Battlefield 3 Unlocks the Secrets of the Universe

[Umbran]

There is a fundamental issue we face in this discussion.

It is not sufficient to say, "Hey, if I bend and flex this analogy a bit, it seems a bit like the real world!" So, cool! This is not a useful test of your theory. There is no point in considering a new model for the universe, unless it changes something. Finding another model that is also consistent is merely evidence that the two models are somehow equivalent, which is usually not very interesting. Kind of like saying, "Hey, 2+2 = 4, and 2 * 2 = 4! Isn't it cool that my multiplication gets the same result as your addition!!" What we then have is merely a cherry-picked instance where they happen to be the same thing, not the discovery of a major underlying principle.

In the process of science, if we have a model of the universe, and we want to see if it is true, we have to find something that model predicts that other models do not, and we test for that. This is a problem with what is commonly called, "string theory" the more popular class of possible solutions for marrying gravity and quantum mechanics in high energy physics and cosmology. String theories have an issue in that they haven't to date given us any testable results.

If you want to look at the host/client universe, you have to find something that it predicts that current theories *don't* predict, and test that.

One obvious one is, as I've noted, the update of universe state *after* it has been observed. If you can find instances of that update, you might have something. I think the existence of a "host" as final arbiter of reality would have other effects if you tried to include it in a mathematical model (instead of a merely descriptive analogy) would also yield testable results.

 

[tomBitonti]

I'm sorry, but that's not quite correct.

With a latency issue, there are two people *who disagree* about the state of the universe. What I observe and what you observe is different, and then gets overwritten with an update later. In latency, the universe gets rewritten every once in a while to make our views consistent.

That doesn't happen with entangled particles. In that case, at one point we *agree* that the particles are unobserved, or we *agree* what the states of them are. There is never a time when we disagree on what is going on in the universe. This is an important distinction - we cannot compare the latency situation in which we have both seen events, and they don't match, with the QM situation where neither of us have yet seen events, and the state of the system is not known to either of us. They are not equivalent situations.

Certainly. My point was that entangled particles don't have the latency problem: Their state resolution is coupled even though the resolution seems to occur with one particle at a distance from the other particle. ("Seems" with a very loose meaning; my intuition is that any misgivings about this way of describing what is happening are due to an incomplete understanding and due to a failure of everyday language rather than due to the phenomenon itself.)

That is, if the the initial question doesn't match what happens in quantum mechanics, are there circumstances where a similar problem is presented, and then, what happens under quantum mechanics? Can the client latency problem help us to understand quantum mechanics?

But, my correspondence isn't as exact as I was thinking when I wrote my most previous response. Two clients can't use entanglement to solve their latency problem, so the issue isn't exactly the same. I can imagine, in effect, communicating the result of a random process at a pre-specified point in the future, but that is quite different than communicating a definite state.

Thx!

TomB

 

[freyar]

I'll start by mentioning that I agree with Umbran's answers to your questions, but I'll throw in my 2 cents as well.

Well gang, I'll grant that 1) the laws of quantum mechanics and general relativity work really well, and that 2) you have much better understandings of these laws than I do. But I believe that the great unifiers are still battling it out, to see how the two laws (theories?) come together. And since I haven't heard explanations lately for where all the universe's dark matter is hiding, or why the universe's expansion is accelerating, I hope that we can agree that there are still some flaws in the maths.

There are a couple of levels of scientific theory here, and I think it's important to clarify in this case. What we call the "theory of relativity" (whether you're talking about special relativity or general relativity) and "quantum mechanics" are basically mathematical frameworks that underlie more specific theories. So, when I go teach quantum mechanics, I am teaching a set of axioms and mathematical tools and how they are used in specific theories. For example, the framework quantum mechanics is used in, for example, the BCS theory of superconductivity or models of atomic & molecular physics or beyond. Similarly, the basic framework of general relativity can be used in Einstein's general relativity but also carries over to many slightly modified formulations of gravity. We tend to use the word "law" (as in "law of physics") for a specific concept or rule in physics --- basically one equation at a time. "Law" tends to be used for the important ones; another similar word used in some cases is "theorem."

Regarding dark matter and dark energy, no, we don't know specifically what they are, but that's mostly a matter of specific theories. For example, a majority of physicists who've looked at the evidence are quite sure that dark matter is a new type of fundamental particle, described within the framework of quantum mechanics and more specifically particle physics (quantum field theory). The specific theory of those dark matter particles is unknown. Dark energy is a little more interesting, in that we may only understand it when we understand a complete theory of quantum gravity (which we don't quite have a framework for at the moment). But my feeling is that we likely understand what dark energy is (vacuum energy) but don't necessarily have a good handle on how to understand its value (though that's just a gut feeling).

I'll ask about relativity first:

[MENTION=40227]freyar[/MENTION]: how can every observer agree on what physical events happen, but not when they happen? The "when" seems pretty important to me, unless "when" is only a number on a clock. If you were in the open at 12:01 but behind cover at 12:02, then I hope I shot you at 12:01.

As Umbran mentioned above, events that can communicate with each other always stay in the same order. So, since I can tell myself "ow, I've been shot in the leg," those two events stay in order. Here's how I teach this in class: If two events happen at the same place relative to some person, they have a past-future ordering. So, relative to me, getting shot and getting behind cover happen at the same place--- at me. So they have order.

[MENTION=177]Umbran[/MENTION]: see the above case. If we can disagree on when getting shot occurred in relation to other events, and if another event is the arrival of a tank between you and me, then that tank might mean the difference between life and death.

We should be precise for this case. From my point of view, I'm at point A, and you're at point C shooting at me with a laser gun. A tank is driving through and passes point B, which is on a direct line between you and me. Now, if the tank and the laser pulse are both at point B simultaneously, everyone can agree I am not shot. If they're not, there is a clock sitting at point B that can tell me if the laser pulse or the tank is at point B earlier. BUT, the event of myself getting hit by the laser is somewhere else. Someone flying around in a relativistic rocket ship might see the tank pass point B before or after I get shot depending on the precise circumstances. And this all falls out of the math.

Also, shooter games do a certain degree of smoothing, so that updates to your game world don't look (too) awkward. If the universe runs on something similar to the Frostbite game engine, then there wouldn't be any obvious "please update" moments. Just tiny inconsistencies, like a single photon causing an interference pattern with itself.

I'll agree with Umbran's points about this and also say that you really have to be careful about saying things like "a single photon causing an interference pattern with itself." If you measure the position of a single photon --- for example, send a single photon through a device and see where it hits a screen --- you will always get a single position. The interference pattern shows up in the distribution of those positions if you repeat that single photon experiment many times. Yes, each photon is interfering with itself, but a single measurement doesn't see the whole pattern.

 

[freyar]

Here's a thing: The problem that you describe, of latency between clients, is exactly what is spookily solved by entanglement. Two particles are emitted, with balancing properties. One heads to the left, the other to the right. You might expect that the selection of which particle went in which direction to be set at the point of emission, but, it works out that decision isn't made until one of the particles is observed.

The strangeness is that because the particles have opposite properties, this fixes both particles. This happens no matter how far apart the particles are, and with no propagation delay. Physics avoids a problem which seems to be the same problem you describe between clients.

TomB

I'm sorry, but that's not quite correct.

With a latency issue, there are two people *who disagree* about the state of the universe. What I observe and what you observe is different, and then gets overwritten with an update later. In latency, the universe gets rewritten every once in a while to make our views consistent.

That doesn't happen with entangled particles. In that case, at one point we *agree* that the particles are unobserved, or we *agree* what the states of them are. There is never a time when we disagree on what is going on in the universe. This is an important distinction - we cannot compare the latency situation in which we have both seen events, and they don't match, with the QM situation where neither of us have yet seen events, and the state of the system is not known to either of us. They are not equivalent situations.

To add to Umbran's very nice explanation, I'd mention that you can't say one particle has property x and the other has property -x but no one knows which until measured. Really, neither particle has either definite property at all until it is measured!

 

[freyar]

There is a fundamental issue we face in this discussion.

It is not sufficient to say, "Hey, if I bend and flex this analogy a bit, it seems a bit like the real world!" So, cool! This is not a useful test of your theory. There is no point in considering a new model for the universe, unless it changes something. Finding another model that is also consistent is merely evidence that the two models are somehow equivalent, which is usually not very interesting. Kind of like saying, "Hey, 2+2 = 4, and 2 * 2 = 4! Isn't it cool that my multiplication gets the same result as your addition!!" What we then have is merely a cherry-picked instance where they happen to be the same thing, not the discovery of a major underlying principle.

If I had a nickel for every time someone has called me out of the blue, emailed, or even walked into my office with an analogy or similarly vague idea about physics, I'd be a rich man. So, yes. Not that I would discourage anyone from thinking about this sort of big question and what analogies might be helpful for understanding something, but please also don't underestimate the amount of work that goes into developing a physical model or theory.

In the process of science, if we have a model of the universe, and we want to see if it is true, we have to find something that model predicts that other models do not, and we test for that. This is a problem with what is commonly called, "string theory" the more popular class of possible solutions for marrying gravity and quantum mechanics in high energy physics and cosmology. String theories have an issue in that they haven't to date given us any testable results.

This is (mostly) true, but I think it's fair to add that part of the scientific process to build on previous knowledge in areas that are for technological reasons currently untestable. String theory does that in a highly mathematically consistent way which other theories of quantum gravity do not. And, in principle, it can make predictions, though string theory is an awfully complicated framework, so it's hard to know what the likely predictions are. So it's rather unfair to dismiss string theory as unscientific, like some people do (I'm not saying that Umbran is doing this, of course). The other thing with string theory is that it actually does make predictions in arenas other than the ultimate explanation of quantum gravity and early universe cosmology of our universe. Specifically, string theory in certain situations turns out to be identical to theories of particle physics that are very similar to nuclear physics, and string theory has led to qualitative understanding of some otherwise confusing experiments in nuclear physics. (They're not quantitatively precise because the theories in question are not quite the same as real nuclear physics, but they are similar.)

 

[Umbran]

Regarding dark matter and dark energy, no, we don't know specifically what they are, but that's mostly a matter of specific theories.

And, just because, I'd like to point out that the post you're replying too actually said, "And since I haven't heard explanations lately for where all the universe's dark matter is hiding..."

The funny bit is that the actual question of *where* it is is part of the reason for thinking it exists at all! We can observe motions in the universe, and see that they are not consistent with the visible matter, and thus deduce the presence of matter that isn't glowing (is "dark") in those places. We know *where* it is (as in, say, the halo of galaxies) much better than we know *what* it is.

 

[Dannyalcatraz]

[NU][/NU]I'm thinking it's the corpses of dead cats in boxes. But my thought processes might be a little fuzzy on this...

 

[Umbran]

This is (mostly) true, but I think it's fair to add that part of the scientific process to build on previous knowledge in areas that are for technological reasons currently untestable.

Quite true. But, until such time as it gives us new testable predictions, it is not giving us much actual knowledge of the physical universe. String theories have advanced the fields of mathematics far more than those of the physical sciences.

String theory does that in a highly mathematically consistent way which other theories of quantum gravity do not. And, in principle, it can make predictions, though string theory is an awfully complicated framework, so it's hard to know what the likely predictions are. So it's rather unfair to dismiss string theory as unscientific, like some people do (I'm not saying that Umbran is doing this, of course).

It is untested. It has remained untested for a long time. For decades, some very bright minds have been barking up the tree, and no sign of a squirrel. I begin to think that maybe we should try other trees, because these really aren't getting us anywhere. There's probably a good argument to be made that continued fascination with this untested category of theory is getting in the way of finding a theory that does make testable predictions - that's not so much saying it is unscientific, as it is saying that it is unfruitful science.

Moving forward as if it were tested science would be unscientific. Right now, it is more like mathematical noodling about to see if there's something there we might use. So far, I am unimpressed with it as a physical model. Some very pretty math in there, though.

The other thing with string theory is that it actually does make predictions in arenas other than the ultimate explanation of quantum gravity and early universe cosmology of our universe. Specifically, string theory in certain situations turns out to be identical to theories of particle physics that are very similar to nuclear physics, and string theory has led to qualitative understanding of some otherwise confusing experiments in nuclear physics. (They're not quantitatively precise because the theories in question are not quite the same as real nuclear physics, but they are similar.)

Well, yes, but that's kind of like saying that Special Relativity reduces to Newtonian mechanics for low speeds. Matching up with already measured cases is a prerequisite. There were many versions of string theories that got tossed out because it was found they *didn't* reduce to the known particle physics - I know of several such efforts that were stillborn and never published for this reason.

 

[GMMichael]

Here's a thing: The problem that you describe, of latency between clients, is exactly what is spookily solved by entanglement. Two particles are emitted, with balancing properties. One heads to the left, the other to the right. You might expect that the selection of which particle went in which direction to be set at the point of emission, but, it works out that decision isn't made until one of the particles is observed.

Yeah! Funny how these particles don't have a definite state until they're far enough away from each other that they seem to break light speed to resolve their states. Seems like something a host-system could do though, huh?

There is no point in considering a new model for the universe, unless it changes something. . . There is never a time when we disagree on what is going on in the universe.

Right. A meta-question of mine is "does this model break down under what we already know?" The follow-up is "does this model change something?" Where it might change something is that it's a different take on "many worlds," in that the different worlds have some impetus to bend a bit, and agree with each other. Sort of like if Schroedinger's cat lives in one universe and dies in the other, then universes parallel to the "live" universe are somehow influenced toward the cat surviving.

Sure, there is never a time when we disagree on what is going on in the universe - if we are in the same universe. When two observers, moving relative to each other, disagree on when something happens or what time it is, that would be disagreement. But do they have the same client, or are they using different clients?

As Umbran mentioned above, events that can communicate with each other always stay in the same order. So, since I can tell myself "ow, I've been shot in the leg," those two events stay in order. Here's how I teach this in class: If two events happen at the same place relative to some person, they have a past-future ordering. So, relative to me, getting shot and getting behind cover happen at the same place--- at me. So they have order.

Sure. Relative to you, they have past-future ordering. The different-clients idea suggests, though, that there are more than one person; there's more than one observer. See, now I'm wondering: does the state of science today assume that there is only one observer (since all events are consistent and cannot be disagreed upon), and that one observer is "ME?" Or to put it another way, do we still think that the sun revolves around us?

 

[Umbran]

Yeah! Funny how these particles don't have a definite state until they're far enough away from each other that they seem to break light speed to resolve their states. Seems like something a host-system could do though, huh?

Except the distance is irrelevant. You can have entangled particles close together, too, for which no host is required.

Sure, there is never a time when we disagree on what is going on in the universe - if we are in the same universe. When two observers, moving relative to each other, disagree on when something happens or what time it is, that would be disagreement. But do they have the same client, or are they using different clients?[/quoite]

A disagreement on what time an event occurred is not material - we can disagree upon that if we are standing next to each other, neither of us is moving relative to one another, and my watch is 2 minutes fast.

A disagreement on *what happened in the event* is material. And those don't seem to occur.

Sure. Relative to you, they have past-future ordering. The different-clients idea suggests, though, that there are more than one person; there's more than one observer. See, now I'm wondering: does the state of science today assume that there is only one observer (since all events are consistent and cannot be disagreed upon), and that one observer is "ME?" Or to put it another way, do we still think that the sun revolves around us?

Relativity is largelly about how two different observers view the same events.