
Is time an illusion? - kqr2
http://www.newscientist.com/article/mg19726391.500-is-time-an-illusion.html?full=true
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jd
Great article - bad title. Saying that time might be an illusion is saying
that time might not be "real". But a different model of time doesn't affect
its realness.

Is temperature an illusion? Certainly not. And yet, as the article says, it's
merely a model of the interaction between molecules.

Some models explain more than other models. Models that explain more are
better. Thinking in terms of real/illusion is not helpful at all.

~~~
chandler
>> Saying that time might be an illusion is saying that time might not be
"real".

No, the word "illusion" references an artifact that is both real and
effective, yet whose true nature is misunderstood.

Moreover, for X to be an illusion, it necessarily _must_ exist in some way.

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cchooper
You're both (a little) wrong! :)

You can't call something an illusion _just_ because its true nature is
misunderstood. An illusion is something that _looks deceptively like something
else_. A hologram of a table is an illusion, but just misunderstanding the
nature of a table (e.g. misunderstanding the fundamental particles from which
it's constructed) does not make it an illusion.

Saying that time is an illusion is like saying that we _appear_ to be living
in a universe with time, but actually we don't. We are in fact experiencing
something that _looks_ like time, but isn't really time.

But obviously we _do_ live in a universe with time, and the fact that time may
turn out to be something strange or unexpected does not make it an illusion.
It just means we misunderstood its true nature.

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TrevorJ
I believe they are saying time is a concept that is useful for explaining
certain local experiences, but under certain more global circumstances, the
defining characteristics of the concept of time could potentially change,
causing us to need a new concept to describe it.

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lionhearted
I've always been more personally inclined to the social sciences - how people
work and interact with each other. It always seemed to me that there's less
red tape and formal background necessary to do interesting and practical work
in social sciences.

But the more I think about it, the more I realize that damn near everything we
do of value relies on hard science. If you had me pick one post-agriculture
profession to be my only formal profession in the world, it'd have to be
engineering. Engineering creates tools that greatly expand the ability of
everyone else to do what they're doing. And yet, without physics and
chemistry, we're not engineering damn near anything of value. Behavioral and
social sciences have made such huge leaps due to increased communication,
mobility, and processing and storing of information. All that can be credited
to some damn amazing engineers, who all needed math and hard science to build
what they did. It makes me remember from time to time, that though I'm not a
hard scientist and will likely never more than dabble in it, it's pretty damn
amazing stuff, and ought to be regularly given a nod of appreciation to its
amazingness.

~~~
mixmax
_"All science is either physics or stamp collecting."_

Ernest Rutherford

~~~
mojuba
All Computer Science is either assembly programming or garbage collecting.

~~~
forinti
All generalizations are bad.

~~~
mojuba
All assumptions about generalizations are generalizations.

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yummyfajitas
Just to clarify: the problem here is wave collapse. Wave collapse happens at
an instant of time, and therefore picks a frame of reference. The wavefunction
changes instantaneously over all space when "measurement" occurs, and does not
obey the Schrodinger equation (or relativistic equivalent).

The "intriguing development" by Rovelli is that he used decoherence to explain
measurement probabilities in some relativistic model. Time still exists in
this model (which lives over R^{3+1}), but nothing happens instantaneously.
Basically, he showed that the relativistic schrodinger equation gives the same
experimental predictions as wave collapse.

~~~
lisper
Wave collapse hasn't been taken seriously by physicists in years. It's been
thoroughly debunked again and again (c.f.
<http://www.npl.washington.edu/npl/int_rep/tiqm/TI_toc.html>,
<http://www.flownet.com/ron/QM.pdf>). The press keeps reporting it because
it's such a delicious mystery.

~~~
yummyfajitas
Which physicists? As far as I know, copehnagen is the mainstream ontology.

I gave a talk last week on decoherence, just working out an explicit example
where we can almost exactly solve the combined particle/measurement device
system. The idea that wave collapse is unnecessary was not uncontroversial.

A quote from before I even gave the talk: "I don't believe you."

~~~
lisper
> Which physicists?

Well, Cramer (the one I cited) for one. David Mermin. Cerf and Adami. Roland
Omnes. John Preskill. How many do you want?

> I gave a talk last week on decoherence

To what audience?

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yummyfajitas
The audience of my talk was mixed math, physics and chemistry with a shared
interest in quantum control.

As for the physicists you cite, the ones I recognize seem to work on either
quantum information or foundations of QM. Decoherence is far more accepted in
these fields than in the rest of physics.

~~~
lisper
Yeah, well, those are the people I would consider the authorities, wouldn't
you?

BTW, collapse is easily debunked: take a two-slit experiment a put a detector
at one slit. Interference is destroyed for all photons despite the "fact" that
only half the photons "actually" interact with the detector. Collapse cannot
account for this. (I put "fact" and "actually" in scare quotes because in true
fact all the photons interact with the detector, but not according to the
collapse theory.)

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euroclydon
Try to define time. Or just go to the wikipedia article and listen to them try
to define it, and digress into a discussion on how some people don't believe
in it.

It's very hard to describe time without using the word time: A series of
events -- What's an event? The best one I have is: Why can't two object occupy
the same space? Well, they can, but at different _times_. Not really an
explanation, but I think it's a good illustration.

Isn't time sort of like goodness, so fundamental that it's indescribable with
invoking itself?

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rationalbeaver
I've always thought of time as a measurement of change. No change, no time
(i.e. if all particles in the universe were frozen in place at absolute zero
then there would be no measurable change and time would not exist).

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lehmannro
What you describe sounds like all particles in the universe suddenly lost all
their energy. If time is change, time must be energy.

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markessien
If time is an illusion, it's a very persistent one.

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Hexstream
It's like physicists are discovering functional programming....

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raamdev
If science eventually proves without-a-doubt that the Big Bang was only one of
many Big Bangs and that in fact, there seems to be no beginning or end to the
Big Bangs, then the universe would essentially be infinite.

If it's determined that the universe, and everything in it, lasts (in one form
or another) forever, then the meaning of time disappears. You cannot have time
unless you have a beginning and an end.

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bianco
Time only needs a beginning, it doesn't need and end.

Nobody can prove the Big Bang theory without-a-doubt: we only could rise
theories against it, or bring facts against it, but it will stay an unproven
theory forever, very similar to math theories: you can't prove them without-a-
doubt, you only can give it credit _currently_ , and because there hasn't been
found any counter example yet.

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baddox
Time is a very real perception, so the answer is "Yes" unless you're asking
the metaphysical question "Is all perception an illusion?"

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anemach
Maybe time only exists if it can be observed.

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paraschopra
Maybe we are wasting our time discussing this. I agree that discussing this
makes us feel intellectually satisfied, but nothing really worthwhile comes
from this discussion.

I think 'Is time an illusion' is akin to asking 'define love'. I know it is
corny.

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skalpelis
Lunchtime - doubly so.

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wallflower
If time is an illusion that might explain why I feel like it disappears.

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bianco
There is a theory that we only do exist because there is an entity outside of
time which 'thinks' us continuously.

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koningrobot
How can an entity that is outside of time think us "continously"?

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bianco
And how would you try to express something which is outside of our own
possible experience? Sure, you could say "eternal present" or something;
doesn't seem to sound much better...

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koningrobot
I wasn't picking on your choice of words. If there is an ever-present
something which effects our universe, and there is change in our universe,
then there must be change in that ever-present something's universe, right? I
mean, I suppose you could look at our universe as just a const 4-dimensional
chunk of data with us simply moving along the time axis, but us moving along
it is still change.

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weegee
time isn't an illusion here where we are now, but it doesn't exist outside of
this physical life-space.

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chiffonade
> Is time an illusion?

Yeah, probably, just like all human sensory input.

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abdulhaq
I have a brilliant proof of this, but I'm so busy it'll have to wait until
tomorrow.

