
At Multiverse Impasse, a New Theory of Scale - akrymski
http://www.simonsfoundation.org/quanta/20140818-at-multiverse-impasse-a-new-theory-of-scale/
======
givan
I wonder if it's possible to ever find out what our reality is even if we will
eventually reach the intellectual and technology necessary because we are part
of it and it's probably impossible to have an objective view of the matter.

~~~
axilmar
I do not think that it is possible.

Any physical system that can be described by a set of mathematical laws is
bound to have some axioms that simply cannot be proven within its context.
Godel's incompleteness theorems prove that.

Hence, we will never get to the bottom of the reality of our universe.

~~~
smokel
Your statement that we will never get to the bottom may be true, but the
reasoning is flawed.

Gödel's incompleteness theorems are about mathematical theories, not about
physical theories. It may well be that for physical understanding a very
limited arithmetic is sufficient. Also, there may be statements that are
unprovable, but these might turn out to be irrelevant to sufficiently
understanding the universe.

Also, an axiom, by definition, can not be proven. The things that are proven
are theorems, statements, etc. An axiom is an assumption.

Eventually, it all depends on what level of understanding you want. But
Gödel's theorems have little to do with that.

~~~
mkaziz
Do you not have to start off with a set of axioms though? Assumptions that
will never be proven?

~~~
dfox
From the mathematical point of view, physics is about finding smallest set of
axioms from which you can mathematically derive complete theory of universe's
behavior. Validity of such axioms is in turn validated by experiments (by
testing whether results match theory derived from given axioms)

~~~
dllthomas
It _is_ true that they will never be "proven", but that doesn't mean we can't
build a tremendous confidence in them through experimentation. (Which is to
say "I agree", but I wanted to put a slightly different spin on it.)

------
MisterMashable
There's a very subtle undertone of negativity in this article about physics.
Before I get into, William Bardeen is not in the same league as 'Surfer Dude
and his E8 Theory of Everything' which throws basic facts about representation
theory out the window, coming up with 'todalay boogus' arguments which amazes
auntie, mommie and magazine editors but a real physicist would instantly
dismiss.

Bardeen is the real deal. His papers are very interesting and feel a bit like
reading Sidney Coleman's papers. If you're interested...

[http://arxiv.org/find/hep-
th/1/au:+Bardeen_W/0/1/0/all/0/1](http://arxiv.org/find/hep-
th/1/au:+Bardeen_W/0/1/0/all/0/1)

Is nature scale invariant? So far the answer is absolutely NO but I strongly
advise to wait and see. There are many topics that point to some breakdown in
scale or reorganizing what we think of space and distance (dualities in string
theory, conformal field theory).

OK, now the important thing I want everyone here to realize. You are living
through a GOLDEN AGE of physics. You wouldn't think that based on what all the
popular magazines tell you. Here's why...

1\. Higgs particle - discovered!

2\. Inflation - discovered! Denying this one is like denying the Big Bang
itself. The evidence is overwhelming and in fact I would list this as the
single greatest scientific discovery of all time. The concurrent discovery of
gravity waves, quantum gravity and a real life example of a Hawking process
only sweetens the deal.

3\. Supersymmetry has basically already been discovered IMHO. They aren't
announcing anything at CERN and won't until they have so many sigmas under
their belt but trust me, it's coming and truth be told, it isn't really so
surprising. SUSY physics has always been rock solid from the beginning. The
situation is very similar to that before offical Higgs announcement and before
someone went knocking on Andre Linde's front door. Many were extremely
confident in the Higgs particle a least a year before the official
announcement. The BICEP 2 results were even more glaringly apparent than the
Higgs results. Many people were walking around the Earth with 'secret
knowledge' that inflation theory was correct even 2 to 3 years before the
official announcement.

So you are living through EXTREMELY interesting times but you wouldn't know it
with all the big science bashing being thrown around.

~~~
angersock
So, erm, what does that buy us?

I'm just an engineer, so I'm not sure I see the utility in any of that--sorry
to sound closed-minded, but am genuinely curious.

~~~
xenophonf
Basic research is the foundation of all engineering. You can't design things
without understanding how the universe works. If you need examples, look no
further than to particle physics, which has had a huge influence on medical
imagery since at least the fluoroscope.

~~~
kazinator
All things hitherto designed have been designed without a complete and
truthful understanding of the universe. If we go back in history, we find
examples of useful inventions that were produced amid a rather poor
understanding. Levers and inclined planes were produced without knowing
anything about basic arithmetic, let alone physics.

------
trhway
>With their field stuck at a nasty impasse

of course. Natural thing when a field is dominated by orthodoxy that closes
their eyes to everything that they don't want to see. Like yesterday
"entangled photon imaging" where what really happens is that a beam modulated
by an image heats/excites crystal (with that heating/excitement thus obviously
modulated by the image) which generates another beam (thus that another beam
is obviously also modulated by the image) which hits CCD - no miracle of
entanglement here, yet Nature published it as such :
[https://news.ycombinator.com/item?id=8234221](https://news.ycombinator.com/item?id=8234221)

as "entanglement" and "mutiverse" are very much in fashion this season and get
you published.

With Higgs as a "mass" boson it was also non-starter because the theory of it
failed to address gravitational and inertial mass equivalence. I mean i don't
doubt that CERN found new particle of course, yet nowhere it was shown that it
is the boson "generating mass". The article seems to suggest that finally the
mainstream physics starts to seriously ponder whether the mass is a result of
dynamic interaction - that has been obvious for decades to the "fringe"
physicists, who couldn't just dismiss the above mentioned gravitational and
inertial mass connection, a pretty fundamental fact that has to be at the
center of anything called physics :)

~~~
l33tbro
I wouldn't say that the "field is dominated by orthodoxy that closes their
eyes to everything that they don't want to see".

I'll admit most physicists I've met are suspicious of wild-eyed theory. But I
wouldn't say they're overly orthodox. I think it's more a healthy skepticism
of anything which involves humans projecting science-ficiton wish-fulfilment
into science.

I'd go further and say that "entanglement" and "multiverse" are not at all en
vogue. I think most seasoned physicists realize that these were trendy fields
some years ago (for solipsistic reasons - ie, make us feel special).

So I think the return to a fundamental assessment of phenomena is pretty
natural thing. Calling out assumptions like scale. What's more, I think the
more discerning will also be suspicious of the "post-multiverse" dialectic.
It's just the process really.

~~~
trhway
>I'll admit most physicists I've met are suspicious of wild-eyed theory.

...

>So I think the return to a fundamental assessment of phenomena is pretty
natural thing. Calling out assumptions like scale.

i see big difference between "Calling out assumptions like scale" as a "return
to a fundamental assessment of phenomena" and "Calling out assumptions like
scale" in order to fit it into a wild-eyed theory like superstrings (basically
to salvage the theory).

------
mSparks
I don't see why this kills the multi verse theory. Which is a basic conclusion
of a 10 dimensional space-time environment that doesn't include mass anyway.

~~~
calinet6
It "kills it" because it's only really appealing if the universe we're in
appears extremely unlikely, like it's the "just right" goldilocks balance of
cosmic variables that we can't explain, that happened to be the stable ones
that resulted in life evolving eventually.

If the universe is actually very likely to occur in the state that it's in,
then we don't need to use this "vast multiverse where our universe was the one
that produced an observer" explanation. It could be a single universe in all
of existence, where everything makes sense mathematically and no further
posturing is required in that silly unscientific field of cosmic philosophy.

Or if it fails, and it remains that our universe is unexpectedly perfect, then
we are forced to resort to statistical explanations within an impossible-to-
observe external multiverse. Scientists don't very much like conclusions built
on not being able to observe things.

Though to me, the multiverse theory has a sort of fractal appeal to it. It is
surely applicable to our planet, after all. Why not our entire universe?

~~~
clusterfoo
Naive question (I know nothing about this stuff):

If mathematical logic is a property of our universe, then aren't we again
entering the realm of circular logic? i.e: "Given the logical frameworks that
are correct in our universe, our universe is very likely."

Unless math is something that somehow exists independently of our physical
universe... but then "where" does it come from?

~~~
calinet6
I have no idea, really.

My hunch is that mathematics is more than universal; truths hold regardless of
which medium of calculation is used to conclude them.

In any case, our conclusions about our own universe at least hold within our
own universe, and are therefore still very useful for our own understanding
thereof.

------
JackC
For a heroic attempt to explain this article to laypeople, check out
physicsmatt's comments over at Metafilter:

"First, for maximum sense-making, read my previous comments here, here, here,
and here. I realize that's a lot, sorry. The Universe is complicated. Then,
for what follows, recall that to a particle physicist such as myself, there is
no difference between lengths and energies (or indeed, any other dimensional
quantity). Length is inverse energy: very energetic phenomenon probe very
small lengths ...."

[https://www.metafilter.com/142211/Multiverse-No-More-a-
New-T...](https://www.metafilter.com/142211/Multiverse-No-More-a-New-Theory-
of-Scale#5703172)

~~~
antimagic
Or don't - it's incredibly badly written, in the sense that it often descends
into grammatical gibberish, even without worrying about the physics the
gibberish is trying to describe.

~~~
calinet6
There's really not that much to understand, and the details aren't that
important unless you're living them.

The question boils down to this: are we one of an infinite number of universes
that popped into existence that just happened to have the right variables to
be stable and result in life? (The anthropic principle, a statistical
conclusion, and a philosophical mind-bender...)

Or are we in a single universe whose properties are mathematically aligned in
such a way as to be very unlikely to result from chance, even if repeated an
infinite number of times? The details of this are interesting, but extremely
numerous and complex: basically, Physicists are trying everything.

The latter does not require the hand-wavey wishy-washy existence of an
infinite number of non-observable extremely large things, and therefore
garners more enthusiasm.

However, if observations conclude that the parameters of our universe are in
fact paradoxically perfect, then the idea that we're an evolved observer of
one chance universe out of many holds water.

Hence the intense research on how this whole universe thing works. Fun.

------
playing_colours
When I became interested in modern physics theories of both quantum and
universe level, I found the following book [0] by Max Tegmark to have very
good explanations regarding origin and nature of the universe, quantum
mechanics, and just interesting stories / facts from the life of physicists.

[0] [http://www.amazon.com/Our-Mathematical-Universe-Ultimate-
Rea...](http://www.amazon.com/Our-Mathematical-Universe-Ultimate-Reality-
ebook/dp/B00DXKJ2DA/ref=sr_1_1?ie=UTF8&qid=1409321567&sr=8-1&keywords=our+mathematical+universe)

------
pablisco
"Radical New" and "Theory" doesn't make sense, surely this would be a
hypothesis :)

------
kazinator
> "Multiverse ennui cannot last forever" says Graham Ross?

That is naive. There is no way to prove or disprove it; it can be safely
regarded as true without ever contradicting any possible observation we can
ever make.

I do not think physics will ever settle the questions in such a way that the
"multiverse ennui" is not invoked to cover the loose ends; in fact, it will
become more and more obvious as the inescapable conclusion.

The deeper we dig into nature, either we keep finding more mathematics, or we
encounter some absolute that can no longer be analyzed.

Once we know every physical law, and are certain nothing more is to be
discovered, how do we distinguish our universe from a set of mathematical
axioms? We have two choices then: to suspect there is some outer universe
which implements the rules and axioms of this one. Or else admit that axioms
do not require an implementation: they just are, and that's what makes their
system exist (which means that any other axioms and rules we can imagine also
exist just as much).

Either hypothesis is an unprovable "cop out"; but the latter of the two is
more plausible. The first hypothesis still leads to an infinity of universes,
and they have to be nested in each other in an infinitely regressing sequence.
The second one has no such silly requirement; and it has the anthropic
principle which plausibly explains everything that seems arbitrary or special.

------
dlevine
To be fair, this only kills one of the multiverse hypotheses. I'm reading
Brian Greene's "The Hidden Reality" right now, and he describes about 8
independent (or semi-independent) multiverse hypotheses. From what I
understand (and I'm no physicist), this just provides evidence against the
anthropic principle, and the multiverse associated with that line of
thinking...

------
3rd3
Someone in the comment section claims plagiarism. What's that all about?

[http://www.wired.com/2014/08/multiverse#comment-1560643455](http://www.wired.com/2014/08/multiverse#comment-1560643455)

Edit: Never mind,
[http://rationalwiki.org/wiki/Mensur_Omerbashich](http://rationalwiki.org/wiki/Mensur_Omerbashich)

------
Natsu
Things like this keep me wondering if eventually we will reach a point where
we are unable to distinguish theories about our own past due to lacking the
energy necessary to experiment with those conditions thanks to entropy.

~~~
vecter
What does entropy have to do with anything?

~~~
dspillett
If the available energy is dispersed and chaotic, we won't be able to
concentrate enough to perform the experiments? Though I doubt that'll be the
case at any time while the human race is in existence...

(caveat: I know very little of real physics)

~~~
Drakim
If humanity lives to a point where entropy becomes a problem, I'm pretty sure
our lives would be the first to go, not our "ability to perform experiments".

~~~
serf
that entirely depends on the magnitude of the experiment.

If we were approaching any "universal energy" limitations, it'd stand to
reason that our technology would be very much different than our technology
now -- perhaps universe sized experiments would be feasible by that point, at
which time we may hit a limit imposed on us not by anything other than the
length of time since the last universe formation event, and our poor luck in
meeting that point in technology at a time where the energy no longer exists
to fuel it.

Unlikely, and I think your idea of life being threatened before science is
probably much more rational, but it's fun to think about. Plus, if we were
using that much energy for a single experiment, one would wonder about that
experiments' safety.

------
ccvannorman
I once read that "black holes orbiting each other follow the exact same
mathematics as electrons orbiting protons", but I was unable to find the
direct source. I did find another article comparing black holes to elementary
particles:

[http://www.technologyreview.com/view/413483/could-all-
partic...](http://www.technologyreview.com/view/413483/could-all-particles-be-
mini-black-holes/)

~~~
Bognar
They would naturally follow the same mathematics, since the formula for
gravitational attraction and the formula for electrical attraction are both
following the inverse square law.

[http://en.wikipedia.org/wiki/Inverse-
square_law](http://en.wikipedia.org/wiki/Inverse-square_law)

------
hcarvalhoalves
> Perhaps the fundamental description of the universe does not include the
> concepts of “mass” and “length,” implying that at its core, nature lacks a
> sense of scale. This little-explored idea, known as scale symmetry, (...)

Isn't the word for that _fractal_?

~~~
andrewflnr
Ah, no, that's a completely different sense of scale invariance. In a fractal
you still have to measure the sizes of different similar structures, and
generally pay attention to length. It seems that this article is discussing a
much deeper abandonment of length.

------
kazinator
WOBAD!

[http://www.theonion.com/articles/worlds-top-scientists-
ponde...](http://www.theonion.com/articles/worlds-top-scientists-ponder-what-
if-the-whole-uni,712/)

~~~
kimdouglasmason
From the article:

 _" That shit would be too much," Gupta said. "It'd be like that Dr. Seuss
book Horton Hears A Who and shit. I read that when I was, like, six, and it
totally weirded me out."_

Nailed it.

------
teh_klev
Original article with less visual crap around the sides:

[http://www.simonsfoundation.org/quanta/20140818-at-
multivers...](http://www.simonsfoundation.org/quanta/20140818-at-multiverse-
impasse-a-new-theory-of-scale/)

~~~
bellerocky
Better and it doesn't have a link bait title.

------
notastartup
Feels like I'm a kid and I've just been told Santa Claus is made up.

~~~
coldtea
Actually it should feel more like a tall story from your uncle at a family
dinner, that's not corroborated and doesn't even imply what he insists it
implies.

That is, half of the article is trash and the other doesn't represent the
science correctly.

------
itry
"size differences are illusory"

So two things standing next to each other are the same size as one thing
alone?

Damn hard to imagine. I would think "size" does not really "exist" but is a
man made concept. And by its definition, two things next to each other form a
"bigger" thing.

~~~
coldtea
The article is badly written, but it doesn't really mean sizes are illusory
(even if it says so at the beginning). It goes on to say that sizes and mass
"spontaneously emerge" from lower interactions, which is to say, they become
real for us.

But, to address your example: "So two things standing next to each other are
the same size as one thing alone? Damn hard to imagine".

That might not hold for size, but a very similar thing does occur (and is
proven) for speed.

If you are in a car that goes at 0.8 miles per minute, and you throw a dart
that goes at 0.3 miles/minute, its speed is 1.1 miles/minute (the sum).

But if you travel at the 0.8x the speed of light and you throw something
forward at 0.3x the speed of light, its speed is not 1.1x the speed of light,
but c. That is, trying to add velocity doesn't get you faster than the speed
of light.

[http://curious.astro.cornell.edu/question.php?number=145](http://curious.astro.cornell.edu/question.php?number=145)

~~~
lutusp
> But if you travel at the 0.8x the speed of light and you throw something
> forward at 0.3x the speed of light, its speed is not 1.1x the speed of
> light, but c.

Not really. Velocities near c don't sum that way. And your reference doesn't
support your claim.

~~~
gus_massa
I agree. More details: [http://en.wikipedia.org/wiki/Velocity-
addition_formula](http://en.wikipedia.org/wiki/Velocity-addition_formula)

If you add two velocities that are less than c, you can never get c, you
always get something smaller.

0.8c + 0.3 c ~= 0.887 c (It's smaller than c)

At low speeds the effect still exists, but it's negligible. There is an
important difference between "it doesn't exist" and "it's so small that if we
forget it we will be fine".

It's so small that you must use floating point numbers with too many digits to
calculate it. It's more useful to calculate the difference between the
"relativistic" sum and the "classical" sum. Another way is to aproximate the
formula with a Taylor expansion

dif = (X+Y) / (1+(X * Y/c^2)) - (X+Y) ~= - (X + Y) (X * Y/c^2)

0.8mph + 0.3 mph = 11mph - 5.9 * 10^-39 mph

The correction is veeeeery small.

~~~
lutusp
> The correction is veeeeery small.

Indeed it is. The only place I can think where such a small correction matters
is in the GPS system. The accuracy of the GPS system depends on tracking down
and eliminating every possible source of error, and to maximize position
accuracy, two relativistic effects are accounted for:

1\. The time dilation caused by the satellites' velocity, from Special
Relativity.

2\. The rate of time passage at orbital altitude compared to that at the
surface, which reflects the gravitational well effect of General Relativity.

The two effects move in opposite directions, but they don't cancel out. The
applied correction (to the orbiting clocks) is very small indeed, but enough
to avoid a gradual but serious decline in positional accuracy over time.

~~~
xrange
Does anyone know of a general & special relativity simulator? That is, a
program where I can setup various "thought experiments", by placing clocks and
masses at various point in space, where they can have various acceleration
profiles, and can communicate with each other, and run the scenarios? I never
really understood the twins "paradox" and the explanations for the source of
the asymmetry seemed hand-wavy and "because".

