4 ms·

Time cannot change by definition. Nothing can move in spacetime for the same reason. This is why the late Sir Karl Popper (of falsifiability fame) once compared

by Mapou 18y ago

Time cannot change by definition. Nothing can move in spacetime for the same reason. This is why the late Sir Karl Popper (of falsifiability fame) once compared spacetime to Parmenides' block universe and called it "Eintein's block universe in which nothing ever happens". (Source: Conjectures and Refutations). In his textbook, "Relativity From A to B", renown relativity expert Robert Geroch wrote, "There is no dynamics within space-time itself: nothing ever moves therein; nothing happens; nothing changes." Very few physicists know this but it's the truth, a nasty little truth for some, but the truth nonetheless. In conclusion, any talk of time travel in any direction (forward or backward) is pure crackpottery. There is only the NOW, the ever changing present. Don't mod me down because you have a different opinion. Incessant propaganda and sci-fi movies like Star-Trek have duped a lot of people. Just think about it and figure it out on your own. Nothing can move in spacetime.

ajross 18y ago
You're not explaining that very well. Yes, classic relativity is a deterministic theory which doesn't have a time arrow. You can look at it as a single, static universe defined as the sum of all moments. But that's neither here nor there. Classic relativity is, strictly speaking, wrong: the real universe is, as far as we understand, provably non-deterministic. And in any case, it has nothing to do with this article, which is about the time arrow defined by entropy.
- Mapou 18y ago
  I am not sure exactly what you explained. First off, relativity, like Newtonian mechanics, is a classical physics theory. I am not aware of any such thing as non-classical relativity. So why even say classical relativity? At the very least, it is redundant. Second, of course the universe is probabilistic, a fact that falsifies both relativity and Newtonian physics. Third, the universe is probabilistic precisely because time cannot change. Why? Because, since time is not a variable and is thus non-existent, the universe cannot calculate precise temporal durations. Thus, in order to properly conserve energy, it is forced to use the next best thing: probability. Fourth, this has everything to do with article since entropy, as explained in the text books, assumes the passage of time and thus a time direction or arrow. Since time is abstract, it follows that an arrow of time is imaginary. As a result, it makes perfect sense that one cannot reverse entropy. Or anything else, for that matter. The purpose of my comment was to get people to think and to stop accepting everything they hear on face value. If time cannot change, which is trivially shown to be true (changing time is an oxymoron because it is circular), then all the so-called time-travel conjectures by famous physicists like Kip Thorne, Stephen Hawking, David Deutsch, and many others, are pure crackpottery.
xlnt 18y ago
"nothing ever moves" does not mean that no blocks in the block universe are related in such a way that we can reasonably say the same object is in both. and if the same object is in two or more blocks of the universe, which are different times, then it exists at different times, or in other words travels through time. this doesn't prove traveling back in time, or skipping forward in time is possible, but the concept does make sense in a block universe, and the standard time travel via time passing still works fine. But +1 for quoting Popper.
cousin_it 18y ago
Yes, there's no "time outside time", but maybe there are loops (closed timelike paths) inside the block universe.
- Mapou 18y ago
  I don't think you get it. A block universe in which nothing happens cannot possibly exist since it is clearly falsified. We observe change, do we not? So speaking of loops within a block universe is like arguing about how many angels can dance on the head of a pin. Is it me, or do other people go out of their way to be illogical?
  - cousin_it 18y ago
    Change can be viewed as a sequence of distinct immutable observer-moments, like frames in a movie, and nothing forbids them to form a loop.
    - Mapou 18y ago
      Dude, what is wrong with you? The point that you are missing is that, if you include time as one of the dimensions of the universe, then change becomes impossible. That is the meaning of the block universe. This is why Popper called spacetime, Einstein's block universe in which nothing happens. Counterintuitively, a time dimension does not enable change or motion, it forbids them. The conclusion to be drawn is simple: There are no such things as spacetime or a time dimension and any talk of time travel via closed time-like loops in spacetime is just plain stupid. Guess what that makes those who insist on talking about time-like loops? Stupid, that's what.
      - Mapou 18y ago
        I am fast realizing that YCombinator is turning out to be a den of asteroid orifices where you get modded down by asteroid orifices for telling inconvenient truths. You people are chicken shit and your attempt at censorship is chicken shit. You can't stop people from expressing themselves on the net. YCombinator is not the only outlet for expression, you know. I express myself freely on my blog and I get hundreds and often thousands of hits a day. You asteroid orifices can't stop that. IOW, F*ck you and the mule you sleep with. LOL.

by Mapou 18y ago

ajross 18y ago

You're not explaining that very well. Yes, classic relativity is a deterministic theory which doesn't have a time arrow. You can look at it as a single, static universe defined as the sum of all moments. But that's neither here nor there. Classic relativity is, strictly speaking, wrong: the real universe is, as far as we understand, provably non-deterministic. And in any case, it has nothing to do with this article, which is about the time arrow defined by entropy.

Mapou 18y ago
I am not sure exactly what you explained. First off, relativity, like Newtonian mechanics, is a classical physics theory. I am not aware of any such thing as non-classical relativity. So why even say classical relativity? At the very least, it is redundant. Second, of course the universe is probabilistic, a fact that falsifies both relativity and Newtonian physics. Third, the universe is probabilistic precisely because time cannot change. Why? Because, since time is not a variable and is thus non-existent, the universe cannot calculate precise temporal durations. Thus, in order to properly conserve energy, it is forced to use the next best thing: probability. Fourth, this has everything to do with article since entropy, as explained in the text books, assumes the passage of time and thus a time direction or arrow. Since time is abstract, it follows that an arrow of time is imaginary. As a result, it makes perfect sense that one cannot reverse entropy. Or anything else, for that matter. The purpose of my comment was to get people to think and to stop accepting everything they hear on face value. If time cannot change, which is trivially shown to be true (changing time is an oxymoron because it is circular), then all the so-called time-travel conjectures by famous physicists like Kip Thorne, Stephen Hawking, David Deutsch, and many others, are pure crackpottery.

xlnt 18y ago

"nothing ever moves" does not mean that no blocks in the block universe are related in such a way that we can reasonably say the same object is in both. and if the same object is in two or more blocks of the universe, which are different times, then it exists at different times, or in other words travels through time. this doesn't prove traveling back in time, or skipping forward in time is possible, but the concept does make sense in a block universe, and the standard time travel via time passing still works fine. But +1 for quoting Popper.

cousin_it 18y ago

Yes, there's no "time outside time", but maybe there are loops (closed timelike paths) inside the block universe.

Mapou 18y ago
I don't think you get it. A block universe in which nothing happens cannot possibly exist since it is clearly falsified. We observe change, do we not? So speaking of loops within a block universe is like arguing about how many angels can dance on the head of a pin. Is it me, or do other people go out of their way to be illogical?
- cousin_it 18y ago
  Change can be viewed as a sequence of distinct immutable observer-moments, like frames in a movie, and nothing forbids them to form a loop.
  - Mapou 18y ago
    Dude, what is wrong with you? The point that you are missing is that, if you include time as one of the dimensions of the universe, then change becomes impossible. That is the meaning of the block universe. This is why Popper called spacetime, Einstein's block universe in which nothing happens. Counterintuitively, a time dimension does not enable change or motion, it forbids them. The conclusion to be drawn is simple: There are no such things as spacetime or a time dimension and any talk of time travel via closed time-like loops in spacetime is just plain stupid. Guess what that makes those who insist on talking about time-like loops? Stupid, that's what.
    - Mapou 18y ago
      I am fast realizing that YCombinator is turning out to be a den of asteroid orifices where you get modded down by asteroid orifices for telling inconvenient truths. You people are chicken shit and your attempt at censorship is chicken shit. You can't stop people from expressing themselves on the net. YCombinator is not the only outlet for expression, you know. I express myself freely on my blog and I get hundreds and often thousands of hits a day. You asteroid orifices can't stop that. IOW, F*ck you and the mule you sleep with. LOL.