Decoherence and the randomness of collapse

[Gunner B]

it is completely acceptable to adopt complete agnosticism, and indeed it is far more important for the scientist to practice skepticism than it is to embrace faith.

I agree that it's acceptable and that it's far more important to practice skepticism but*I don't think it's good to say "I don't think we can explain what is actually happening because it looks complicated. So, if you try to explain what is actually happening I'm going to think it's wrong, even though I don't have a better explanation."*
That's what Newton said about the ontology of gravity and I'm glad Einstein was able to, somewhat, prove him wrong with GR (gravitational effects come from the warping of space-time from mass/energy).
Unfortunately, it seems as though Einstein's approximations don't withstand in all of the circumstances of the universe, just like Newton's didn't.

But, it seems like what you're saying is we've reached a point in time where physics and metaphysics cross paths and to the untrained eye one might confuse metaphysical claims with actual science. I'm saying that, I think, *I do a good job of distinguishing those claims when making a choice of what to believe as truth, falsity and probable. This, to me, is the essence of skepticism. I think the probable part is important though, because I believe that for a claim or theory to be probable it must be based or influenced on scientific facts (other claims proven by experiment) and explain a certain phenomena accurately.*

The role of expectation is quite simple: we benefit from expecting the same things to happen in the same circumstances, and a principle of physics is simply an inductive grouping of all the noticed similarities. *

"Inductive reasoning allows for the possibility that the conclusion is false, even where all of the premises are true." (John Vickers. The Problem of Induction. The Stanford Encyclopedia of Philosophy.)
*
So, according to you, String Theory is a principle of physics. String Theory, from what I know (prove me wrong), is nothing more than a way of explaining something through an "inductive grouping of all the noticed similarities". To go father than similarities, I would like to know how String Theory isn't mostly based or influenced by scientific facts (proven by experiment).

*
When the group is expanded to include fundamentally new members, the principles usually require modification in some surprising way. That has been the history of physics from the start, what I don't get is why so many people seem to expect it to work differently this time.

General Relativity + Standard Model = Surprising new way to really explain
black holes and the big bang. (see below)

"Black holes draw audiences, because they are weird, they are profound, they are Albert Einstein and Steven Hawking rolled into a singularity. Or some such – except, none of this is actually the case. The black hole is a much more mundane concept, older than relativity, and despite much misinformation in popular and pseudo science, black holes have in a certain sense little to do with relativity (and I say this although and because I worked for many years on black holes and used general relativity when doing so).

*...Let us get one issue out of the way right now, before even discussing escape velocity, which I will introduce below: A black hole is a body so massive that its escape velocity v exceeds the speed of light c.
*
That’s it – no more – that’s what it was in 1783 already, and this is what it is still today, and relativity did not change a thing about it! Yes, you read correctly: this is still today the only and proper definition of a black hole. Read it again, learn it once and for all, and remember that it does not involve anything weird, like singularities or pathways to other universes, at all. Moreover, black holes are by now well known astronomical objects – they are out there and we have observational evidence...[W]hat did relativity add? Relativity added two issues: Firstly, special relativity found out that nothing can go faster than light. Only in this sense does the “hole” aspect of the black hole become established by relativity. However, dear Wikipedia writer, NOT BY GENERAL RELATIVITY! The fact that light velocity is the limit is mere special relativity!
*
What general relativity added is basically only confusion: If general relativity holds true inside the black hole, there could be, in some cases should be a singularity inside. This however is no more than a sign; a little red flag indicating that general relativity is probably not true far inside a black hole. A singularity is here related to an infinite (divergent) density. This is not weird, not philosophy, not time travel or warp drive, not worm hole or quantum healing, dear Hawking and Caroll and so on, although such silly interpretations do sell silly books. A divergence to infinity in a physical theory is no more than a sign that the theory has left its domain of applicability and should be replaced by something better in the future.
*
Why do I ride on this singularity issue? I like to teach science properly, like in the boring universe,
so that people learn something and do not just go home with their heads full of misleading rubbish plus the notion that I am awesome. People who are under the misconception that black holes involve singularities are also under the impression that black holes have not been found in astrophysics, and that is just wrong. It is well established *that there are black holes in every spiral and elliptical galaxy. The best observational evidence derives from our own galaxy, the Milky Way.
*
So, the next time somebody rambles on about that he or she knows all about the mysterious physics of black holes, the answer is not “Ohhhhhha! Wow!”, but “Do you even know what a black hole is at all?” "
*
In replies that aim to discount what he said about GR and SR, he adds the comment: "I also like to stay close to what experimental observation actually tells us. It tells us that black holes exist all over the universe, but your big name singularities however only exist on paper."
and "infinite density is nonsense. Newton knew that, Einstein knew that (that's why he initially put in the cosmological constant - he only later changed his mind, due to Hubble's discovery), and we nowadays also know that, since there is no infinite density at the start of the universe (there is inflation before the big bang)."*
and, finally, rhetorically adds "So why then does String Theory work without Singularities?"
(It's probably better if you read the entire blog post + comments, if you are interested:*http://www.science20.com/alpha_meme/black_holes_demystified-71881)

Other problems:*
"In the case of a charged (Reissner–Nordström) or rotating (Kerr) black hole it is possible to avoid the singularity. Extending these solutions as far as possible reveals the hypothetical possibility of exiting the black hole into a different spacetime with the black hole acting as a wormhole. The possibility of traveling to another universe is however only theoretical, since any perturbation will destroy this possibility. It also appears to be possible to follow closed timelike curves (going back to one's own past) around the Kerr singularity, which lead to problems with causality like the grandfather paradox. It is expected that none of these peculiar effects would survive in a proper quantum mechanical treatment of rotating and charged black holes.

The appearance of singularities in general relativity is commonly perceived as signaling the breakdown of the theory. This breakdown, however, is expected; it occurs in a situation where quantum mechanical effects should describe these actions due to the extremely high density and therefore particle interactions. To date it has not been possible to combine quantum and gravitational effects into a single theory. It is generally expected that a theory of quantum gravity will feature black holes without singularities.

...Although general relativity can be used to perform a semi-classical calculation of black hole entropy, this situation is theoretically unsatisfying. In statistical mechanics, entropy is understood as counting the number of microscopic configurations of a system that have the same macroscopic qualities (such as mass, charge, pressure, etc.). Without a satisfactory theory of quantum gravity, one cannot perform such a computation for black holes. Some progress has been made in various approaches to quantum gravity. In 1995, Andrew Strominger and Cumrun Vafa showed that counting the microstates of a specific supersymmetric black hole in string theory reproduced the Bekenstein–Hawking entropy. Since then, similar results have been reported for different black holes both in string theory and in other approaches to quantum gravity like loop quantum gravity." (http://en.m.wikipedia.org/wiki/Black_hole)


This is where I compare String theory and all other unifying, yet to be unifying and un-unifying theories to the marvelous example of the geocentric model vs. the heliocentric model.

A long time ago a very smart man named Ptolemy created a beautiful, though complicated, mathematical theory describing a model of our solar system in which the sun and all other planets revolved around the earth. His theory explained something that almost everyone expected at that time to be true.

“The astronomical predictions of Ptolemy's geocentric model were used to prepare astrological charts for over 1500 years. The geocentric model held sway into the early modern age, but was gradually replaced from the late 16th century onward by the heliocentric model of Copernicus, and Kepler.”

It took 1500 years to come up with a mathematically different theory!
After Copernicus’s new theory of heliocentrism, it then took an additional 200 years to officially prove his theory, and thereby disprove the geocentric model, with the observational evidence of William Herschel, using the newly invented telescope.

The moral of the story is that String Theory explains something, that our current theories do not, and does so without experimental evidence. Although it seems like there is no experimental evidence for singularities? So, in that case, String Theory does a much better job of explaining the mechanisms of physical reality than just General Relativity alone. Anyhow, String Theory could be, and probably is, a geocentric model. We won't know until we can test it. We probably can't test it until we come up with something as revolutionary as the telescope. If it is, I congratulate the founders for explaining something (wrongly) and for influencing research to find the truth; just as I would for the intelligent man who created the geocentric model and just as the geocentric model probably did.

P.S. I saw that you mentioned "cosmic censorship", is this a philosophical argument?

It seems as though Hawking lost a bet on it. Doesn't mean it isn't credible though... Just wondering.

 

[Ken G]

I don't think it's good to say "I don't think we can explain what is actually happening because it looks complicated. So, if you try to explain what is actually happening I'm going to think it's wrong, even though I don't have a better explanation."

But I would never say that, because I have a more defensible view of the meaning of the term "explain" than what is normally used. The defensible meaning of "explain" is merely "forming language that gives us both a sense of understanding and useful predictive power". That's it, that's all "explain" ever means-- it certainly nevers means "find the truth behind" or "discover an irreducible description of", even though you'd think it did mean that the way some people use the term. So Newton explained Kepler's laws with a theory of gravity that wasn't correct. We still use that incorrect theory to explain Kepler's laws, and indeed they still do explain them! Explaining something, and being right, are very different animals, so I think we explain all kinds of complicated things, and I don't think we are right, I think we are doing physics.

I'm saying that, I think, *I do a good job of distinguishing those claims when making a choice of what to believe as truth, falsity and probable.

But what is this claim really saying? Would not Aristotle have said that? Newton? Einstein before quantum mechanics? What does it mean to "do a good job"? Yes, we do a very good job of explaining many things, but we should not then conclude that we are "probably" correct, in fact we are probably quite wrong, and a thousand years someone will look at us as quite naive to have imagined that we were probably right about almost everything that we now imagine we are probably right about.

String Theory, from what I know (prove me wrong), is nothing more than a way of explaining something through an "inductive grouping of all the noticed similarities". To go father than similarities, I would like to know how String Theory isn't mostly based or influenced by scientific facts (proven by experiment).

String theory is not really an inductive grouping of phenomena at all-- the grouping of phenomena was done by quantum mechanics and general relativity, in two different groups. String theory tries to unite them in a single group, but there is nothing about the phenomena themselves that are similar, the unification is a kind of shotgun wedding. Granted, it is valuable to unify if possible, but nothing about string theory comes from observations. The number of observers working on string theory are few or none, whereas most areas of physics have observers outnumbering the theorists.

The moral of the story is that String Theory explains something, that our current theories do not, and does so without experimental evidence.

But it isn't clear to me what string theory is supposed to explain. The examples I see from that blog are the entropy of a black hole, but the blog also says that loop quantum gravity can do that too! So apparently it's not that hard to do. Or, it might be that string theory explains the absence of singularities, but the blog also mentions that Kerr black holes don't have singularities either, and of course all black holes will be Kerr black holes! So I just don't see what string theory is explaining here. The analogy with the heliocentric model isn't all that clear either, because the blogger appears to associate string theory more with the geocentric model anyway-- basically what you get when you form a highly rationalistic theory without close observatonal constraints. Even if one thinks that string theory is like heliocentrism, there still was no way for physics to tell which model was better until the observations got better. So the one thing I can agree with from that blog is that the real value of any of these modes of thought is not if they are likely to be true or not, but simply how they might help us figure out what observations we need to do to tell. That's what science is really all about, not guessing what is probable vs. "bizarre." (I'm not objecting to the blog, I think it raises some good talking points, I just don't really agree.)

P.S. I saw that you mentioned "cosmic censorship", is this a philosophical argument?

It is true that the phrase comes up a lot when discussing "naked singularities", which GR appears to allow but which causes most physicists distress to imagine. But I just mean it in the more general sense of any seemingly unphysical behavior that some theory allows, and how the universe must find some way to avoid having it actually happen, without the theory actually being wrong. So the list includes closed timelike loops, the "many worlds" of unitary quantum mechanics, FTL communication via entanglements, etc.

 

[Gunner B]

But I would never say that, because I have a more defensible view of the meaning of the term "explain" than what is normally used. The defensible meaning of "explain" is merely "forming language that gives us both a sense of understanding and useful predictive power". That's it, that's all "explain" ever means-- it certainly nevers means "find the truth behind" or "discover an irreducible description of", even though you'd think it did mean that the way some people use the term. So Newton explained Kepler's laws with a theory of gravity that wasn't correct. We still use that incorrect theory to explain Kepler's laws, and indeed they still do explain them! Explaining something, and being right, are very different animals, so I think we explain all kinds of complicated things, and I don't think we are right, I think we are doing physics.

I completely agree that 'to explain' means "forming language that gives us both a sense of understanding and useful predictive power". But, isn't it personal preference if you desire to find the ultimate understanding behind something (or everything) and by understanding it you also get useful predictive power? You say "it certainly never means "find the truth behind" or "discover an irreducible description of", even though you'd think it did mean that the way some people use the term."

I don't want to spend my life working on physics mainly so people can use it for "practical" use. If I wanted to do that I would become an engineer. Mind you, I don't think engineering is a waste of time at all but I think that in the pursuit of understanding, wisdom and the ontology of science you get the new physics that becomes the foundation of engineering. This is the main reason why I prefer theoretical physics over experimental. Although the more I learn, the more I feel like if I were to pursue a career in theoretical physics that I will be seen as a philosopher of metaphysics and not a physicist or scientist. That worries me. Perhaps I can become both a theoretical and experimental physicist. I don't know, but all I do know is that I want to find truth. Is this a bad thing? Or a wrong way of looking at physics and science in general?

For example, In the late 17th century, when Isaac Newton discovered the first force of nature - gravity, he was able to create a whole new field of mechanics that gave rise to the industrial revolution. This new age lifted human society from its primitive ways and relieved countless numbers of people from pain staking poverty through the development of large scale farming. Not soon after, discoveries made by Michael Faraday, James C. Maxwell and Nikola Tesla led to our understanding of the second force – electromagnetism, that made possible the invention and operation of every electrical device ever made including television, radio, radar, computers and the Internet. Finally, when Albert Einstein discovered that mass could be turned into energy and vice versa, through his famous equation E = mc2, it helped unlock secrets of the final two forces – the strong and weak nuclear forces; thereby allowing us to harness the profound energy of nuclear power and understand the violent processes of the stars in the heavens.

I might be misinterpreting what I've read about these scientists, and Einstein specifically, but I thought they were motivated by the understanding of the universe, which lead them to make these discoveries and then people discovered the practical use and "predictive power" behind them.

I'm not sure if what you meant by "predictive power" was 'in order to predict how an event will evolve according to the laws of physics (like the big bang and black holes)' or if you meant 'in order to predict when the sun will rise everyday of the year so I know when to plant crops and so we can build steam engines and a Global Positing System with special relativity'. I kind of interpreted it the second way because of the contrast with the word "understanding" in the ontological sense.

If this is just your personal opinion then I suppose we should just agree to disagree but if my thinking is somehow universally wrong I would like to know.

String theory is not really an inductive grouping of phenomena at all-- the grouping of phenomena was done by quantum mechanics and general relativity, in two different groups. String theory tries to unite them in a single group, but there is nothing about the phenomena themselves that are similar, the unification is a kind of shotgun wedding. Granted, it is valuable to unify if possible, but nothing about string theory comes from observations. The number of observers working on string theory are few or none, whereas most areas of physics have observers outnumbering the theorists.

You may be completely correct, but I have no way of knowing, so in that way I suppose it's my fault for posting about something I have such an unclear understanding of. Do you dislike it when people post about physics while having almost no understanding of the math behind it?

It is true that the phrase comes up a lot when discussing "naked singularities", which GR appears to allow but which causes most physicists distress to imagine. But I just mean it in the more general sense of any seemingly unphysical behavior that some theory allows, and how the universe must find some way to avoid having it actually happen, without the theory actually being wrong. So the list includes closed timelike loops, the "many worlds" of unitary quantum mechanics, FTL communication via entanglements, etc.

I don't think you mean this in an anthropomorphic way, so does this mean the theory has a good chance of being wrong in explaining (the understanding part) while being correct in explaining (the "predictive power" part)? It would seem like to me, if a theory isn't correct in explaining all phenomena that is observed it is isn't completely, universally, correct. For example, I agree that "Newton explained Kepler's laws with a theory of gravity that wasn't correct. We still use that incorrect theory to explain Kepler's laws, and indeed they still do explain them!" but his theory only explains things like going to the moon or an OK approx. of the motion of the planets (GR is much better), etc..
If that's all you think that physics should do then that is your opinion; it certainly isn't mine.
Or do you mean that the problems of "closed timelike loops, the "many worlds" of unitary quantum mechanics, FTL communication via entanglements, etc." are physically impossible or physically impossible to observe? In which case the theories are never (universally) wrong. (seems unlikely)

 

[Ken G]

I think you might be misunderstanding me. What I have said is not opinion, it is just the facts about what physics has always been. Physics has always been a search for effective truth, not for actual truth. Physics has no idea what an actual truth even looks like, but it knows a lot about what an effective truth is-- it's history is rife with them. So you needn't worry that a theoretical physicist is doing metaphysics unless they imagine they are seeking absolute or ultimate truth. If they recognize what they are actually doing, seeking usable, meaningful, approximate, idealized, effective truths, just like their forbears were doing, then they can be completely confident that what they are doing is physics, not metaphysics. Newton's revolution in physics is a perfect example-- he changed the course of physics, yet not a single one of the theories he introduced is correct. Does this make him a failure? No. Does this mean he didn't understand gravity or motion? No, he understood them very well-- but we wasn't right about them. See the difference?

 

[Gunner B]

Sorry, I was incredibly unclear of what I meant by "ultimate truth". I define it as a view that links the mechanisms of objectivity to the mechanisms of subjectivity in the most approximate (possible) harmony. (I hope this definition is clear enough for you to understand my thinking haha but I think it matches what you are saying about effective truth.) These views can only be approximate because they are obscured by our subjective experience (wavelength of light reacts with chemicals in our brain that give us a way to differentiate things in our environment) and this is the same with physics and the universe. In that way we can never have an absolute truth but we can understand something very well and have better approximations. I understand, but I don't think it's good to assume how limited the approximations can or will be. Imagine explaining quantum physics to Socrates or Newton even.

After all, we are a mechanism of the universe. I think this quote from Einstein sums it up: "A human being is part of a whole, called by us the Universe, a part limited in time and space. He experiences himself, his thoughts and feelings, as something separated from the rest - a kind of optical delusion of his consciousness. This delusion is a kind of prison for us..."

Perhaps we will evolve in a way that subjective experience and understanding will be a limit approaching the objective absolute truth, without ever reaching it completely.

 

[Ken G]

These views can only be approximate because they are obscured by our subjective experience (wavelength of light reacts with chemicals in our brain that give us a way to differentiate things in our environment) and this is the same with physics and the universe. In that way we can never have an absolute truth but we can understand something very well and have better approximations. I understand, but I don't think it's good to assume how limited the approximations can or will be. Imagine explaining quantum physics to Socrates or Newton even.

Yes, that's the point-- what Socrates and Newton viewed as "understanding" was quite different, it was the understanding they were ready for. So it is for us today, we seek the understanding we are ready for. That's very much what I mean by "effective truths." So it is a quest for understanding, certainly, but the understanding we achieve is provisional, approximate, idealized, and useful to us, but not "true." And that's OK, it is supposed to be like that-- we only run into trouble when we imagine that our current understanding is the "ultimate" one, or that the "theory of everything" is just around the corner. What generally happens, instead, is that each new insight opens even more profound mysteries than the ones we had before. The way I like to say that is, science is not about demystification, it is about replacing superficial mysteries with much more profound ones. This is physics, not metaphysics, as long as there is still mystery.

I think this quote from Einstein sums it up: "A human being is part of a whole, called by us the Universe, a part limited in time and space. He experiences himself, his thoughts and feelings, as something separated from the rest - a kind of optical delusion of his consciousness. This delusion is a kind of prison for us..."

Yes, that "prison" is very much what most of my above posts were about as well. But we shouldn't view it as a bug of science, it is a feature-- we can do experiments from the safety of our prison cell, and generate understanding of what is outside (a metaphor I do not mean literally), without needing to pretend that we discover what is outside. What is outside is itself just a useful metaphor.

Perhaps we will evolve in a way that subjective experience and understanding will be a limit approaching the objective absolute truth, without ever reaching it completely.

My point is that there is no such thing as the "objective absolute truth"-- there is the scientific truth, and the metaphysical truth, and other types of truth. The scientific truth is never absolute, and is not even supposed to be. Some people are disappointed by this demonstrable fact about science, but I'd say that's the fun of science right there-- it's not a bunch of stodgy books, it is vibrant and alive and always on the move.