
Time might only exist in your head - hellofunk
https://www.wired.com/2016/09/arrow-of-time/amp
======
vog
The argument is deeply flawed.

1) A term doesn't become imaginary just because it turned out to be physically
more elaborate than its initial meaning.

The concept of time never vasnished. It just changed a bit. It is still one of
the axes of spacetime.

2) The logic itself is flawed. Saying "Time might only exist in your head ...
because of spacetime" is like saying:

* "Magnetism might only exist in your head ... because of electromagnetism"

* "Electricity might only exist in your head ... because of electromagnetism"

* "Atoms [meaning: individable parts] might only exist in your head ... because of electrons/protons/neutrons"

3) Even from a purely philosophical view, pointing out time here is
meaningless. Every word describes a concept, a model, so anything including
spacetime might exist just in our heads. Pointing that out specifically for
time makes no sense.

~~~
chc
It seems pretty clear to me from reading the article that the headline is
simply using "time" as a shorthand for "the arrow of time," and the article
tends to refer to the arrow explicitly. This is a common usage (e.g. "if I
could turn back time"), so I don't feel like it's particularly objectionable.

~~~
vog
Even with that interpretation, the article is flawed, which I explained in
another comment:
[https://news.ycombinator.com/item?id=15424006](https://news.ycombinator.com/item?id=15424006)

------
danbruc
That's a bad article not really worth reading. The author either did not
understand what he is talking about or did a quite bad job communicating the
ideas. There are huge gaps in the article and you won't be any wiser after
reading it.

~~~
coldtea
So, like this comment? Which doesn't give any counter-argument at all...

~~~
danbruc
Those are two different things, a badly written article failing to communicate
a theory well on the one hand and and a bad theory on the other hand. I wrote
the comment because of the former so that people coming to the comments first
can decide to not read the article if they believe my comment. And while I
tend to dismiss the idea of time being fundamentally linked to brains because
of what I know and don't know about the inner workings of the universe, I did
not express any opinion about the theory itself because the article left me
pretty clueless what exactly the theory is and I also did not dig any further,
for example read the actual paper.

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keldaris
As a physicist, all this talk about the "meaning of time" (which has been
going on for centuries and in the modern form for decades) seems completely
meaningless. This article, as far as I can discern, makes no scientific claims
or arguments and has no measurable consequences. I guess it might be good
material for drunken conversations if you like passing time that way, but I
don't really see any other use for it.

~~~
pdimitar
Agreed.

During such a drunken conversation I'd simply say "so when a car hits me
because I misjudged the right moment to cross over, the pain is only in my
head and it doesn't exist?" and would laugh.

That's exactly how much value I see in this article. It says absolutely
nothing of substance. It doesn't even have philosophical value.

~~~
coldtea
> _During such a drunken conversation I 'd simply say "so when a car hits me
> because I misjudged the right moment to cross over, the pain is only in my
> head and it doesn't exist?" and would laugh._

Repeating a tired millennia old argument that crudely stops any inquiring talk
for anything that's not directly measurable (and/or doesn't translate into
money or some direct benefit)...

But while the grandparent started with "As a physicist", as if this conveys
the consensus among physicists, they forgot to mention that many physicists
(including celebrated physicists) are indeed very interested in the meaning
and the philosophy behind physics concepts, and there have been excellent
forays into such matter, without going into BS Chopra territory.

~~~
keldaris
> while the grandparent started with "As a physicist", as if this conveys the
> consensus among physicists, they forgot to mention that many physicists
> (including celebrated physicists) are indeed very interested in the meaning
> and the philosophy behind physics concepts

I wasn't trying to convey any "consensus" among physicists, merely make
abundantly clear that the specific article in question does not appear to
contain any discernible novel scientific or philosophical content. You're
perfectly right in saying that plenty of great physicists are indeed
interested in the philosophy of science (though many more are not), and that's
fine. This article and the ideas it represents aren't a part of that.

------
augustt
Not AMP link: [https://www.wired.com/2016/09/arrow-of-
time](https://www.wired.com/2016/09/arrow-of-time)

------
lisper
Here's another take on the topic:

[http://blog.rongarret.info/2014/10/parallel-universes-and-
ar...](http://blog.rongarret.info/2014/10/parallel-universes-and-arrow-of-
time.html)

The TL;DR:

"The punch line is this: the statement that we can't time-travel into the past
is exactly the same as the statement that we can only remember the past. It is
not the case that one causes the other, it is that the two things are
logically equivalent. Your perception of "traveling through time" emerges from
your mental states and not the other way around. You feel like you are
"traveling forward through time" because your mental states have this natural
order to them. You can remember the past and not the future because whatever
you remember _is_ your past. The laws of quantum mechanics (and entanglement
in particular) insure that what any given instance of you remembers appears to
be a continuous and coherent sequence that behaves according to regularities
that we call the laws of physics. But in fact you do not travel through time,
because at root there is no you, and there is no time. There is only the
wavefunction, from which both you and time emerge as an approximation."

~~~
dingbat
so how does quantum mechanics explain the continuous and coherent (more or
less) sequence that is perceived even in a non-physical dream?

~~~
lisper
In exactly the same way. Dreams are just the brain "remembering" internally
generated stimuli.

~~~
dingbat
if it's exactly the same, that would imply that quantum mechanics and
decoherence effects are equivalent for both internally generated imaginary
stimuli, and external stimuli based on "real" physical objects. but it seems
like a stretch to suggest that if i dream that i am flying, that the same
quantum mechanical effects that contribute to Time's Arrow in that dream are
in play in the "real world", where such a thing would be impossible
physically.

~~~
lisper
I think you're missing something really fundamental. Decoherence happens at
the sub-microscopic level -- unless things are very, very cold, in which case
you can get macroscopic quantum effects. But at room temperature, by the time
you get up to the molecular level things are already more-or-less classical.
By the time you get to the level of a neuron they are (as far as we know)
indistinguishable from classical. From the point of view of QM, there is no
difference between being asleep and being awake. All of your mental processes
are indistinguishable from classical.

~~~
dingbat
yes i understand decoherence at different scales, but my point is that the
Arrow of Time exists for both a real physical object, such as someone falling
off a cliff, but also a non-real object, such as someone dreaming of falling
off a cliff. decoherence can explain the first, but since there is no physical
cliff or object in a dream (at either the micro- or macro- scale), how can it
explain Arrow of Time that is observed in interactions between non-physical
imaginary objects?

~~~
lisper
But your _perceptions_ of real and non-real objects (and hence your perception
of time) comes from the same source: the pattern of neurons firing in your
brain. It ultimately doesn't matter whether those neuron firings are caused by
external stimuli from real objects or internal stimuli from imaginary ones.
The nest result is the same: your perception of the passage of time runs in
one direction because your mental states form a totally ordered sequence of
accreting memories. Decoherence insures that those memories remain self-
consistent with each other and with the "real world".

------
joejerryronnie
Random mental musings of a non-physicist after a bit too much coffee:

I wonder if we're just playing at semantics and what "time" means to me is not
what "time" means to quantum physicists. Clearly events unfold in a linear
fashion and we cannot rewind time like a movie and go back to exact events
that have occurred in the past. But "time" defined as a fundamental force of
the universe may be something entirely different, perhaps intertwined with
quantum probability.

Maybe this is how we'll eventually solve faster than light speed intergalactic
travel. Instead of manipulating space, we'll manipulate time - i.e. travel to
a point in time where we probabilistically exist at that location in space. Of
course, once we get there, our perception of time moving in a linear fashion
will "speed things up" to the current time as perceived by all of us.

~~~
leggomylibro
>Clearly events unfold in a linear fashion and we cannot rewind time like a
movie and go back to exact events that have occurred in the past.

I know it's kind of facetious, but we can't flap our arms to fly either, and
that doesn't mean that gravity unfolds in a linear fashion and we cannot
rewind its direction.

Things get a lot simpler if you don't believe in free will. Maybe you could
observe the past or future through some experiment that we haven't figured
out. But you also wouldn't be able to change it. It just is, like space.

A lot of time travel fiction takes that sort of view; plot twist, all of the
protagonists' efforts to change the future they saw actually wind up leading
them straight to it. Gasp!

------
retrogradeorbit
For those interested in the physics of time and the idea of whether time
exists or not, you may find Julian Barbour's work more introductory,
accessible and less esoteric. For example:
[https://www.youtube.com/watch?v=KkjXuS_Z1ds](https://www.youtube.com/watch?v=KkjXuS_Z1ds)

The Wheeler-DeWitt equation is covered at about 40 minutes in, here.

------
_0ffh
If time didn't "exist", then there could not be any advantage in taking time
into consideration in anything. But there clearly is. At the most one could
argue that our definition of time is not perfectly aligned with some
observations me make, which is a different claim entirely.

------
idlewords
In an important sense, everything only exists in my head.

------
TheAdamAndChe
It's always been a puzzle to me about what makes time different from other
dimensions. In the article, it mentions that Lanza has "a theory that space
and time are constructs of biological sensory limitations." This implies that
by shifting the dimension that the biological systems run along, you can
either change the dimension considered "time," or even reverse the direction.
I'm not sure this is possible, though, because of entropy. Movement along any
directional dimension doesn't determine the position or reversibility of
chemical or physical processes, but movement along time does.

------
grondilu
> It's like a macro-scale version of Schrödinger's cat. A faraway corner of
> the universe might be moving future to past. But the moment humans point a
> telescope in that direction, time conforms to the past-future flow.

Mind blown.

------
saimiam
Layperson question coming up -

Say a decohered particle reaches an un-decohered state outside the realms of
our detection. Does this mean that for that particle time didn't elapse? As
far as the particle is concerned, someone observed it and then someone was
unable to observe it.

This hinges on whether a decohered particle can go back to being undecohered.

If the answer is that particles can stop decohering, then our status as
observers is merely a contrivance for us to checkpoint a before decoherence
state and a decoherence state.

------
mrfusion
Or does your head only exist in time?

~~~
rytill
This is more likely.

------
mcguire
" _Here 's where it gets a bit weirder. Although the equation doesn't include
a variable for time (which isn't all that weird. Time is something that can't
be measured in terms of itself, in physics it is measured as correlations
between an object's location ... over time ... anyway, it's weird). But, it
provides a framework for knitting the universe together._"

"Although the equation doesn't include a variable for time [...]."

Really, Wired?

------
ianai
I think time is a fundamental part of spacetime, but it’s constrained by the
second law of thermodynamics. Order always decays and therefore changes in one
direction.

~~~
uoaei
The effects are a little subtler than "everything decays" however I'm with you
that entropy should play a large part in determining our answer to this
question since it is seemingly the only law in our universe which prevents the
reversibility of any reasonably macroscopic phenomenon (putting an egg shell
back together, etc.). It is this distinction from which I believe people learn
to differentiate forward v. backward in time. This is only a hypothesis and I
invite other perspectives to introduce themselves.

------
SubiculumCode
The concept of "observer" always bother me. It seems that a light meter, or a
thermometer, are equally observers as a brain/body is an observer. WHich then
boils down to something like "to interact." Time goes one way because
particles/fields interact. Is this right?

------
dingbat
whether its about decoherence or "observer time", I wonder how either
explanation can explain why Times Arrow seems to exist in dream. ie. if
decoherence was the basis, what is being "decohered" in a dream?

------
tiuPapa
Wait, I always thought time existing only in human conception was the accepted
scientific explanation for time.

~~~
Santosh83
It can't be a _scientific_ explanation, as far as I can see. That needs
experimental testability of concrete predictions. It can be a reasonable
philosophical speculation however.

------
Al-Khwarizmi
This is what Kant said. That space and time are pure forms of sensible
intuition.

