I’m in the middle of jetting hither and yon, talking to people about the arrow of time. (Wouldn’t it be great if I had a book to sell them?) Right now, as prophesyed, I’m at the Quantum To Cosmos Festival at the Perimeter Institute. They’re extremely on the ball over here, so every event is being recorded by the ultra-professional folks at TVO, and instantly available on the web. So here is the talk I gave on Saturday night — a public-level discussion of entropy and how it connects to the history of our universe.
Yes, that’s a pretty suave picture of me on the image capture. What can I say? I’m just one of those lucky folks with an effortless magic in front of the camera.
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If you prefer to get your talks about entropy unadulterated by voice and motion, and don’t mind a more technical presentation, I’ve put the slides from my recent Caltech colloquium online. These are aimed basically at grad students in physics, so there is an equation or two, and the caveats are spelled out more clearly. But the punchline is the same.
Are you trying to wring somebody’s neck? Perhaps an errant graduate student’s?
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Sean, as a logician interested in theoretical physics, I can’t buy your argument toward laymen about the cosmological arrow of time.
That if I can do omelet from eggs and not eggs from omelet is due to the conditions of the big bang is, IMOH, at least ludicrous, at most hilarious!
The arrow of time is a local thing that has to do with our idea of causation, and more profoundly the forgetting of initial conditions. I believe this is all an illusion made by the way our neurochemistry of memory is linked to forgetting initial conditions, not to the whole history of the universe, which, from this point of view, makes non sense.
I recently read on the Arxiv a paper explaining that appearance are OK with the Big Bang why a deeper understanding rules it out as an illusion of the way we memorize events, and I agree with that.
I stand that thermodynamics’s second law and all this stuff about time arrow are related to a geometrical view of time which is just an appearance hiding a more fundamental timeless universe, and that your writings, while interesting, are really a naive common approach on the subject…
Every time I think about the topic I can’t help but feel that something is wrong. Something (several things, actually) seems to be at odds with reality at microscopic patches of the universe, like ours. Trying to explain early states is one issue, but I believe certain things are being looked over that will leave us even worse off than worrying about a single singularity. Time, irreversability of quantum processes, inexplicable information growth in some regions… I know this is probably not the right thing to say to a cosmologist, but perhaps a fine-grained approach is more likely to reveal what is going on.
It is irk-some how physicists incorrectly use isometry and unitarity interchangeably when working with infinite dimensional spaces.
While every unitary operator is an isometry, not every isometry is unitary. Furthemore the sufficient condition for an evolution operator to be conservative is that it is an isometry, not a unitary operator. The shift operator on functions with a lower bounded domain is a perfect example of an isometry that is not unitary. By definition a unitary operator is a bijective isometry. This point is hammered home in any introduction to functional analysis course, see JB. Conway, A Course in Functional Analysis, for example, I think it is around page 35.
So if you assume a lower bound for time, then by definition, forward translation through time is not unitary, but it is an isometry; and reverse translation is neither since it has a non-trivial kernal.
Here are some basic definitions straight from the referenced text book; using standard inner product notation
A is an isometry iff (Ax,Ay)=(x,y) for all x,y in the space H
A is unitary iff A is an isometry and H/cl(Im(A))={0}
The definitions are equivalent on finite dimensional vector spaces, but not so in infinite dimensional spaces. The tricky bit is that you can stick an infinite dimensional space inside of itself without losing any dimensions. The equivalent is not possible in finite dimensions.
An example of this logic is the infinite hotel: consider an infinite hotel that has been filled to capacity. Now suppose an infinite number of new guests show up. What do you do? You ask the current guests to move the the even number rooms and put the new guests in the odd number rooms.
Time flies like an arrow, fruit flies like a bananananana. (I never know when to stop.)
Just to set the scene, I and a few other astronomy graduate students made the drive up from Toronto to see the talk. We were made to stand outside in a “rush” line (although the event was free), and when the time finally came to let us in when it got to us there were no seats left! Amazing, it is a big auditorium! So we were sent to the fourth floor to watch on a big screen, which was very nice of them, I expected to simply be turned away. Great show in the end, we all enjoyed the talk. If only all outreach could be this well done.
AIEE…THAT SHIRT…MY EYES! MY EYES!!!
Nice talk. I liked the way you clearly cordoned off what is known from what is speculation. The public needs to know that some wild-sounding things they hear are actually true, even if a lot of them are just guesswork. My only objection would be including “the illusion of free will is due to the arrow of time” as known (although this may have been inadvertent).
Anybody who gives public lectures or volunteers could learn a lot from your choices and delivery.
If you want to increase the entropy in your slides, change the “entropoy” in the first paragraph of slide 13 to “entropy”. Could there be a cosmic proofreader who creates more entropy out of typos and misspellings?
BTW, it’s a good set of slides and an interesting idea. It makes me think that the universe is decompressing, in the sense of data decompression, as it grows.
Loved the slides, and the increasingly spiked graphical representations of the universe were especially intriguing. What a shame one can’t readily justify a sudden runaway espansion at some point in the distant future, so the spikes would abruptly flatten out into a plane at the base and start looking like Dirac delta functions! If one could assemble enough of those constantly reforming and dissipating in the right way, it would begin resembling a wave function wouldn’t it, albeit on an unimaginably vast scale?
Are physicists certain about that damned minimum limiting cosmic temperature of 10^-30K or whatever it was you mentioned the other day? This is the only obstacle to all black holes (of mass greater than one of that temperature) eventually evaporating. It seems vaguely plausible their presence is all that prevents a final “great rip”, but this could and would occur as they evaporated.
Could you elaborate on black hole evaporation. Specifically, couldn’t the dissipation of energy from the black hole lead to the black hole losing enough mass to no longer being a black hole, or does the rate of dissipation somehow not change the density?
Is it possible that a black hole could become dense enough to spawn a baby universe instead of it being caused by fluctuation in vacuum energy? This would remove the mass/energy from the parent universe and thus making the parent universe a non-closed system.
@12 Jean, a physicist called John Baez has a good page on this titled The End of the Universe
I was sketching a picture of not just our universe (in the conventional causally connected sense) but a whole throng of them each going through its life cycle, as depicted on a couple of Sean’s slides, such that if suitably coordinated in some higher dimensional space then the overall effect could resemble a wave function, rather like a swarm of flashing fire flies.
This is based on the idea of wave functions in configuration space being capable of construction by integrals involving Dirac Delta functions and, who knows, perhaps these formal artifacts also represent the limit of a physical process at the smallest Planckian scales, with energy comprising similar spikes which dissipate in the shortest possible time but somehow constantly regenerate, to conserve energy as we observe it. This might explain the well-known perplexing 10^120 factor of missing vacuum energy – all just dissipated to a completely unobservable uniform background “ocean”.
It would be a pleasing symmetry if the very smallest conceivable phenomena worked exactly the same way as the largest and, who knows, perhaps these Planckian energy spikes, if they exist, are universes in themselves, and perhaps our universe is no more than one of them, lasting a mere instant, in countless others!
Drat, I only meant to post the Baez reference, but was carried away! đ
Hi Sean,
An interesting lecture, one which if Iâd have had the time would have liked to have attended physically, rather than virtually, had it not been for my accursed work schedule. Itâs also interesting that both you and Lee Smolin are having your books being brought out at about the same time in regards to the subject. When I have a chance I will have no choice other than to pick both of them up, as to compare the similarities and differences. The only problem is in finding the time to read them. If you either of you where to discover a way to provide some of this, along with the book, I could almost guaranty they to become best sellers đ
Best,
Phil
The Source of the Universe. / My interpretation./
=== .
What was before Vacuum or Gravity ?
Does Gravity exist in Vacuum or vice versa?
What is the First Law of the Universe: Vacuum or Gravity ?
In my opinion the Universe ( as a whole ) is Eternal and
Infinite Vacuum an Absolute Reference Frame .
Why ?
== .
Fact and Speculation.
1.
Fact.
The detected material mass of the matter in the Universe is so small
(the average density of all substance in the Universe is approximately
p=10^-30 g/sm^3) that it cannot âcloseâ the Universe into sphere and
therefore our Universe as whole is âopenâ, endless Vacuum.
But what to do with the infinite Universe the physicists don’t know.
The concept of infinite/ eternal means nothing
to a scientists. They do not understand how they could
draw any real, concrete conclusions from this characteristic.
A notions of âmore, less, equally, similar â could not
be conformed to a word infinity or eternity.
The Infinity / Eternity is something, that has no borders,
has no discontinuity; it could not be compared to anything.
Considering so, scientists came to conclusion that the
infinity/eternity defies to a physical and mathematical definition
and cannot be considered in real processes.
Therefore they have proclaimed the strict requirement
(on a level of censor of the law):
« If we want that the theory would be correct,
the infinity/eternity should be eliminated » .
Thus they direct all their mathematical abilities,
all intellectual energy to the elimination of infinity.
Therefore they invented an abstract âdark matter and dark energyâ.
They say: â 90% or more of the matter in the Universe is unseen.â
And nobody knows what it is.
2.
Speculation.
Unknown âdark matter â it is matter which makes up the difference
between observed mass of a galaxies and calculated massâŠâŠ
whichâŠ.will âŠâclose â âŠ.the Universe into sphere, as âŠâŠ.
asâŠâŠthe astrophysicists want.
Question:
How can the 99% of the Hidden ( dark ) matter in the Universe
create the 1% of the Visible matter ?
========================== . .
#
Now it is considered that Newton / Einstein’s laws
of gravitation are basis of physics, the first laws of Universe.
But the detected material mass of the matter in the Universe
is so small that gravitation field, as whole, doesn’t work
in the Universe.
So, the Newton / Einstein’s laws of gravitation are correct only
in the small and local part of Universe and we cannot take them
as the first ones.
What can the first law of the Universe be?
All galaxies , all gravitation fields exist in Vacuum (T=0K).
Gravitational effects took place only in a small area of Infinite Vacuum.
It is impossible to use GRT to the Universe as a whole.
Vacuum is â The first law of the Universe.â
The Physics is first of all Vacuum.
Without Eternal and Infinite Vacuum Physics makes no sense.
=== .
Best wishes.
Israel Sadovnik. / Socratus.
http://www.worldnpa.org/php2/index.php?tab0=Scientists&tab1=Display&id=1372
================== . .
Time and Quantum of Light. / My opinion./
Can Time Exist Without Matter?
1.
According to Newton the answer is â Yesâ.
2.
According to SRT and GRT the answer is â Noâ.
3.
Who is right? Who is wrong?
What is the resolution of this apparent paradox?
===========================..
There are two kinds of time:
a) the proper (individual) time and
b) the planetary time.
They are so familiar that we rarely give them thought.
Donât we know, that time for living being is limited
and the planetary time is absolute for them ? It is.
Maybe therefore Newton declared that time is absolute.
It â flows equably without relation to anything externalâ
he wrote in 1687. But Einstein had another opinion.
He wanted to know: â Where does the conception of time
come from?â, â What is the essence of time?â.
And to explain these questions he created two theories:
SRT and GRT and declared that time is relative, changeable.
1.
SRT explains behavior and the proper time of light
quanta /electron. Why do I think so?
a)
One law (postulate) of SRT says that speed of light quanta
is constant c=1. Second law ( postulate ) says no another particle
can reach this speed. So there are two incommensurable
quantities. Is it possible to bind them together? No. I was
taught at school from the first class that the incommensurable
quantities cannot be compared. The connection between these
incommensurable quantities is similar to the decision of a
problem: âWhat will be if the whale attacks the elephant?â
We can see whale in a ocean and elephant in a savanna,
but they never meet and fight in the same â frame of referenceâ.
And the same is about light quanta and another particles.
We cannot see them together in SRT. We can meet only the
light quanta in SRT and no other particles in it.
b)
SRT was born from Maxwell’s theory and it is a continuation
of the electrodynamicsâ development . The electron is a main
and single hero in the Maxwell’s theory and SRT. There
isn’t the Maxwell’s theory / SRT without electron.
It is not correct to compare electron/ light quanta with another
particles (protonsâŠetc) and bodies (billiard balls, satellites,
astronauts, âtwinsâ) because they cannot produce electromagnetic
fields. The electron and the another particles are also incommensurable
quantities. They are absolutely different objects.
c)
Every epoch has its own delusion. Maxwell and Boltzmann
tried to explain electromagnetic fields using balls, wheels,
cog-wheels, springsâŠetc. H. Hertz, who demonstrated the
existence of the electromagnetic waves, wrote that the
electromagnetic waves didnât have practice use. EtcâŠ.
Now we try to compare electron/photon
ability with astronautâs and âtwinsâ â opportunities.
It is mistaken, but what to do? We do it because this is
our way of cognition:
â From vague wish to the bright thoughtâ.
2.
So, how SRT explains time from electron/ light quanta point of view.
a)
When light quanta is in state of a rest its time is frozen,
and its own clock shows zero.
b)
When photon moves with constant speed c=1
its time is also frozen, and its own clock still shows zero.
c)
Only when photon moves with speed c>1 its zero time
changes and limited time appears. In this situation we
know photon as an electron. Photon works as an electron
and SRT and Lorentz transformations explain this process.
d)
And when , for example, electron emits from an atom and
interacts with Vacuum all its parameters change. Its limited
time ends and its own clock shows zero again. Now it lives
in infinite/ eternal Vacuum until new incarnation, until its new
work, maybe, in an atom (molecule), or in a cell, maybe, in a blade
of grass or in a tree, maybe, in an animal or in a person.
In another words:â We are living beings until Light quanta/
Electron is present and works in our body.â
Is it true? Yes, it is true. Why?
Because W. Pauli in 1924 wrote:” Each quantum state in the atom
is not limited of two electrons, but only one electron”.
It means in the atom can be only one, single electron.
The electron manages the atom. If the atom contains more
than one electron (for example â two), this atom represents
â Siamese twinsâ. Save us God of having such atoms and cells.
And the living being begins its life from one, singe cell.
What I am introducing here is what ‘ thinking photon/ electron’ exist .
I applied the quantum of light/ photon/ electron with a consciousness.
And His own consciousness is not static but can develop.
The development of conscious scale goes
” from vague wishes up to a clear thought “.
This evolution proceeds during hundred millions (billion) years.
e)
Trying to understand â the electrodynamics of moving bodiesâ
Einstein wrote that it is the result of time and space changes.
It is not exactly correct , because these changes are secondary
in SRT. And the first point of SRT is that Quantum of light changes
its spin. The former Planck/ Einsteinâs spin (h) changes in Goudsmit /
Uhlenbeck’s spin (h = h / 2pi), and as a result of this act all its parameters
change and the time and new space appear.
3.
GRT explains the conditions of gravitation and the secret of
planetary time. Why do I think so?
a)
When Einstein worked on GRT, he asked astronomers:
â What is the average mass of matter in the Universe?â
The result was lamentable. The quantity of mass was
insignificantly small. It was impossible to keep gravitation
law with such insignificantly little mass and so, the Universe
must be âopenâ, endless. But what to do with the infinite
space, Einstein didnât know. Therefore he took (from the
heaven) â the cosmological constantâ in order to âcloseâ
the Universe. The taken mass was enough for creating the
condition of gravitation. Without â the cosmological constantâ
the Universe is endless.
b)
In 1922 Friedman wrote, that we could not take â the
cosmological constantâ in calculation. Instead of it, it is
enough to take âtimeâ and the Universe will be âclosedâ.
Friedman was correct, but why? Because âtimeâ, by its
nature, is a limited physical quantity and, be taken in
mathematical calculation, automatically gives âclosedâ result.
c)
So, the detected material mass of the
matter in the Universe is so small (the average density
of all substance in the Universe is approximately
p=10^-30 g/sm^3) that the gravitation law doesn’t work.
Astronomers and astrophysicists know about this fact and
therefore (to save the gravitation law) invented new matter
a “dark matter”, a new energy a âdark energyâ and another
abstract objects. This â inventionâ is only a result of our
mentality , which says: â If in a theory you meet infinity it
means the theory is nonsenseâ. It is very hard to take that
the Universe is infinite. It is no easy matter to give up
a lifetime of habit .
d)
On my opinion it is impossible to use GRT to Universe as
a whole. The Newton/ Einstein’s gravitation laws are correct
only in the local parts of Vacuum. The Universe / Vacuum
as a whole is endless.
e)
So, how does GRT explain time?
According to GRT the time depends on the mass
and speed it means, of moving matter.
It means that different masses and speeds can create
different time. For example, our planet Earth has its
own time but for us it is absolute.
The other planets have another mass and speed and
therefore they have their own time. This time according
to GRT is relative. But their habitants will think that their
time is absolute. But if they know GRT they will
not make this mistake.
=============
According to SRT and GRT time is relative.
SRT says about proper/ individual time of an
electron/ light quanta.
GRT says about planetary time of a Planet..
The time cannot exist without matter and speed,
in another words, without moving matter. But
different reasons and different moving of a matter
create the proper and planetary time.
==========.
Best wishes.
Israel Sadovnik. / Socratus.
http://www.physforum.com/index.php?showtopic=23624&st=15
http://www.physforum.com/index.php?showtopic=2547&st=105
http://www.physforum.com/index.php?showtopic=2548
================== . .
All of the black holes must be feeding energy into the big bang through negative time, making a complete cycle, free of singularities.
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