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"Closed time-like curves"

Gregory February 20, 2021 at 08:32 8075 views 46 comments
There is a book I saw tonight on Google called Godel meets Einstein. There is another book I've been wanting to get (called The Physicist and the Philosopher) ever since I've seen the author Canalas's you\tube talk on it. Canalas's book is about the Bergson encounter with Einstein wherein the physicist said philosopher's concept of time was dead. I just wanted this to be a quick post on time. It seems to me that our senses and scientific instruments cannot detect time, therefore defining what it exactly is is completely and solely within the realm of philosophy.

So that is my first point. My second one is how I noticed tonight that Godel's ideas of time dovetail with a new idea I have about the big bang. If time can be the reverse of itself, cannot we say that the universe started by "reverse annihilation" ?: that is, just as a pair can, within logic at least, destroy each other, could n't the Big Bang be seen as an annihilation within which time runs backwards? I've actually wondered for awhile now if time really runs backwards. If time can run more than one direction it might solve causality problems related to the question of "origin, and now suddenly I am reminded of ideas from Samuel Alexander.
Thanks

Comments (46)

antor February 28, 2021 at 20:30 #504100
The existence of reverse phenomena may be important sometimes. But you're basically saying creation can be seen as reverse destruction which would kind of lead to reverse time? As a physicist myself, I simply reply "so?". The laws of physics are indifferent to time-reversal so what kind of language we apply to forward or backward in this case is only our purely linguistic decision and it has no impact on the reality of the situation. Look up CPT violation and related topics on wikipedia if youre interested.
Gregory February 28, 2021 at 21:24 #504119
Reply to antor

The PBS digital series on spacetime is now saying, along with other video makers, that gravity is caused by time. If time runs in the opposite direction we think it does, it creates a circular situation wherein time (and thus gravity) is sufficient to understand the start of the universe
Gregory February 28, 2021 at 21:27 #504121
Reply to antor

Are you familiar with the arguments of Aristotle, Aquinas, and Duns Scotus on how motion, causality, and change in the universe cannot to fully explained in physical terms? Answering their arguments is what a theory of everything is really about
Gregory February 28, 2021 at 21:45 #504128
"Closed time-like curves" is Godel's phrase. This question is a physics AND philosophy question. You can't deal with the beginning of the universe in terms of only one or the other. A year ago I thought momentum from gravity was the essential movers, so that the universe was at the state of second "one", and descended from it's state into the motion of inflation. All time (seen as a spatial entity) was from the universe being at it's "top" state and descending, gaining energy from momentum. I've adjusted my position because physicists here in America are saying that time is most fundamental.

Quoting antor
reverse destruction which would kind of lead to reverse time


Reverse destruction was just an expression and the reverse of time is the cause, not something caused by destruction or whatever

Quoting antor
The laws of physics are indifferent to time-reversal so what kind of language we apply to forward or backward in this case is only our purely linguistic decision and it has no impact on the reality of the situation.


Sure, if you want to see it just in terms of math, instead of as it really happened.

javi2541997 March 01, 2021 at 07:01 #504248
Quoting antor
The laws of physics are indifferent to time-reversal so what kind of language we apply to forward or backward in this case is only our purely linguistic decision and it has no impact on the reality of the situation.


Thank you for sharing your thoughts from a professional point of view as physicist. But it is interesting how dependens the notion of "time" in our reality when we introduce it in the vocabulary.
I guess it is impossible to fraction the time, i.e "30 minutes less to end the class" or "how the life flies by" etc...
Probably it isn't impact in terms of reality but it makes a huge impact in our days and living. We fraction the time just to make a chronological order and then make the life "easier" this is another example of how the humankind can be so abstract sometimes. Why the year is ordered by 12 months? Why are we exactly in "2021"? Etc...
Speak about time not only in science but in philosophy is so interesting from my point of view and I guess it is not dead as Einstein or Bergson proposed.
Paul S March 01, 2021 at 12:14 #504332
Quoting Gregory
It seems to me that our senses and scientific instruments cannot detect time, therefore defining what it exactly is is completely and solely within the realm of philosophy.


Energy is spacetime. Spacetime is energy

Our concept of time is an abstraction.
There is no spacetime in the universe as a whole. It exists only where there is sufficient energy.

We are heavy in that we are made of matter, as is our world. Light is invariant. Almost beyond our ability to reason about, it travels at an invariant speed c. i.e. it has no mass (no potential and kinetic energy), no spacetime.
In the beginning there was light. Scientists have now successfully created matter (and antimatter) from high powered lasers.

In doing so they contributed to creating or warping spacetime with photons.
You could argue they created some quanta of time itself, since time is a human abstraction entirely dependent purely on energy.
Gregory March 02, 2021 at 17:47 #504807
Reply to Paul S

In a very real sense we can say time doesnt exist, yes. Descartes and Leibniz said as much. But although time is similar to matter and needs matter, I don't think it is identical to matter. There is something there that is mysterious and which's nature is shown in relativity. Anti-matter has reverse time and i don't think this means just that it acts with the opposite motions of regular matter
Paul S March 02, 2021 at 18:12 #504813
Quoting Gregory
There is something there that is mysterious and which's nature is shown in relativity.


I would argue that the mysteriousness is sourced in a lack of time though.
Light travels at invariant speed because it does not experience time as such.

Relativity only really applies to time as long as there is mass though.
If there is nothing relative to something else, there is no relativity.
If there is no mass around, there are no spacetime effects to perceive.
Banno March 02, 2021 at 18:52 #504821
Quoting Gregory
It seems to me that our senses and scientific instruments cannot detect time, therefore defining what it exactly is is completely and solely within the realm of philosophy.


"It seems to me..." is not an argument.

Curiously, the time of each of your posts is shown directly under them.

Further, I'm writing this after you wrote your post.

So it seems that both we and the sever on which this thread is stored can detect time.

And we can conclude that he evidence is contrary to your assertion.
Gregory March 02, 2021 at 19:30 #504829
Reply to Banno

Nobody denies succession of events. How succession of motions, causes, and change relates to the concept of "time", what time looks like, is a philosophy question. This is especially important since absolute time does not play a role in relativity. Scientists cannot help having philosophical ideas because you can't do science without it. But they don't always realize the many different ways their conclusions can be seen by philosophy. What is a massless particle? Can something come from absolutely nothing? How does Bell's theorem relate to compatabilism? Can a particle be at two places at once or is it really two particles? There are innumerable such questions and they relate to philosophy as much as to science
Banno March 02, 2021 at 19:33 #504832
Reply to Gregory You simply avoided the point: our senses and scientific instruments can detect time.


Gregory March 02, 2021 at 19:35 #504833
Reply to Banno

They detect change, but saying change IS time is a philosophical theory
Gregory March 02, 2021 at 19:36 #504834
The same applies to waves being called "processes". Ontology can ask "processes of what?" Can a process be fundamental? That's philosophy
Banno March 02, 2021 at 19:42 #504835
Quoting Gregory
They detect change, but saying change IS time is a philosophical theory


I didn't say change is time. I said that you are wrong to claim our senses and scientific instruments can detect time.

Gregory March 02, 2021 at 19:45 #504837
Reply to Banno

That depends on your philosophical understanding of time. What some scientists call time we can detect. What some philosophers call time time you can't detect. And positions inbetween these two is an area where philosophers and scientists should communicate on what they mean by time
Banno March 02, 2021 at 19:46 #504838
As for Bergson and Einstein, a good analogy can be made by translating their difference into spacial positions instead of temporal positions.

Bergson was claiming that the only directions were left and right. Einstein, tha the only directions were north and south. Neither was right.
Banno March 02, 2021 at 19:47 #504839
Quoting Gregory
That depends on your philosophical understanding of time.


Indeed; if you wilfully misunderstand the notion of time, you can convince yourself that there is a mystery where there isn't.

Our senses and scientific instruments can detect time.
Gregory March 02, 2021 at 19:49 #504841
Reply to Banno

Measuring something is not detection. That's the confusion here. How to conceptualize these things can not be done fully in terms of measurement
Gregory March 02, 2021 at 20:03 #504844
https://en.wikipedia.org/wiki/Philosophy_of_science

This is a real field of study
Banno March 02, 2021 at 20:15 #504847
Quoting Gregory
Measuring something is not detection.


Hmm. So you are saying that we can measure time but not detect it.

With a straight face?
Gregory March 02, 2021 at 21:14 #504865
Reply to Banno

I don't know why you dislike philosophy in how it applies to science but science can't do without philosophy whether you like it or dislike it
jgill March 03, 2021 at 00:19 #504905
Quoting Gregory
. . . but science can't do without philosophy whether you like it or dislike it


Progress in science requires lots of speculation by scientists, and some of this could be called philosophy. But to stipulate that philosophers untrained in science can trigger scientific revolutions is a stretch. :roll:
Gregory March 03, 2021 at 00:30 #504907
Reply to jgill

Their ideas bring paradigm shifts which allow scientist to frame theoretical matters in new ways. Philosophers don't do the measurements but measurements can never stand alone without conceptualization of them and those concepts have much to do with what is discussed in philosophy.
jgill March 03, 2021 at 00:38 #504911
Quoting Gregory
Their ideas bring paradigm shifts which allow scientist to frame theoretical matters in new ways. Philosophers don't do the measurements but measurements can never stand alone without conceptualization of them and those concepts have much to do with what is discussed in philosophy


You may have a point, but I am unconvinced. You would have to demonstrate this philosophical prowess in examples in the modern world, not olden times.
Gregory March 03, 2021 at 01:17 #504930
Reply to jgill

Take the example of whether you would go back in time of you went faster than the speed of light. Measurements say it can't be done but speculation on it is done by scientist and this might be fruitful for other aspects of science. And since it's not based on measurement it is philosophical science at that point.
Gregory March 03, 2021 at 02:05 #504951
Penrose's conformal cyclic cosmology says, according to his interviews, that the universe will expand until "it no longer knows what size it is". You have to think philosophically to unpack what that means
Banno March 03, 2021 at 02:10 #504953
Quoting Gregory
I don't know why you dislike philosophy in how it applies to science..

I don't.

If what you say is to have any impact at all it ought at the least be factually correct. Our senses and scientific instruments can detect time. Denying this will not win agreement amongst philosophers, nor scientists.

Gregory March 03, 2021 at 02:19 #504959
Reply to Banno

You can't tell what time is through measurement. You can't say if it's matter or not matter. You can't say anything about it from measurement.
Gregory March 03, 2021 at 02:29 #504962
How can physicists attempt to explain the quantum eraser experiment if they aren't to use any philosophy?
Banno March 03, 2021 at 02:36 #504966
Quoting Gregory
You can't tell what time is through measurement.


Time is what clocks measure.

Can't see this going anywhere.

Quoting jgill
You may have a point, but I am unconvinced.

The point being that philosophers can help scientists with conceptual orientation?


Gregory March 03, 2021 at 02:39 #504967
Reply to Banno

You can't go from looking a clock to conceptualizing General Relativity without thinking philosophically. Scientists don't need to think about philosophy all the time but they do this often while doing theoretical physics
jgill March 03, 2021 at 04:01 #504989
Quoting Gregory
Penrose's conformal cyclic cosmology says, according to his interviews, that the universe will expand until "it no longer knows what size it is". You have to think philosophically to unpack what that means


And that is precisely what the Nobel Prize mathematician/physicist, Penrose, tosses at us. His is philosophical speculation by a revered scientist - not a non-scientist philosopher. That was my point. To philosophize in modern science one needs a science background.

Quoting Banno
The point being that philosophers can help scientists with conceptual orientation?


Yes, those poor scientists need a course in critical thinking skills taught by a philosopher. :roll:
jgill March 03, 2021 at 04:03 #504990
Quoting Gregory
Scientists don't need to think about philosophy all the time but they do this often while doing theoretical physics


No argument from me.
Banno March 03, 2021 at 06:09 #505013
Reply to Gregory
Perhaps. But that's not what was contentious in your OP.
Gregory March 03, 2021 at 21:50 #505301
Reply to Banno

I thought it was clear that by "detecting time" i meant finding out what it was and what's it's internal structure was. What I was saying in the OP is that its conceivable for two particles to annihilate each other and go to nothing. If time reversal is involved the annihilation would appear to us like something coming out of seer nothing
Gregory March 03, 2021 at 22:08 #505309
When we try to connect the idea of light being in eternity and it having a constant speed (fastest in the universe) the thoughts aren't very distinguishable from philosophy. I don't think a clear line can be drawn. That was my point on that. On time, when anyone (Neitzsche or whoever) speak of cyclic time, surely they mean something more than imagining time on a circle instead of a line. A line can be turned into a circle by the imagination and vice verse. What cyclic time means is what I wanted to discuss further if anyone is interested and has some thoughts
Banno March 04, 2021 at 05:35 #505479
Quoting Gregory
I thought it was clear that by "detecting time" i meant finding out what it was and what's it's internal structure was


So you use "detecting" to mean "defining".
Gregory March 04, 2021 at 16:17 #505644
Reply to Banno The

I meant a physical detection where we find characteristics of it.
Banno March 04, 2021 at 19:32 #505717
Quoting Gregory
I meant a physical detection where we find characteristics of it.


...like, a clock.
Gregory March 04, 2021 at 19:38 #505719
Reply to Banno

Name the top 5 things you know about the nature of time which reveal what it is since you so want to find a problem where there isn't one
Gregory March 04, 2021 at 19:58 #505727
Reply to Banno

As I said earlier, some physicists now have said time causes gravity instead of gravity causing time. So I asked "what is time then". You keep saying over and over again "time is what clocks measure" but that's not pertinent to anything I was addressing.
Banno March 04, 2021 at 20:03 #505728
Quoting Gregory
Name the top 5 things you know about the nature of time which reveal what it is


I'll show you what time is - later.
Gregory March 04, 2021 at 20:07 #505732
Reply to Banno

Huh. Nothing you've said addresses what time reversal is or what time is
Banno March 04, 2021 at 20:24 #505738
Reply to Gregory This statement, made after my previous one, shows exactly what time is.

That you cannot see this is a fact about you, not about time.
Gregory March 04, 2021 at 21:46 #505784
Reply to Banno

I was more interested in for example Heidegger's last section of Being and Time and other such writings, and how they relate to physics. Science and philosophical thought are very much intertwined and it's interesting how they are connected
Banno March 04, 2021 at 22:50 #505801
Quoting Gregory
I was more interested in for example Heidegger's last section of Being and Time


Yep.