of time has *passed* humans need to remember that they started counting a second ago.
For further reading, Bergson's notion of time as duration may be relevant here. -