Posted on 12/20/2014 7:58:27 PM PST by LibWhacker
When Albert Einstein’s good friend Michele Besso died in 1955, just a few weeks before Einstein’s own death, Einstein wrote a letter to Besso’s family in which he put forward a scientist’s consolation: “This is not important. For us who are convinced physicists, the distinction between past, present, and future is only an illusion, however persistent.”
The idea that time is an illusion is an old one, predating any Times Square ball drop or champagne celebrations. It reaches back to the days of Heraclitus and Parmenides, pre-Socratic thinkers who are staples of introductory philosophy courses. Heraclitus argued that the primary feature of the universe is that it is always changing. Parmenides, foreshadowing Einstein, countered by suggesting that there was no such thing as change. Put into modern language, Parmenides believed the universe is the set of all moments at once. The entire history of the universe simply is.
Today we would call this the “eternalist” or “block universe” view—thinking of space and time together as a single four-dimensional collection of events, rather than a three-dimensional world that evolves over time. Besides Parmenides and Einstein, this picture is shared by the Tralfamadorians, an alien race who appear in Kurt Vonnegut’s novel Slaughterhouse-Five. To a being from Tralfamadore, visiting the past is no harder than walking down the street.
This “timeless” view of the universe goes against our usual thinking. We perceive our lives as unfolding. But it has adherents even in contemporary physics. The laws of nature, as we currently understand them, treat all moments as equally real. No one is picked out as special; the laws simply say how any moment relates to the previous one and to the next.
Perhaps the most energetic and persistent advocate of the claim that time is illusory is the British physicist Julian Barbour. Impressively, Barbour has managed to do interesting research in physics for decades now without any academic position, publishing dozens of papers in respected journals. He has supported himself in part by translating technical papers from Russian to English—in his spare time, tirelessly investigating the idea that time does not exist, constructing theoretical models of classical and quantum gravity in which time plays no fundamental role.
We have to be a little careful about what we mean by “time does not exist.” Even Parmenides or Barbour would acknowledge the existence of clocks, or of the concept of being late. At issue is whether each subsequent moment is brought into existence from the previous moment by the passage of time. Think of a movie, back in the days when most movies were projected from actual reels of film. You could watch the movie, see what happened and talk sensibly about how long the whole thing lasted. But you could also sneak into the projection room, assemble the reels of the film, and look at them all at once. The anti-time perspective says that the best way to think about the universe is, similarly, as a collection of the frames.
There has, predictably, been some pushback. Tim Maudlin, a philosopher, and Lee Smolin, a physicist, have argued vociferously that time is real, and that the passage of time plays what we might call a generative role: It indeed brings the future into existence. They think of time as an active player rather than a mere bookkeeping device.
Both researchers have been developing new mathematical tools and physical models to buttress their views. Maudlin’s novel approach focuses on the topology of spacetime itself—how different points in the universe are sewn together. Whereas traditional topology uses regions of space as fundamental building blocks, Maudlin takes worldlines (paths of particles through time) as the most basic object. From there, time evolution seems like a central feature of physics.
Smolin, in contrast, has suggested that the laws of physics themselves are evolving with time. We wouldn’t notice this from moment to moment, but over cosmological time scales, the parameters we think of as fixed may eventually take on very different values.
There is, perhaps, a judicious middle position between insisting on the centrality of time and denying its existence. Something can be real—actually existing, not merely illusory—and yet not be fundamental. Scientists used to think that heat, for example, was a fluidlike substance, called “caloric,” that flowed from hot objects to colder ones. These days we know better: Heat is simply the random motions of the atoms and molecules out of which objects are made. Heat is still real, but it’s been explained at a deeper level. It emerges out of a more comprehensive understanding.
Perhaps time is like that. Someday, when the ultimate laws of physics are in our grasp, we may discover that the notion of time isn’t actually essential. Time might instead emerge to play an important role in the macroscopic world of our experience, even if it is nowhere to be found in the final Theory of Everything.
In that case, I would have no trouble saying that time is “real.” I know what it means to grow older or to celebrate an anniversary whether or not time is “fundamental.” And either way, I can still wish people a Happy New Year in good conscience.
“This is not important. For us who are convinced physicists, the distinction between past, present, and future is only an illusion, however persistent.”
I wonder if Einstein ever got out of a parking ticket with argument?
Are you saying time is as real as she is? Because she’s not real!!! :-)
Time is certainly real to me. “And therefore never send to know for whom the bell tolls; It tolls for thee” - John Donne”
So let's assume that we live in one space-time continuum.
You probably could travel back in time, just as we travel spatially. What keeps it from happening though is that it takes a huge amount of energy (because you're changing the fabric of space-time to a much greater degree when you time travel than when you space travel), so it's not going to happen.
Gravity and time both go one way. Go figure.
Albert Einstein’s secretary was so burdened with inquiries as to the meaning of “relativity” that the professor decided to help her out. He told her to answer the inquiries as follows: “When you sit with a nice girl for two hours you think it’s only a minute, but when you sit on a hot stove for a minute you think it’s two hours. That’s relativity.”
Talked to a guy a few days ago that said something like....Time is merely a convenient choice to experience the physical world. There is no there. And if anything is moving or occupying place it is consciousness.
He did have good wine.
Never considered that before, but it's true... Whether you're going very far into the future, or the past according to some theories, the energy expenditure is enormous, thanks! I won't forget; it says something about the nature of the temporal dimension.
And good weed I’ll bet, too! ;-)
He has lots of spare time?
This poor woman seems to do the same thing time and time again
Interesting. At least some physicists seem to be approaching an understanding of the Eternal Now.
Time travel is analogous to ordinary space travel as follows:
To do other than inertial space travel, you apply force to an object’s ordinary matter. (F = ma.)
To do other than inertial time travel, you apply force to an object’s “time-matter.” (Inertial time travel is the usual past-present-future time flow.)
The problem is, “time-matter,” unlike ordinary matter, is an enormous number.
That’s why you only see inertial time travel.
Possibly for a subatomic particle like a photon, the measure of “time-matter” is small enough that we might send one on noninertial time travel.
In previous post, it’d be better to say “mass” and “time-mass” rather than “matter” and “time-matter.”
(The theory is still under construction.)
Now we have to look at "time-mass."
You know about quantum entanglement. There’s also “time entanglement.” This is where our present conditions are a function of past conditions. Our present-time is “time-entangled” with the past.
Now if you go back in time and change the past, AND assuming that there’s no “many-world” situation where you have multiple timelines, you’re going to change the future.
This “time-entanglement” then ripples through space-time and changes everything.
Can you imagine how much energy this would entail? Practically infinite for a human-level past-changing event. Which is why it never happens.
But for a photon, the ripple from time-traveling may be small enough that it would have a minimal effect, or be swamped by background “noise.”
And there’s another analogy — quantum fluctuations and time fluctuations. Maybe they’re the same thing.
Itr could be that the enormous value of “time-mass” compared to ordinary mass, is that “time-entanglement” is much stickier than quantum entanglement.
In fact, time-mass and time-entanglement may be the same thing.
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