Thursday, November 21, 2013

The five questions that keep physicists up at night

Image: Leah Saulnier.

The internet loves lists, among them the lists with questions that allegedly keep physicists up at night. Most recently I spotted one at SciAm blogs, About.com has one, sometimes it’s five questions, sometimes seven, nine, or eleven, and Wikipedia excels in listing everything that you can put a question mark behind. The topics slightly vary, but they have one thing in common: They’re not the questions that keep me up at night.

The questions that presently keep me up are “Where is the walnut?” or “Are the street lights still on?” I used to get up at night to look up an equation, now I get up to look for the yellow towel, the wooden memory piece with the ski on it, the one-eyed duck, the bunny’s ear, the “white thing”, the “red thing”, and various other household items that the kids Will Not Sleep Without.

But I understand of course that the headline is about physics questions...

The physics questions that keep me up at night are typically project-related. “Where did that minus go?” is for example always high on the list. Others might be “Where is the branch cut?”, “Why did I not run the scheduled backup?”, “Should I resend this email?” or “How do I shrink this text to 5 pages?”, for just to mention a few of my daily life worries.

But I understand of course that the headline is about the big, big physics questions...

And yes, there are a few of these that keep coming back and haunt me. Still they’re not the ones I find on these lists. What you find on the lists in SciAm and NewScientist could be more aptly summarized as “The 5 questions most discussed on physics conferences”. They’re important questions. But it’s unfortunate how the lists suggest physicists all more or less have the same interests and think about the same five questions.

So I thought I’d add my own five questions.

Questions that really bother me are the ones where I’m not sure how to even ask the question. If a problem is clear-cut and well-defined it’s a daylight question - a question that can be attacked by known methods, the way we were taught to do our job. “What’s the microscopic origin of dark matter?” or “Is it possible to detect a graviton?” are daylight questions that we can play with during work hours and write papers about.

And then there are the night-time questions.
  • Is the time-evolution of the universe deterministic, indeterministic or neither?

    How can we find out? Can we at all? And, based on this, is free will an illusion? This question doesn’t really fall into any particular research area in physics as it concerns the way we formulate the laws of nature in general. It is probably closest to the foundations of quantum mechanics, or at least that’s where it gets most sympathy.
  • Does the past exist in the same way as the present? Does the future?

    Does a younger version of yourself still exist, just that you’re not able to communicate with him (her), or is there something special about the present moment? The relevance of this question (as Lee elaborated on in his recent book) stems from the fact that none of our present descriptions of nature assigns any special property to the ever-changing present. I would argue this question is closest to quantum gravity since it can’t be addressed without knowing what space and time fundamentally are.
  • Is mathematics the best way to model nature? Are there systems that cannot be described by mathematics?

    I blame Max Tegmark for this question. I’m not a Platonist and don’t believe that nature ultimately is mathematics. I don’t believe this because it doesn’t seem likely that the description of nature that humans discovered just yesterday would be the ultimate one. But if it’s not then what is the difference between mathematics and reality? Is there anything better? If so, what? If not, what does this mean for science?
  • Does a theory of everything exist and can it be used, in practice (!), to derive the laws of nature for all emergent quantities?

    If so, will science come to an end? If not, are there properties of nature that cannot be understood or even modeled by any conscious being? Are there cases of strong emergence? Can we use science to understand the evolution of life, the development of complex systems, and will we be able to tell how consciousness will develop from here on?
  • What is the origin and fate of the universe and does it depend on the existence of other universes?

    That’s the question from my list you are most likely to find on any ‘big questions of physics’ list. It lies on the intersection of cosmology and quantum gravity. Dark matter, dark energy, black holes, inflation and eternal inflation, the nature and existence of space-time singularities all play a role to understand the evolution of the universe.
(It's not an ordered list because it's not always the same question that occupies my mind.)

I saw that Ashutosh Jogalekar at SciAm blogs also was inspired to add his own five mysteries to the recent SciAm list. If you want to put up your own list, you can post the link in this comment section, I will wave it through the spam filter.

55 comments:

Vijay.Strings said...

Madam,

I think all four questions are embedded in this important one.

What is the difference between Mathematics and Reality?
If we can pursue this one, I believe it will help a great deal to take of other four.

Do you agree with me?

Best,
Vijay

Sabine Hossenfelder said...

No, I don't agree. Because if there is no difference between mathematics and reality, the other four questions are still standing.

Greg Sivco said...

Interesting questions. Some we will never know. Will give my best interpretation one at a time:

Greg Sivco said...

1) Both, depending on length scale.
2) Yes. No.
3) Yes. No.
4) No.
5) The big question. Shrug. Do not know, but an intelligent guess:
There was time before time and two fifth dimensional universes connected and we are at the venturi, hence a constant speed of light. Our fate? Don't know, can't, until we get there.

Uncle Al said...

1) Deterministic time evolution demands the deity who gave Semites their awful calendars.
2) An accessible past contradicts the one we suffer now.
3) Reality does not crunch numbers . However, predictive analog models are excuses not understanding (but useful).
4) There is no tractable theory of everything, for then the universe would lack future Otto Sterns empirically pissing on future Dirac equations' predicted proton magnetic moments.
5) 42. Having the answer may not specify the question.

1) Are photon vacuum symmetries exactly matter vacuum symmetries? Do visually and chemically identical, enantiomorphic space group alpha-quartz single crystal pairs violate the Equivalence Principle?
2) If one laid a string of 600 messages in bottles north to south across the Antarctic Circumpolar Current, where would each end up?
3) Does a 2:1 mixture of (1S,4S)- and (1R,4R)- camphor, when matter-diffracted, change its enantiomeric excess? What happens to semibullvalene if its grating traversal time exceeds its degenerate Cope rearrangement time?
4) Photosynthesis is free radical chemistry. Grow Arabidopsis thaliana in the bore of 9 tesla Oxford, Bruker, or LHC supercon magnet to ding it.
5) Do William Little's exciton supercons work, now that we can trivially synthesize the polymers? Phonons' Deby temperature coupling goes soft below 35 K. Excitons' ~2 eV coupling goes soft around 23,000 K. Theory says Little is crap. Go Otto Stern on theory.

Uncle Al said...
This comment has been removed by the author.
Uncle Al said...
This comment has been removed by the author.
Arun said...

If some aspects of the universe are well described by cellular automata, would you consider that as part of mathematics or as a different type of description?

Sabine Hossenfelder said...

Arun,

Depends on exactly what you mean with this. If you mean well described by the algorithm of cellular automata, I would consider this part of mathematics. If you mean well described by a simulation run on a computer (an actual, physical "thing"), I would consider this potentially a different type of description (depending on whether or not the computer is a mathematical "thing" too). Best,

B.

Wes Hansen said...

Questions One, Two, and Five seem to be all related; Does the Universe have a definite final boundary condition? If so then the Universe would seem Chaotically Deterministic but one would have to account for backward causation. Could this be accomplished by relaxing symmetry constraints to bi-simulation?

Sabine Hossenfelder said...

Yes, in my mind it's all related...

Zephir said...

The most important questions for physicists today should be these ones important from practical perspective (cold fusion, magnetic motors, antigravity drives) - just after then some abstract stuff, which cannot move the progress forward anyway. The logics is simple: the physicists are payed to help the rest of society, not vice-versa.

vmarko said...

Hi Bee,

The questions you pose are apparently more related to philosophy than to physics, IMHO... :-)

That said, I am a little surprised with some of the questions, since it seems that they have pretty plausible answers. In particular,

"Are there systems that cannot be described by mathematics?"

Sure there are. For example, the dynamics of human emotions is hopelessly beyond any mathematical description. Also, the qualia stuff, perception of the color red, etc.

"Does a theory of everything exist"

Of course it doesn't, Goedel's incompleteness theorems should have settled that question already. The only thing that can exist is a "theory of everything so far", where we keep an open door for additional new axioms as they are needed.

"and can it be used, in practice (!), to derive the laws of nature for all emergent quantities?"

No, it cannot. Chaos theory puts a strong limit on the idea of reductionism (at least in practice!), and complexity can always hide phenomena which are qualitatively different. Additional axioms for your TOE will always exist, in Goedel-speak.

I also have my personal candidate answers to your questions 1, 2 and 5, but I admit that there are multiple possibilities to answer those...

So, did I misunderstand your questions 3 and 4, or is there something else that I'm missing here?

Best, :-)
Marko

vmarko said...

Ok, after "friendly criticizing" your questions, maybe it is only fair that I also put out a couple of questions of my own, that keep me awake at night...

(1) Why is nature local? // i.e. why is there a preferred basis in orbital Hilbert space, such that interactions are local when represented in that basis? //

(2) Can QM be formulated without the concept of probability? // there is only one universe, so when doing quantum cosmology we cannot construct a quantum state by taking an ensamble of N->oo identical copies of our system. You can do it with electrons, but not with universes... //

(3) Does third quantization make sense? // i.e. should we sum over different spacetime topologies in a QG path integral; should we allow for quantum transition amplitudes from one topology to another; can such transitions be measured, even in principle? //

(4) What are fundamental degrees of freedom for gravity? // i.e. the concept of a manifold should be exchanged for some other structure, but which one? IOW, what is the correct UV completion of QG? //

(5) Is there a solution to the measurement problem? // i.e. is the wavefunction collapse ultimately objective or not, and why? //

There are also non-physics questions that keep me awake, but those are off-topic here... :-)

Best, :-)
Marko

DocG said...

"Does the past exist in the same way as the present? Does the future?"

This might be helpful.

In the past, the present existed in the future.

In the future, it will exist in the past.

So if the present moment moves from the future to the past, then time moves from the future to the past, no?

On the other hand, time must move from the past to the future, because the past existed in the past and the future will exist in the future.

What this tells us is that there is no arrow of time. What it also tells us is that time cannot be fundamental, but must be an emergent property of something more fundamental.

What that fundamental thing is is stasis. Time "moves" as a figure against the background of stasis.

Now you can go back to sleep, Bee.

Chris Kennedy said...

It's a good thing they had some Arabidopsis thaliana in that scene in Avatar. It helped me navigate my way through the darkened movie theater.

Florin Moldoveanu said...

"What is the difference between Mathematics and Reality?
If we can pursue this one, I believe it will help a great deal to take of other four."

Now this question kept me up at night for the past 4 years.

I'll write some posts about it in a few weeks at my blog: http://fmoldove.blogspot.com/

Robert L. Oldershaw said...

Can't resist.

1. Deterministic (in NLDS sense).

2. Past 'in the can' (cannot go backwards or change); future created in present (ala Ellis).

3.Yes, but need some concepts too; yes (e.g., evolutionary principles).

4. Yes, but math does not permit exact solutions, all solutions are approximations with a wide range of accuracies; yes.

5. No ex nihilo creation, more like a metagalactic supernova event, if we think of them as run-of-the-mill metagalactic systems with the same physics as galaxies or stars, then a metagalactic SN could be triggered by a metagalactic scale interaction.

Elinor said...

I just bought a light bulb with a longer life expectancy than mine. Why can't you ask questions that might change that?

Kimmo Rouvari said...

Dear Sabine,

If I give you the answer(s), with proofs of course, would you believe it? That's the real question, seriously.

Please, read this paper (ToEbi) and say do you believe it or not. But remember, my claims are verified already.

Vijay.Strings said...

Madam,

Adding a bit more here.
May be the mathematics we know could be the right one. The difference might be the way we do computations and the way nature does the computations.

Sabine Hossenfelder said...

Marko,

"the dynamics of human emotions is hopelessly beyond any mathematical description. Also, the qualia stuff, perception of the color red, etc."

How do you know? I don't see anything that prevents us, in principle, to describe human emotion in mathematical form. Not that this is presently possible though. And there's no such thing as 'qualia', I wish people would stop talking about this nonsense. Best,

B.

Sabine Hossenfelder said...

Kimmo,

Not sure what you mean with 'proof', because some of the questions call for evidence. Would I believe you? Depends on how convincing you are. Best,

B.

Sabine Hossenfelder said...

Elinor,

I'm a physicist, not a physician. Best,

B.

Kimmo Rouvari said...

@Sabine By proof I mean experiments which can't be explained or calculated by contemporary physics. Good examples are for example flyby anomaly and modified Cavendish experiment (link inside the paper).

My model predicts 1.111 mm/s anomalous speed increase at perigee for Juno (Results are not yet revealed). Naturally all known interactions can be calculated based on my model and its equations. And blah blah... but these for the start ;-)

Michael Gogins said...

Thanks for your questions. I'm not a scientist, but I used to try to write science fiction about the far future, and I love science, so these sorts of questions were in my mind then and still are now. The ones that concern me are the theory of everything, and the multiverse.

I don't have a definite conclusion, but here are the thoughts that keep circulating. There appears to be a real physical randomness that can be certified, to me this seems to mean that Nature is not computable. Does that also mean that Nature is not lawlike? Perhaps this is related to quesitons about Nature and mathematics. I'm aware that experiment and theory are dialectical, but as theories improve, the energy required to test them goes up, so progress would seem likely to slow down. Maybe there's a lawlike, true theory of everything but we will just never be able to figure it out because we will not be able to discriminate between the candidates.

As for the multiverse, the idea that Nature would be bounded would imply that it is computable, so I think that if randomness is real, then by contradiction Nature is not bounded in some fundamental sense, perhaps not only with respect to the time evolution of the future, but also in space and perhaps even with respect to what we think and decide.

When I think about Nature being bounded, even in a closed form, I just throw up.

Uncle Al said...

Cold fusion: Japan’s "New Hydrogen Energy” program invested US$20 million 1992 - 1997. Nothing. May 2008, respected academic Yoshiaki Arata said dispersed palladium on zirconia was the magic. Nothing. (But did they pursue surface plasmon resonances with Raman enhancement hot spots in metallic palladium nanoparticles?)

Magnetic motors: "The two most abundant elements in the universe are hydrogen and stupidity,"

http://www.youtube.com/watch?v=KBZTXdf7c-o
No wires.
http://www.youtube.com/watch?v=xbCN3EnYfWU
"I made a heart, a spiral, and a square"

Antigravity drives: Gravitation is elliptic space. Anti-gravity is hyperbolic space. Hey Zephir - learn to crochet spacetime,

http://www.amazon.com/Crocheting-Adventures-Hyperbolic-Planes-Taimina/dp/1568814526
200 full color photographs!

MarkusM said...
This comment has been removed by the author.
jal said...
This comment has been removed by the author.
jal said...

What if we were able to experimentally determine that a proton is dissipating energy and that it needed an input of energy to remain stable?

What if that effect of that inflow of energy was gravity?

Where would we look?

What would be the constrains?

Here is a paper to wet your appetite.

http://arxiv.org/abs/1202.5097

Matter Non-conservation in the Universe and Dynamical Dark Energy
Harald Fritzsch, Joan Sola
(Submitted on 23 Feb 2012 (v1), last revised 30 Aug 2012 (this version, v3))
In an expanding universe the vacuum energy density \rho_{\Lambda} is expected to be a dynamical quantity. In quantum field theory in curved space-time \rho_{\Lambda} should exhibit a slow evolution, determined by the expansion rate of the universe H. Recent measurements on the time variation of the fine structure constant and of the proton-electron mass ratio suggest that basic quantities of the Standard Model, such as the QCD scale parameter \Lambda_{QCD}, may not be conserved in the course of the cosmological evolution. The masses of the nucleons m_N and of the atomic nuclei would also be affected. Matter is not conserved in such a universe. These measurements can be interpreted as a leakage of matter into vacuum or vice versa. We point out that the amount of leakage necessary to explain the measured value of \dot{m}_N/m_N could be of the same order of magnitude as the observationally allowed value of \dot{\rho}_{\Lambda}/\rho_{\Lambda}, with a possible contribution from the dark matter particles. The dark energy in our universe could be the dynamical vacuum energy in interaction with ordinary baryonic matter as well as with dark matter.
===

John Merryman said...

I'll go with Doc G on the issue of time. It's the changing configuration of what is, that turns future into past. Each of us just happen to be one of those molecules bouncing around this thermodynamic state of being and so experience it as a sequence of encounters and psychologically treat it as a line from one to the next, which physics further reduces to measuring the process between encounters, as duration and relating this measure to relative measures of distance.
So while the physical laws governing the process do seem entirely deterministic, the lightcone of any event is only completed by the event, so there is no theoretical or practical way to know the input into the event. Which does complicated any basic form of determinism.

Phillip Helbig said...

"You are just a thought that someone
Somewhere somehow feels you should be here
And it's so for real to touch
To smell, to feel, to know where you are here"

Bonus points if you recognize the quotation without looking it up.

Don Foster said...

Thank you for the links, Markus. They were both to the point and, for the most part, accessible.

And a general thanks for some very interesting comments here.

Uncle Al said...

@jal
"a proton is dissipating energy" As what output? If nucleons are "losing mass" then optical (lepton) relationships in ultra-precision experiments will shift in the observation interval. They don't, e.g., arxiv:1303.2747, single atom atomic clocks, hydrogen hyperfine transition at 1420.405751766 MHz vs. reduced mass of the proton-electron orbit.

http://www.cv.nrao.edu/course/astr534/HILine.html
http://articles.adsabs.harvard.edu//full/1994ApJ...423..522G/0000522.000.html

Nucleon masses impact the Weak interaction (leptons). Type II supernova cloud brightness over time is positron-decay: Ni-56 to Co-56 to Fe-56. Decay curves would be anomalous vs. redshift, as would stellar evolution through fusion reactions and their interim decays.

My appetite remains unwhetted.

Unknown said...

The signal to noise ratio in the comments section is getting smaller and smaller, such a shame since the blog entries are really well written and interesting. Maybe it's time to filter out some noise?

jal said...

Thanks Uncle Al

I’ll read those links later.

You have increased the number of stones where the answers will not be found.

There are still a lot of stones to look under. The perpetual immortal proton must also have none changing variables of what makes up a proton. No inputs of energy and no dissipation of energy.
(quarks, gluons, higgs)

Sabine Hossenfelder said...

Marcus,

Thanks for the interesting references, will have a look at this. Best,

B.

Sabine Hossenfelder said...

Unknown,

Sorry, I haven't had time to look at the comments for a few days. Most of the comments here are actually on-topic though. The problem is that the display of comments on blogger and the absence of a comment rating feature makes the comment section rather unreadable if it gets long. But, eh, you see, for this reason it's a self-limiting problem ;p Best,

B.

William Wallace said...

Some of the posters recently becoming active in this comment section I've encountered elsewhere, such as on various google physics groups. Also on the open comment sections on Physics arXiv and similar free-access places. Always the same topics and style.

However, I never see them formally debate on physics.org forums nor, say, on any other proper debate and/or debunking sites. They seem to inhabit only those places where no or low moderation and certainly no formal peer review exist.

Not naming names, but you may need to institute some blocking features before you are overwhelmed. This is far too interesting a blog to let it get invaded by the far-out physics groupies.

(Meant as private message, but no big deal if this goes through.)

Don Foster said...

First, my questions:

1) What was the first distinction, the universe’s most primordial “bit”?

2) Are the “laws of physics” emergent or given.

3) What is the natural physical origin of “re-” (the prefix i.e. reflect, return)?

4) Is energy emergent?

5) Does energy have an integral and inherent counterpoise?

My answers, should you need them:

3) Is mathematics the best way to model nature?
Yes, within the bounds of science, though, as a practical matter, no. We manage to move within an exceedingly complex dynamic without frequent recourse to mathematics (the image here is that of an outfielder who runs to place her glove directly beneath the descending high fly ball).

4) Does a theory of everything exist and can it be used, in practice (!), to derive the laws of nature for all emergent quantities?
If we accept this implausible universe as a given and ourselves as integral to it, then, judging by past performance, science will continue to lengthen its leverage.

The name “theory of everything” is playfully hyperbolical. Science need not fear obsolescence due to lack of things unknown.

1) Is the time-evolution of the universe deterministic, indeterministic or neither?
“Both” would be the answer with the most consequence. Perhaps, in its brief private time before science lifted its veil, the nascent universe was busy calculating. It followed every path, probed every possibility and determined a set of physical laws that would produce a universe with a high Kolmogorov complexity. So, upon some axis the universe exists in crystalline fixity, while simultaneously upon another, we are plodding through the calculation.

DocG said...

I think that at the root of all these problems is the problem posed by science itself. Science both is and is not a kind of window onto reality. It is in the sense that it is science which posits the difference between reality and unreality in the first place. So only science can make that distinction.

But it isn't in the sense that it is not only a window but also a kind of game, with implicit rules that are too often taken for granted. Such as:

1. You need to have a clear distinction between a subject and an object.

2. You need certain rules of thumb that can never be proven, such as Occam's Razor.

3. You need the sort of problems that can be treated mathematically.

4. Etc.

The subject object distinction is particularly problematic when it comes to quantum theory, in which that distinction apparently breaks down. And when that happens then the distinction between what is real and what is unreal also breaks down. Which means there is a danger of science simply becoming a kind of game, almost in the sense of Hesse's Glass Bead Game.

Hal Swyers said...

Apologies in advance, I just have a slightly different opinion and list of questions

http://thefurloff.com/2013/11/25/things-that-keep-people-up-at-night/

Sabine Hossenfelder said...

William,

I only pre-screen comments on posts older than 2 weeks. (Comments on older posts are almost always spam.) If you want to send me a private message, please send an email. I see your point regarding repetitive comments. Alas, this blogpost explicitly invited contributions in the comments, so is fine by my. Best,

B.

John Merryman said...

Doc G,
Another aspect of that is that information is inherently subjective. Much like taking a picture requires focusing, aperture and speed settings, direction/point of interest, etc. Otherwise the information is blurred and too much just becomes 'white noise.' It is inherent in the relationship between the observer and the observed. Scaling in either direction means losing information. Either loss of detail in the broad view, or loss of context in focus on detail.

Don Foster said...

@John

“….information is inherently subjective.”

In focusing on your phrase here we may lose the broader meaning of your comment, granted. The issue is whether “information” is more than an artifact of human cognition or whether it is better understood as an integral and active agency in actual physical dynamics apart from any observer.

Unlike the Eskimo and his snow, we lack the words to discriminate between various meanings of the word information, subjective or objective.

No doubt there are better explanations, but here’s a simple-minded analogy. We are given a field newly planted in corn and beside it a ditch carrying water recently descended. The farmer places a rock in the ditch to divert a portion of the water into his field. Here the rock may be understood as the business end of “bit” and, more interestingly, the budding end of boundary.

Zephir said...

/*...I never see them formally debate on physics.org forums nor, say, on any other proper debate and/or debunking sites. They seem to inhabit only those places where no or low moderation and certainly no formal peer review exist..*/

This is solely relative stance, as some even more formally and less philosophically thinking physicists arguably and repeatedly consider Bee as the same troll, as you're considering these "crackpots". The mainstream physic community can punish its heretics and renegades quite hardly. Frankly, I'd send all censors to countries, where they belong, i.e. into Cuba or North Korea, where they can apply their infallible talent for distinguishing, what is correct in science and what it's not.

andrew said...

Is the time-evolution of the universe deterministic, indeterministic or neither?

I used to care a lot about this one. The older I get, the less I care. In part, the discovery of chaotic but deterministic dynamics and an understanding of how structured "random" in the quantum mechanical sense is has made it less salient. The line between deterministic and stochastic is thinner than it seems.

Does a younger version of yourself still exist, just that you’re not able to communicate with him (her), or is there something special about the present moment?

This segue from the first question into this second one, in contrast, grows more interesting. QCD is not obviously deterministic in one time direction and stochastic in the other. Indeed, the equations don't work that way when you calculate with them. GR moreover debases the notion that there is any one "present" moment that is consistently true for all observers. Hence, one may need to talk not just about the existence of present v. past and future, but of present to you at various points in universe v. someone else's present at those same points in the universe. The present may exist, but be both empheral and strictly local, while the past, the future, and the non-local present may be indeterminate.

Is mathematics the best way to model nature? Are there systems that cannot be described by mathematics?

Consider the non-mathematically described part of nature. Can it not be described by mathematics because it is indescribable, or because it can be described but not by not by mathematics. If so, what distinguishes non-mathematics from mathematics in that context. Given the incompleteness theorem, it is not implausibly that some of the universe can't be described by mathematics, but without examples of what that would look like it is hard to imagine.

Does a theory of everything exist and can it be used, in practice (!), to derive the laws of nature for all emergent quantities?

I think that the answer is yes, but that science will merely slow rather than come to an end as it acquires diminishing marginal utility. Also, some areas of science will stagnate more quickly than others. You can put a man on Mars with 17th century mathematics, but it takes 20th century materials science.

John Merryman said...

Don,
You are right the word information has different contexts. In that context it would be as knowledge.
The physical information you describe would be what defines the energy that manifests the information. Since the energy is dynamic and therefore changing form(information), the arrow of time for the energy is past(configurations) to future(ones). While the arrow of time for the information is from future(potential) to past(residual).

John Merryman said...

Even as a boundary though, it is subjective, not absolute. Send a lot of water down that ditch and it will wash away. The bit becomes zero, not one.

Don Foster said...

Actually, that does not seem to be the case. Subjective means – “dependent on the mind or on an individual's perception for its existence.” We’re on the verge of a philosophical rabbit hole, but I don’t believe the rock is in need of my acknowledgement.

Information is a preserved quantity in physical interactions. Physicists went through a lot of grief because black holes seemed to be gobbling the stuff up. Check out the black hole information paradox.

John Merryman said...

Don,
I have to admit to being somewhat skeptical of the direction physics has gone, ie. a crank.
Black holes are a vortex. For example: http://phys.org/news/2013-09-black-holes-ocean.html#jCp
"According to researchers from ETH Zurich and the University of Miami, some of the largest ocean eddies on Earth are mathematically equivalent to the mysterious black holes of space. These eddies are so tightly shielded by circular water paths that nothing caught up in them escapes."
Vortices eject their contents out the poles and galaxies have enormous jets of energy shooting out their poles. As I see it, the energy isn't lost, but any information previously carried by it is.
As I described above, I see time, ie. changing configuration, as an effect of action, similar to temperature. Not as some elemental dimension of reality. Relativity is based on the speed of light, yet this dynamic quality of light seems left on the cutting room floor, in order to make the static geometry somehow foundational. Physics seems a little too hung up on its static models and neglects the dynamics actually giving rise to them, so it likes to think information is indestructible.
It seems to me that conservation of energy would mitigate against the conservation of information, since creating new information requires erasing whatever message was previously recorded on the required medium.
Just because it is difficult to ascribe simultaneity to different events, doesn't make those events somehow more real than the processes causing them.

Andrew said...

I much preferred your initial thoughts, like "Should I resend this email?" :)

Andrew said...

Is free will an illusion? I thought all physicists already agreed with you on that.

Don Foster said...

Andrew,

“The line between deterministic and stochastic is thinner than it seems.”

Surely we have a choice in time-evolution process beyond deterministic and Brownian motion.

Robert L. Oldershaw said...

Another question that should keep us awake at night is: How do we reconcile QM and GR.

Towards that end, consider the following *empirical* evidence.

I found a very good catalog of detached eclipsing binary stars with mass determinations "accurate to 2%". It is an ongoing catalog with new systems being added as they are published.

http://www.astro.keele.ac.uk/jkt/debcat/ [John Southworth's DEcB Cat]

This would appear to offer a good preliminary sample with which to test my hypothesis that the total masses of binary star systems (and single white dwarfs) have distributions that are characterized by preferred masses that are integer multiples of 0.145 solar mass.

Taking only 2012 and 2013 data from Southworth's catalog (I am only interested in new mass determinations), I find a sample of 36 systems with sufficiently narrow error bars for an adequate preliminary test of the hypothesis.

Of the 36 test systems, 77% are located at <0.04 solar mass from one of the predicted preferred masses. Roughly 22% are located at =/> 0.04 solar mass.

The total masses for the EcB systems cluster around the predicted masses. A histogram of the + and - deviations is centrally peaked at the generic multiple value.

These results seem much better than the results for the small sample of neutron star binary systems, with the previously noted heterogeneity in error estimates.

I am of course wondering if I have something to write home about yet, and I am hoping that the readers will have some constructive criticism.

Perhaps I might also get some advice on the best way to analyze the data so as to clearly demonstrate what the data say, and what they do not say.

If stellar systems have quantized masses, and bear in mind that we cannot cool stars to very low temps, isolate them, shield them from external fields, etc., then the physics of the microcosm and macrocosm might be far more unified than previous superficial comparisons have suggested.

This might not solve the GR-QM incompatibility, but it would chart a new path to doing so.