I Tweeted the following inscrutable remark. Probably best left unexplained, but upon reflection I can’t resist.
My consciousness freely travels up and down my world line, but sadly it only carries the memories appropriate to the moment it inhabits.
The point is that (some) people don’t think about the flow of time in the right way, and this leads to a couple of unfortunate consequences: a difficulty in understanding the psychology of time, and a scattering of entertaining but illogical science-fiction scenarios.
Modern physics suggests that we can look at the entire history of the universe as a single four-dimensional thing. That includes our own personal path through it, which defines our world line. This seemingly conflicts with our intuitive idea that we exist at a moment, and move through time. Of course there is no real conflict — just two different ways of looking at the same thing. There is a four-dimensional universe that includes all of our world line, from birth to death, once and for all; and each moment along that world line defines an instantaneous person with the perception that they are growing older, advancing through time.
But if you don’t play too much attention to the way these two views fit together, you are tempted to imagine that “you” might actually, in some set of laws of physics if not actually in our own, go visit different moments in your own life, carrying along the consciousness of your “present” self. Something like that happens in SF stories from Slaughterhouse-Five to Back to the Future. But it’s not consistent — it requires the implicit introduction of a kind of “meta-time” that keeps track of when we visit the ordinary time with which we are familiar. That’s not how nature works; my tweet was trying to point out the inconsistency of taking this idea seriously, subject to the strictures of 140 characters or less. (To be earnestly explicit: if you did manage to travel up and down your world line at will, you would indeed have whatever memories were appropriate to the moment you were inhabiting — which means it would be exactly like not traveling at all.)
Sometimes, unfortunately, people go further than science fiction. I’ve run into folks who believe that our conscious perception of time passing is actually evidence against modern physics — arguing that we need to change the known laws of physics to account for the flow of time. It’s always conceivable, in principle, that what we think we understand at a basic level is completely wrong. But the evidence had better be pretty overwhelming. The brain is a complicated thing, and I don’t think that our present inability to provide a complete and comprehensive theory of conscious perceptions should be held as compelling evidence that the laws of physics are in need of overthrowing.
But a huge unknown, in physics and neuroscience, is consciousness. One or both of these worlds will be overturned when and if consciousness is unravelled. My guess is that both will have major change.
No need to overthrow laws of physics. Just generalize them. Biology and consciousness is something with which the text book physics cannot cope with.
It is of course extremely non-realistic to think that all of relevant physics had been understood five hundred years after Newton. To get some historical perspective it is good to recall that the general belief for about 110 years ago was that classical physics was all that is needed! It would be easy to ridicule these ancient colleagues but our fate might be the same unless we are very very cautious;-).
By analogy, all of the information for a movie exists as a block on a DVD, but my DVD player, like my consciousness, makes it appear to me that the information (scenes) flow through time.
Couldn’t my “future” worldline (that is, the part that my conscious self has not yet remembered), conceivably have some loop-de-loops in it? After all, I don’t yet remember whether my far future self has visited my slightly less far future self. I have no idea what my consciousness would remember at the moment where the loops start to inhabit the same slices of time, but is anything precluding that possibility? Obviously I can’t visit my past self, since I don’t remember having any visitors, but i think that I might be able to visit my future self once he’s become my past self.
@Matti Pitkanen
What’s the basis of this claim? And… you should probably read Sean’s “The Laws Underlying The Physics of Everyday Life Are Completely Understood” Part 1, Part 2, and Part 3 before you answer this question.
Your argument appears to be “in the past people thought they knew some stuff that it turned out they were wrong about, so we’re probably wrong about stuff we know now – and, interestingly, not just any stuff, but this very topic of conversation.” Actual science is hard – you have to know lots of stuff, think about it, do tricky experiments, and all that. If we could reach valid conclusions with just a superficial knowledge of history instead, we would do that. But that doesn’t, you know, work.
Sean, I wonder what the implications of this on discussions of free will/decision making are? If the four-dimensional universe includes our world line are we simply deterministic machines with our consciousnesses providing an “illusion” of the ability to make decision when from the full-dimensional view it is simply following its worldline?
Wow, I think I’m experiencing deja vu. 🙂
Sean–
Your statements hold only classically, assuming the world is deterministic. QM greatly complicates this picture, as you know. Even if you insist on viewing QM as being a deterministic theory of the wave function of the universe, the notion of unique classical worldines existing in a unique classical spacetime geometry doesn’t exist at a fundamental level. For those who follow the Everett interpretation, the insufficieny of unique classical worldlines and unique classical spacetime geometries is even more striking.
“What’s the basis of this claim? And… you should probably read Sean’s “The Laws Underlying The Physics of Everyday Life Are Completely Understood” Part 1, Part 2, and Part 3 before you answer this question”
i read them, they are just his opinion, not scripture put down on the internet.
Wm James explained this sense of time by a ‘specious present’ or 3 second interval that our time-bound self followed. This temporal window flows in the direction of increasing entropy. Outside of this specious present we use memory for both a look back at the past (against the arrow of time toward decreasing entropy) and a memory of the future (faster than increasing entropy is aging us). The look into the future or the guesses about the future hijack the use of memory to reconstruct ‘what must have happened’ and ‘what will happen next’. The extent to which I can make correct guesses (the inevitable shattering of a glass vase dropped to the floor) determines my ‘temporal fitness’.
So it doesn’t matter *how* I guess what *really* and *accurately* happened in the past or what is about to happen next, it only matters that my guess about what happens next is more fit . – it only matters that I make better guesses than the guy next to me. This frees my 4th dimensional self from the chore of ‘carrying along my present self’ when I need to remember a useful (fit) version of the past or future.
Everything is opinion until evidence is presented.
Nobody said anything about scripture but you. Sean explained and supported his claims, rather than tossing off a vague, one-sentence assertion, yet you’re leveling your tedious sardonicism in his direction instead of Matti’s.
The claim was made that consciousness and biology are incompatible with our current knowledge of physics. How so? Where is the “aether” for biology? Where is the “ultraviolet catastrophe” for consciousness?
This is so interesting: Lloyd Rudy, cardiac surgery expert.
Especially because, as he says near the end, his colleague surgeons have had similar experiences with patients. How can a confined biological brain account for this? What is consciousness that allows such veridical cases?
As he says, “he was up there!” (above the operating table). “He described the scene (seeing?), things that there is no way he knew…what does that tell you…is that his soul up there?”
The patient described the operating room accurately and then there is this “presence” staff felt in the second case he described. What was that?
http://www.youtube.com/watch?v=JL1oDuvQR08
Mike @ 9: Of course you’re right that the classical worldline is a fuzzy path at the quantum level. But to my lights, the human notion of the ‘flow of time’ exists at a classical level and not the fundamnetal level, so I think Sean’s basic points still stand.
Sean: “To be earnestly explicit: if you did manage to travel up and down your world line at will, you would indeed have whatever memories were appropriate to the moment you were inhabiting …”
What is your evidence for this assertion?
Sean: “…it requires the implicit introduction of a kind of “meta-time” that keeps track of when we visit the ordinary time with which we are familiar. That’s not how nature works…”
How do you know?
I’m not trying to coy. I just haven’t heard about experiments which have addressed this, one way or the other.
It is amazing to me that we still (in my view) have absolutely no handle on what time actually is. Transforming it into a measure of entropy helps not at all. And saying that time didn’t exist before the Big Bang is even more nonsensical if one bases that view on the Big Bang occuring due to a quantum fluctuation. How does a fluctuation occur without time? At some point no Universe existed. At some point, one did.
Kindly explain.
Any attempt to cut away anything but the present moment would fail, because you are free to expand the current state in any basis. If you apply the time evolution operator to the basis states, you obtain the future states, but by this argument, this then exists also in the present moment.
RE: @12, out-of-body-experiences, operating tables:
There is a semi-scientific study underway in several hospitals in the UK and USA:
http://www.telegraph.co.uk/news/uknews/2980578/Scientists-study-out-of-body-experiences.html
From what I read elsewhere on this study, it has been running for some time and no positive (confirmatory) cases have yet occurred. We should wait for a peer-reviewed report, of course, but my money says that it will be found once again, that the supernatural never occurs in reproducible, double-blind experiments, and that anecdotes aren’t data. After all, eye-witness accounts are often found to be inaccurate in criminal trials when people’s lives or liberties are at stake. Why trust them when they contradict all that is known in science?
@16 – IANAP, but I think there is a distinction between time in our universe and time in some other universe from which a quantum fluctuation may have seeded ours. Time is relative within our universe, and General Relativity says that time stops (does not flow) within a black hole, so if our universe started at such a singularity, there is no physical way to get through it to experience time on the other side (prior). Nonsense? Well, but GPS devices don’t work accurately unless GR theory is used in their calculations, and there are many other experimental confirmations.
“Biology and consciousness is something with which the text book physics cannot cope with.”
What’s the basis of this claim?
i looked for both terms in my physics text and they are not there
@18
Updates will be here: http://www.horizonresearch.org/ the main site for this scientific study.
Of course the first case above by Lloyd Rudy wasn’t just anecdote but confirmed, it seems – he was on the spot during this and knew the sensory capabilities of his patient – around zero?
And what does one do with the second case – an apparent healing? Dump the data?
If the “anecdotes” keep coming like this, then eventually with this kind of subjective data you’re going to be raising your confidence levels. My money is the other way – I think Nature will surprise!
Maybe the solution is somewhere in the physics – a la Feynman and the “qualitative content of equations”?
Barring the presence of mental illness, i have noticed, now in my near dotage years, that my own memories of the long past have been reframed in a much more positive tone. Blessed be the elder status.
As an avid reader and a most interested layman I offer my first comment. If God ( or whoever bestows mathematical ability) had been most kind I would have been a Physicist/Cosmologist. Sadly that was not the case so I merely observe and often ponder the deep mysteries of the universe and our existence. Time/Gravity to the layman are still mostly unanswered questions from an explanation in a common language perspective. Einstein changed the way that we can consider space/time. Massive bodies warp space/time.
Ok easy enough to follow .. but then how do you get from there to the proposed graviton ( search still continues for this force (sic) carrying particle ). Or is Geometry enough to carry the day however complex (point particle being a geometric object).
Back to the subject at hand… just a thought who is the I that i speak with in my thoughts and dreams. Tough to answer.
Jeff
But the particles that make you up are constantly being replaced over time. How do you square that with the world line idea?
#18: I have no problem with GR (aside from the fact that it is incompatible with QM) and as you say, time does stop at the event horizon of a black hole, but I don’t see what this has to do with the current discussion. As to your idea that our Universe was spawned from another Universe which already had Time, that in my view is like an argument for God, i.e. ad infinitum.
Hi Jens,
“It is amazing to me that we still (in my view) have absolutely no handle on what time actually is.”
I think some people do. Indeed, I think Einstein (at least late in his life) was one of them.
“How does a fluctuation occur without time?”
I think that’s a perfectly valid question. If the so-called quantum vacuum before the big bang is said to not be in time, it can’t be said to have caused, or be causally connected to, the big bang. If it is, one is faced with the contradiction of an infinite past.
Best wishes
Peter