
Problem of Time - sytelus
https://en.wikipedia.org/wiki/Problem_of_time
======
Der_Einzige
Is there any evidence of a fundemental quantized unit of time existing? Can I
fundementally treat time as continuous or discrete? Plank time isn't good
enough because it's possible that we see a phenomenon that happens over a
shorter time period and that we need better instruments.

This question very important to me because I don't see a possibility that we
can situate identity as existing metaphysically without quantized time. It
also seems to imply to me that determinism is wrong.

But please correct me on this you big-brains I don't study quantum physics or
general relativity

~~~
wnoise
There is not. Both quantum physics and special and general relativity treat
time as continuous.

------
mellosouls
So far many of the comments seem to have misread the article, which doesn't
seek to address the mystery of what time is directly, but rather it describes
a supposed mismatch between quantum and classical (via general relativity)
interpretations of it's essence.

~~~
skat20phys
I don't mean to sound snarky, but aren't those two problems related?

~~~
mellosouls
Sure, and the article goes on to discuss time itself as a necessary
consideration, but it's not the main focus - the title is somewhat misleading.

------
KingFelix
The Order of Time - Carlo Rovalli, great read if anyone is looking for a book
on time.

Also, Your brain is a time machine - Dean Buonomano

~~~
niketdesai
Thanks for the recommendation. I'm going to check out Rovalli's book.

------
peter_d_sherman
Excerpt:

The quantum concept of time was invented by physicist Bryce DeWitt in the
1960s:[5]

 _" Different times are special cases of different universes."_

------
badrabbit
Let me ask you this: if there was no change, no interaction even between
qanta, would there be time?

~~~
colinhb
Think of a donut. Think of a vertical plane through the donut. The plane has
two disconnected circles on it. Imagine trying to move the two circles apart.
They resist your effort because they are attached together through their
three-dimensional structure.

In one view of time (“eternalism”, roughly speaking) saying “there is no
change” or “no interaction” between any particles in the universe would mean
that in the fixed structure of the universe of which time is a dimension,
everything is constant in the direction of that dimension.

So the two statements become roughly equivalent.

------
enricozb
> no known physical laws seem to require a single direction.

What would a physical law that required a single direction look like?

~~~
hoorayimhelping
I believe it looks like this:
[https://en.wikipedia.org/wiki/Speed_of_light](https://en.wikipedia.org/wiki/Speed_of_light)

That physical limitation on how fast a mass can move is what keeps causality
in check and things like the grandfather paradox from being possible.

Edit: now that I think more on it, this is probably a better law that ensures
causality:
[https://en.wikipedia.org/wiki/Entropy#Second_law_of_thermody...](https://en.wikipedia.org/wiki/Entropy#Second_law_of_thermodynamics)

------
ethn
As another HN member mentioned, this is a pretty awful article. What is the
alleged conflict supposed to be?

It's my understanding that quantum mechanics necessarily describes systems in
a single inertial reference frame, so for that system, time is absolute w.r.t
to both general relativity and QM.

~~~
lonelappde
As the article explains, time in Relativity is not Absolute, it's....
Relative.

~~~
ethn
In General Relativity time is absolute throughout the same inertial reference
frame...

------
Vysero
Why do I get the feeling that when they do finally figure out what time is
it's somehow going to be related to imaginary numbers:

The complexity of things - the things within things - just seems to be
endless. I mean nothing is easy, nothing is simple. ~Alice Munro

------
greenstork
Isn't time just a history of movement? For example, if you stopped the
movement of everything in the universe (all the way down to subatomic
particles) for a "moment" and then turned movement back on again, how long
would that moment have lasted for? 1 second or 100 years? There's no way to
define how long that moment lasted, since nothing was moving during that
moment. So it seems to me that time cannot exist without movement which makes
me think that time is a byproduct of motion (a history of motion).

~~~
Yajirobe
> how long would that moment have lasted for?

0 seconds.

------
Razengan
Maybe I’m not smart enough to find time as confusing as these things try to
point out:

Time is the sequence of states every time the rules are applied, or am I
missing something?

~~~
mjfl
According to general relativity, the time order of events is relative
depending on your position and velocity. This also seems to break causality in
textbook quantum mechanics since local changes can lead to global adjustments
(collapse, for one) of the wavefunction.

------
saagarjha
This is a pretty awful Wikipedia article. Unless it’s a plea for an actual
expert in the field to go in and fix it, I’m not seeing how this is a good
submission :(

~~~
stagas
It is an interesting discussion topic, people are confined to their houses for
many days now and naturally experience existential issues. And, because noone
sees the world the same way, HN relies on a sophisticated algorithm that tries
to minimize bias on what is a good and what is a bad submission. A more
constructive approach would be to point out why you think it is an awful
article and share some knowledge on the topic.

~~~
mjfisher
Just to add to what saagarjha said; there's large parts of the article that
just don't seem to make sense on their own. I only have a Master's degree in
Physics, and haven't specialized in general relativity - nevertheless I
usually have enough background to at least follow along with Wikipedia.

In particular, the "Overturning of absolute time in general relativity"
section is very hard to follow, and I suspect would only make passing sense to
a reader already very familiar with the subject matter. It has a very stream-
of-consciousness feel to it, it doesn't introduce concepts as it moves along,
and it makes unexplained logical leaps from one idea to another.

I'm glad someone took the time to start the article and it sounds like an
interesting subject; but it could certainly see improvement from someone with
the right knowledge.

~~~
acqq
I think that the article which supports its definition of the problem with the
article written by an author who "obtained a bachelor's degree in physics" and
then "left graduate school during the first year in order to pursue a career
in science journalism, and "has never looked back"" (1) should just not exist.

In my perception, even that article is such a "popularization" of the topics
on which physicists work that it stopped "being even true." The Wikipedia
article just continues in that direction.

The "problem" that exists should not even be present as a Wikipedia entry
under that specific name. As far as I see it, even the name is wrong.

\---

1)
[https://en.wikipedia.org/wiki/Natalie_Wolchover](https://en.wikipedia.org/wiki/Natalie_Wolchover)

~~~
chupa-chups
TBH, >95% of the commentators here don't reach the education level of the
editor of the article _by far_ in terms of the specific domain, but still this
doesn't stop them from criticizing it.

Not meant to be snarky, and in general imho it is good the be critical always
- but this should include oneself. The latter part is often lacking, and the
amount of lacking very often appears to be proportional to the lack of
knowledge of the commentator.

~~~
acqq
> The latter part is often lacking, and the amount of lacking very often
> appears to be proportional to the lack of knowledge of the commentator.

Very good: how does your comment fare using that frame?

And since you commented under my comment, what parts of my comment do you
agree with and what do you thing you can correct, and based on which sources?
I've given mine.

~~~
chupa-chups
Maybe i misunderstood your comment, if so I like to apologize.

In any case, would you please explain to me how you consider the title "The
problem of time" being wrong. It appears to me as one of the most fundamental
questions in physics. The wikipedia article does - from my PoV - a reasonably
good try to explain the problem at hand in laymans terms. It touches the
relevant aspects of the problem (no absolute time, time/space interdependency)
and expands to a more speculative theory (thermal time hypothesis).

I will not at all claim to have even a basic understanding of the covered
topics, despite being an avid reader of related bloggers and papers.

I just am astonished how people disregard work of others even without (basic)
knowledge of the domain. Maybe I'm wrong, but noone in this thread even tried
to show her/his accomplishments in the mentioned domain.

And thanks for replying without simply downvoting.

And please don't think i automatically included _you_ in the perceived group
not having "even a basic understanding o the topic". Maybe you have, but since
this is even less recognizable than the merits of the wikipedia author it is -
from an outside PoV - even less credible.

~~~
acqq
> how you consider the title "The problem of time" being wrong.

Because as far as I understand it is not commonly accepted name among the
physicists for the issues that prevents them developing the "Theory of
Everything"

[https://en.wikipedia.org/wiki/Theory_of_everything](https://en.wikipedia.org/wiki/Theory_of_everything)

It's just how only a few authors name their articles and books. The title
would be OK if it would be a title of the article about the specific book, but
not as a title for the "problem" of physics. Because, as far as I know, it's
not commonly called as such among the physicists, and that's why even the very
support for the whole wikipedia article is a reference to the Quanta article
and not some physics textbook, and that is what then confuses readers who
don't have "even a basic understanding of the covered topics."

Reducing all the issues about "TOE" to the "problem of time" is not correct,
from the perspective of physics. It is probably "fun" for "philosophers"
though.

------
DrFell
The problem of time comes from the notion that we are matter existing through
time, instead of realizing sentience is made of events.

~~~
teilo
Precise clocks don't care about your sentience or lack thereof. They still
measure the gravity and speed-induced time dilation that is entirely missing
in quantum mechanics. Relativity is a physical phenomenon that does not
require sentience to operate, and time is part of that physical phenomenon.

~~~
blfr
_Relativity is a physical phenomenon that does not require sentience to
operate_

We do not and cannot know that because all observations me make involve
sentience. In fact, we can't even know if anything exists without sentience.

~~~
JoeAltmaier
Nope. The universe 'notices', by reacting in exactly the way you'd expect if
relativity was happening.

That last bit - "...we can't even know.." is sophistry.

~~~
blfr
There is nothing sophistic about this argument. It's pretty obvious.

This is why some people argue that we might be living in a simulation. Because
we don't have direct (not mediated by our senses) access to the underlying
reality.

~~~
JoeAltmaier
True about everything, including relativity. Can't have the argument without
assuming it.

The fact is, the universe operates consistent with Relativity.

