Quantum Physics Abused Why We Need DrW Around Here

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_DrW
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Re: Quantum Physics Abused Why We Need DrW Around Here

Post by _DrW »

Gadianton wrote:i even have an argument to justify why there is no point in trying to know; maybe will post later.

This ^ I would like to hear.
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Re: Quantum Physics Abused Why We Need DrW Around Here

Post by _Res Ipsa »

DrW wrote:
Gadianton wrote:
i even have an argument to justify why there is no point in trying to know; maybe will post later.

This ^ I would like to hear.


Me too!
​“The ideal subject of totalitarian rule is not the convinced Nazi or the dedicated communist, but people for whom the distinction between fact and fiction, true and false, no longer exists.”

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Re: Quantum Physics Abused Why We Need DrW Around Here

Post by _Analytics »

Physics Guy wrote:I'm about as good an expert on quantum measurement as you're likely to find. My name is on some significant papers about environment-induced decoherence, and I once held a US visa for the stated purpose of "investigating the effects of quantum mechanics on the universe." That was just a bureaucrat's garbled phrasing but I actually was doing a post-doc for related stuff.

I don't know what's going on with quantum measurement, and I don't believe anyone else really does, either. In the 1990s multiverse interpretations—"Many Worlds"—were a fad among hungry young post-docs who were embracing a startling idea in order to show off how brilliant they were, and I think the current wave of endorsement of this in popular science is just the afterglow of that old fad. I was unimpressed even then, for two basic reasons.

Firstly, there's a ton of evidence for something like wave function collapse apparently happening, but it's all about microscopic events with just a few photons or electrons really involved....

Thank you so much for weighing in--I can't help but think you are right. I try to keep an open mind about such thing; I try not to insist that the universe conform to my own personal prejudices. But I can't help but think that whatever's going on, entire universes aren't literally spawning into existence at a exponentially increasing rate.
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Re: Quantum Physics Abused Why We Need DrW Around Here

Post by _Doctor CamNC4Me »

DrW wrote:
Doctor CamNC4Me wrote: If I'm wrong feel free to correct me, but space itself moves FTL.
- Doc

Doc,

Space isn't actually moving as much as it is expanding. As described on another thread, the rate of expansion is 68 km/s per megaparsec.

That means if one were to put a point on a star map one megaparsec from Earth, that point would be receding from Earth at a speed of 68 km/s, or very roughly 152,000 mph. The speed of light is 3.0 x 10^8 m/s.

A parsec is about 3.6 light years or about 31 trillion km. A magaparsec would be a million times that or about 3.6 million light years.

By my calculations, a galaxy would need to be roughly 4,400 megaparsecs (or roughly 15 billion light years) away from Earth before it would be receding at the speed of light.

The visible universe is approximately 46 billion light years across, so galaxies receding at the speed of light are a long way out there. By comparison, our local group of galaxies is about 10 million light years across.

Also remember that FTL refers to the local speed of light. While a galaxy 15 billion light years from us may be receding at more than 3.0 x 10^8 meters per second, its speed in a local inertial frame is nothing close to that.
________________________

*Just read a more recent estimate that increased the rate of expansion from 68 to 71 km/s per megaparsec. So, let's round off to 4000 megaparsecs, or about 13.5 light years out before a galaxy is receding at the speed of light.


I wonder what's causing the acceleration of space itself. I was watching this:

https://youtu.be/QAa2O_8wBUQ?t=188

because I need cartoons to grasp abstract concepts, and have so many questions. So, if the universal expansion is happening at X-rate and is increasing I suppose it doesn't really matter what the speed is in context of this thread because our ability to observe the known universe is still limited by our isolation.

Maybe that's what Gad is getting at... That's it's pointless because according the to the biological imperatives by which we live and through which we observe we're limited and eventually we're left to die.

I don't know. I'm just typing at this point.

Here's hoping our transcendence to AI opens up some doors!

- Doc
In the face of madness, rationality has no power - Xiao Wang, US historiographer, 2287 AD.

Every record...falsified, every book rewritten...every statue...has been renamed or torn down, every date...altered...the process is continuing...minute by minute. History has stopped. Nothing exists except an endless present in which the Ideology is always right.
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Re: Quantum Physics Abused Why We Need DrW Around Here

Post by _Symmachus »

Physics Guy wrote:Natural theology has its high points and low points. Big Bang cosmology looks awfully nice for theology; Darwinian evolution of nasty parasites, not so much. Quantum measurement is just neutral, I'd say, because our current understanding of quantum measurement is about like the understanding of gravity held by Plato and Aristotle. They could have debated long and hard about whether higher or lower regions were the proper spheres of earth or fire, but all their philosophizing was really pointless, because there were too many essential facts that they just didn't know. We're like that now, with quantum measurement.


I think that's where theology finds an opening. Theological arguments tend to be most appealing in those areas where there are no alternatives or where the alternatives are also open to serious doubt (i.e. what happened before the big bang). Demon theory, for example, was once a dominant mode of understanding and treating illness in Europe that gave the more "scientific" humorism a run for its money, but neither have fared well since the advent of germ theory.
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Re: Quantum Physics Abused Why We Need DrW Around Here

Post by _Physics Guy »

My impression from limited reading in the history of medicine is that the victory of germ theory over humorism (the mechanistic theory that illnesses were imbalances in the proportions of bodily fluids) was made much harder by the fact that germs sounded so much like demons: invisible life forms that could invade the body from unclean objects or people but could be thwarted by ritual cleansing. The humors theory was indeed much more rational and scientific, and germ theory seemed like a perverse step backward into the benighted past. Big Bang cosmology also had a hard time gaining acceptance over the prior scientific assumption of an eternal universe because it sounded too much like creation ex nihilo.

Putting the ideological cart before the observational horse is a temptation to everyone, not just theologians. It's not necessarily even a bad thing. Constructing and testing new theories is hard work, and asking people to do all that work without the potential reward of confirming their ideological hopes is like asking entrepreneurs to take risks without profit. It's not all bad for the old theories to have ideologically committed supporters, either. The adversarial system is good for threshing out errors.

So I don't see anything so wrong with theologians trying to mix it up with science, as long as they are clear about the difference between the front end of science, where the search for truth has few rules, and the back end of science, where textbooks emerge with known facts. The trouble comes when someone plays by the nearly nonexistent rules of front-end science, but then claims the authority of back-end science. It can be hard for the general public to tell when this happens, partly because popular science media often greatly exaggerate the solidity of current speculations.
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Re: Quantum Physics Abused Why We Need DrW Around Here

Post by _Gadianton »

Re: an argument to justify why there is no point in "trying to know"

Wasn't feeling too well when I wrote that and it came out a little more ambitious than I intended. Better would be "comprehend".

Part 1: Richard Feynman says "shut up and calculate" about quantum mechanics. In one of his classroom videos, he says he doesn't understand it. One thought is the next Feynman might find the way to make proper sense of it. My belief is "not going to happen".

Part 2: Things we think make sense don't really "make sense" either.

Example:

We typically think of bouncing balls as intuitive and electricity and magnetism are more abstract. But really, a ball bounces thanks to "clashing" (there's that fiction again) electron shells which is anything but straightforward to visualize. So it really isn't very intuitive that a ball bounces, it's just we're used to seeing a cause and effect without gaps from our sensory vantage point and accept as obvious.

Example:

Some weird alien life out there might "see" magnatism and build weird models based on magnatism in order to make bouncing balls intuitive. And so reducing deep principles to what is intuitive is mostly self-deception -- re: building a "picture of reality"

Example:

Take something moderately deep like relativity. It's mind blowing to contemplate a vehicle driving by and shining a flashlight ahead and then behind, and the point is that the light travels the same speed with respect to the car and to observers both ahead and behind. The faster the car, the more mind-blowing it is to imagine.

But change the car to a science lab sealed with 4 walls and an overhead light hanging from the ceiling inside, and it's intuitive to reject the suggestion that an observer on the ground might say, "gee, any light and magnatism in that lab is going to take fore-e-ver to propagate to the guys standing toward the back." The faster the lab is moving, the more obvious it is. Now relativity makes lots of sense.

The first experiment primes our intuition to think of a gun firing from a car and we want to add or subtract the car velocity. The second primes our intuition to think of the inside of a room where we imagine the occupants feel at rest and so everything should be "normal". But neither tells us any more than the other about the reality of the principle, and if we buy into relativity a little bit more thanks to the second example, we see the degree to which we're led down the garden path:

intuition -> understanding -> knowledge

It's pretty easy to see the point of the Feynman quote and decouple understanding from knowledge to a degree. Breaking intuition away from understanding feels a little more severe because then what we're ultimately comprehending isn't what's really "out there".

It's interesting to note that pseudoscientists often claim deep science is more intuitive than puffed up professors make it. It's part grassroots effort to ground reality into what's easy for humans to visualize. Legit cosmologists outdo each other to come up with analogies and ways to break down difficult concepts, but there is a slight risk here in getting their audience to privilege intuition over evidence, and become targets for pseudoscience.
Lou Midgley 08/20/2020: "...meat wad," and "cockroach" are pithy descriptions of human beings used by gemli? They were not fashioned by Professor Peterson.

LM 11/23/2018: one can explain away the soul of human beings...as...a Meat Unit, to use Professor Peterson's clever derogatory description of gemli's ideology.
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Re: Quantum Physics Abused Why We Need DrW Around Here

Post by _Physics Guy »

I agree with that, and I think it's very insightful.

Popular explanations of science have to try to make scientific ideas intelligible by making them intuitive, and to do that they often use simple pictures. The meta-message which they thereby convey, however, is that intuitive pictures are the end product of science—and that's such a wrong message that the whole exercise often does more harm than good.

Simple and intuitive pictures are used in science all the time, because scientists are, like all humans, simply jumped-up apes who have to try to think with lumps of meat. The simple pictures are always crude mental tools with limited applicability, however. We may think of an elephant as though it were a snake, when we are thinking specifically about the elephant's trunk. If you think that what science tells us about elephants is that they are snakes, though, you will really be wrong about elephants—and about how science works. Simple intuitive pictures are not the goal of science. They're a crutch, and unfortunately our wretched little animal brains cannot do without them.

Feynman himself is a fine case in point. He was always scornful of philosophy and he advocated that we just use quantum mechanics rather than trying to reconcile it with our intuitions. And yet Richard Feynman's great contribution to physics—and it really was a huge one—was to devise intuitive techniques for calculation. The main way he did this was to invent what are called "Feynman diagrams"—a graphical code for certain mathematical expressions that functions rather like a high-level computer language to let one express a lot of small steps in one symbol.

And so now all over the world physicists think about the unimaginable behavior of subatomic particles in terms of little lines and loops that join together according to some pretty intuitive rules. You can think through a Feynman diagram quite naturally as meaning, "The electron goes here and absorbs a photon, then goes there and emits a photon, and then flies out here to the detector." You might well think that quantum field theory is thereby telling us that this is how electrons move; but alas it isn't. That story of how the electron goes here and there, interacting with photons, is not what actually happens, at all. It's just a code that translates in the end to an algebraic expression which is one term in a scattering amplitude. If you add up enough of those terms you can get an excellent approximation for the probability distribution of where electrons actually go. So the intuitive picture is not the theory's meaning. It's just a tool that we use in order to calculate.

That doesn't mean that the quest for intuitive pictures is misguided or hopeless. It's a necessary task, given our limited brains. If we tried to abandon intuitive pictures, we'd be less able to understand the world, not more. It may also be a sufficient task. By skilfully combining different intuitive pictures and using each one where it applies, we have been able to figure out an awful lot of things. To return to the example of bouncing balls versus light waves, Clark Maxwell formulated his field equations and discovered that light was electromagnetic waves. He got there by constructing mechanical models for electric and magnetic fields as distortions in a material medium, the ether, that he conceived as being made of many tiny weights and springs all connected together. This was a good idea because in Maxwell's time mechanics was the most developed part of theoretical physics, so mechanical models were the most powerful conceptual tools to be had. He himself took the ether seriously as a genuine physical object—the largest object in the universe, he once called it, because it filled all of space. He was wrong about that, but his example still shows that intuitive pictures can work very well, as means rather than ends—if you know how to use them.

So I do see good reason to keep on trying to make sense of quantum mechanics in new ways. We may yet learn some new things by doing that. Quantum mechanics is old as a theory now, but in a lot of ways it is still early days yet, because the technology to actually do a lot of the things that have until now been thought experiments is only just coming online.
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Re: Quantum Physics Abused Why We Need DrW Around Here

Post by _DrW »

Gadianton wrote:Re: an argument to justify why there is no point in "trying to know"
<SNIP>

Dean Robbers,

Thank you for taking the time to explain. Can't say much more than Physics Guy in response, except to note that this kind of insight is why we continue to pay you the big bucks around here.
David Hume: "---Mistakes in philosophy are merely ridiculous, those in religion are dangerous."

DrW: "Mistakes in science are learning opportunities and are eventually corrected."
_Gadianton
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Re: Quantum Physics Abused Why We Need DrW Around Here

Post by _Gadianton »

Physics Guy wrote:This was a good idea because in Maxwell's time mechanics was the most developed part of theoretical physics, so mechanical models were the most powerful conceptual tools to be had. He himself took the ether seriously as a genuine physical object—the largest object in the universe, he once called it, because it filled all of space. He was wrong about that, but his example still shows that intuitive pictures can work very well, as means rather than ends—if you know how to use them.


Right. I agree, we're stuck with models and those with a real gift for visualization will make the long strides. I mentioned Relativity thought experiments in a certain critical manner risking it being pointed out that this is precisely how Einstein got to where he did, out thought-experimenting Maxwell and his followers.
Lou Midgley 08/20/2020: "...meat wad," and "cockroach" are pithy descriptions of human beings used by gemli? They were not fashioned by Professor Peterson.

LM 11/23/2018: one can explain away the soul of human beings...as...a Meat Unit, to use Professor Peterson's clever derogatory description of gemli's ideology.
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