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.
Pingback: Time: a glacier, not a stream « Essays and Miscellania
A few comments. First, Pirsig notes in the foreword (or afterword, depending on the edition, though the earliest editions had neither) to Zen and the Art of Motorcycle Maintenance that most people think of their journey through time like they think of walking down the street: they are moving and they are looking toward the future. Pirsig says that the ancient Greek concept of time is much more accurate: we are standing still and time moves past us (we can’t influence its speed) and we are looking toward the past. This is a much, much better metaphor.
I recommend of course The End of Eternity by Asimov, which is actually a spoof of time-travel stories in that it uses all the cliches and really goes over the top—but ends up being one of the best time-travel stories of all time. (In this respect, it is similar to Jethro Tull’s truly excellent Thick as a Brick which is a spoof on 1970s concept albums but actually turns out to be better, by their own criteria, than the things it spoofs.)
There is a very interesting book which reviews time travel in science fiction and in science by someone who knows about both: http://books.google.com/books/about/Time_machines.html?id=39KQY1FnSfkC Recommended almost as highly as Zen… and …Brick.
Dear Mac #40,
That people of science are not humble is among the most laughable of misconceptions. They are indeed the most humble simply by virtue of the fact that they – like no other group of human beings – agree that pictures about the way the universe is must be grounded in the most stringent experimental constraints and logical consistency. It is these constraints then, and not the feeble mechanisms of the mind, that legitimize the method and reflect the humility of its practicioners. Our planet is still a haven for explanations about our origins involving six days, and postmortem scenarios invoking flush gardens soaked in optical light. Scientists are hard to come by. Please go bother someone else.
Hi #52 Phillip Helbig,
Great references, thanks! I think I may have read The End of Eternity once, but if so it was so long ago that I recall nothing at all about it. In a different series I do like the scene of Marvin pacing on that moon literally until the end of eternity in the HHGTTG series, when his time-traveling friends finally bother to pick him up. Somehow it feels like I’ve had friends like that… or maybe it’s just that I’ve been a friend like that? Like the time my brother called me after arriving at the airport, while I was a hundred miles away picking up my son? A bit of time travel would have come in sooo handy that time… 🙂
My simple questions meant for Sean have not been addressed. Is it time to threaten? Perhaps threaten viral? I don’t think so.
I just would like a reply to my very simple questions.
@CTC (35.) Awesome. Short and sweet.
@Alan (38.) Having first-hand NDE experience I’ll explain something in short that probably nobody has. Your body floats up… no. We know that the subconscious does tons of work 24/7 in the background. Processing information, accessing memories, imagining what’s out of view, and so on. When the experience occurs synapses misfire due to lack of oxygen, blood flow or whatever, and you’re practically wired into it on a conscious level. It’s overwhelming. You can’t tell what’s a memory, real or a dream. “Vivid dreaming” comes to mind but a jumble of many at the same time even after you wake up. People halucinate (see/hear) ghosts from their past talking to them, spirits, the operating room, heaven, all kinds of stories. Keep in mind that all accounts are after the fact and the effects can take days, weeks, months to fade if ever and the stories are after the fact. So basically all the stories can be explained as situations constructed from what already existed before including memories and beliefs, and a powerful subconcious. Most just aren’t prepared for this mental state which can be quite scary if they don’t understand it.
I find it helps to think of time as a concept we use to understand change, rather than a thing, dimension, or some other entity.