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OFSO
12th Mar 2014, 15:21
1) I have been trying to get my head around Quantum Physics theory after reading John Gribbin's "In search of Schröedinger's cat". Are the people who dream up all these theories (Bohr, Jammer, Dirac etc) actually describing what happens, or are they postulating theories and formulae in an attempt to explain what they see experimentally? I suppose what I'm looking for here is an assessment of the accuracy of the explanations I've been reading. "Copenhagen Interpretation" comes to mind, but I'm not sure why.

2) By coincidence (although given quantum theory, maybe not) while I was reading the book the other night I had the TV on (which may account for my lack of understanding of the book's wilder theories) and there was a program narrated by Morgan Freeman, he of the soothing voice, on black holes, wormholes through space and artificially created universes. I heard him say that "most cosmologists now agree that parallel universes exist....."

In this context, what is "most" and if so, where are they ? (The universes, not the cosmologists, whom I suspect are to be found on Friday nights down the pub like everyone else.) MF also said "we can't travel to any of the parallel universes" which if it's true spoils the point of having them created in the first place. So why can't we get there ? Surely Richard Branson could do something, for a price....

Damn, that's three questions.

rgbrock1
12th Mar 2014, 15:35
OFSO:

WTF is wrong with you? I post something about monsters under the bed and you come merrily along and post something about quantum physics? That's just so... so... wrong.

Actually, by the time I got to your third sentence my head exploded, spilling what little brains I have remaining all over my LCD.

I think I'll stick with the theory of monsters under the bed. :ok:

angels
12th Mar 2014, 15:37
Ooops. I appear to have come here by mistake.....:eek:

My apologies. Enjoy your discourse!

MagnusP
12th Mar 2014, 15:42
Perhaps we should have the threads merged, as the monsters under the bed have broken through from a parallel universe. Or maybe the dungeon dimensions. They used quantum to do it. See?

airship
12th Mar 2014, 15:53
So why can't we get there ?

That's an easy one even for airship: Because we're already there...?! :ok:

In the billions of existing parallel universes: I'm variously married to Meg Ryan, Angela Merkel or Tom Clooney; drive (or am driven in) a Rolls, Maserati, Renault or Reliant Robin; reside in a 2,000 acre private domain, 45m² apartment or mud-hut et cetera...

The one constant that I can assure you of is that my contributions, are awaited with bated-breath in discussion forums across all the universes. ;)

PS. Who's the other brainy member you refer to above?

rgbrock1
12th Mar 2014, 15:54
Shhhhh, Magnus. Don't give it away. We still want little kiddies to be scared shit-less of things under the bed. We don't need any reference to this quantum physics tom-foolery to make 'em think different! :ok:

awblain
12th Mar 2014, 15:58
As Mermin, or Feynman, and probably both, addressed philosophical issues of quantum mechanics: "shut up and calculate".

The quantum world is probabilistic. That's how reality is. End of story.

The most natural explanation for the awkward apparent start to our Universe 13.X billion years ago is that there's an evolving multiverse. This can perhaps be tested in principle looking at the large scale structure in the microwave background radiation, but it's a "belief" that these cosmologists would have, rather than strong evidence. Old Fred Hoyle might have been right after all in his epochal fights with everyone (but in the wrong way).

Wrathmonk
12th Mar 2014, 15:59
OFSO

Watch the Big Bang Theory (http://en.wikipedia.org/wiki/The_Big_Bang_Theory) from Season 1 to date and your questions will no doubt be answered (the technical director (http://en.wikipedia.org/wiki/David_Saltzberg) actually knows what he is talking about and one of the actors has a PhD themselves)! And at least it should raise a laugh or two along the way. Not forgetting the easy on the eyes lead actress (http://en.wikipedia.org/wiki/Kaley_Cuoco) either...

rgbrock1
12th Mar 2014, 16:00
Kaley Cuoco certainly does prove the validity of the big bang theory, that's for sure. :}

500N
12th Mar 2014, 16:06
"Two questions to the more brainy members of PPRuNe (both of them)"


AW Blain has arrived so that is one of them ;)


Who is the other ?

rgbrock1
12th Mar 2014, 16:16
Me, 500N. You should know better than having to ask. :}:E

ORAC
12th Mar 2014, 16:18
Are the people who dream up all these theories (Bohr, Jammer, Dirac etc) actually describing what happens, or are they postulating theories and formulae in an attempt to explain what they see experimentally? All models are wrong, but some are useful. (http://telescoper.wordpress.com/2013/05/17/all-models-are-wrong/)

The only complete model of the world is the world - maps, globes, rock samples are only partial descriptions of a small fraction of the whole - but are useful for certain purposes within their known limits.

Similarly all theories such as Newton's, Einstein's, Heisenberg's etc are only partial descriptions of the underlying principles of the universe but are useful within their known limits - e.g. Newton's laws are fine for most things until relativity starts being a factor.

So, in answer to your question - they're models used to understand some of the underlying principles behind what we perceive (had to fit in the observer being an essential part of the process.)

airship
12th Mar 2014, 16:32
At awblain's suggestion, I had a look at the back of my LG microwave. It's a bit dusty that's all. I once had a "Big Bang" which emanated from my older microwave oven (a Whirlpool I think), but that was because I'd inadvertently put a metal dish inside. Maybe I just need a bigger microwave (the LG is only 30L)?

rgbrock1
12th Mar 2014, 16:34
airship wrote:

but that was because I'd inadvertently put a metal dish inside.

Well that's a a relief airship. At least the big bang wasn't caused by your inadvertently drying off one of your pudicats in the microwave. :E

Dak Man
12th Mar 2014, 17:20
There was an interesting scientific discussion last year regarding absolute zero, whereby it was postulated that a shift in temperature to "below" absolute zero was in fact a shift to infinitely hot.

I pondered that if before time (as we know it) existed and the universe (as it existed before the BB) was at absolute zero. What if, given the circular nature of temperature as described in the article, some quantum event caused the temperature "clock face" to momentarily run "anti-clockwise" into infinitely high temperature, could that have been causal of the big bang and hence the catalyst for, well, everything else????????

here's the article.

Quantum Gas Temperature Drops Below Absolute Zero - Wired Science (http://www.wired.com/wiredscience/2013/01/below-absolute-zero/)

bnt
12th Mar 2014, 17:46
It was called the Copenhagen Interpretation for a reason: it wasn't all that clear what the maths meant in the real world, if anything. The story behind quantum theory in general is quite complex, and I don't get it all but I know that it started with Max Planck determining that light was made up of particles (quanta) and wasn't continuous "light". It turned out to be a good explanation for why the universe wasn't one big explosion (the "ultraviolet catastrophe (http://en.wikipedia.org/wiki/Ultraviolet_catastrophe)"), and further experiments confirmed that energy was indeed quantised.

PS: Werner Heisenberg* developed his Uncertainty Principle (http://en.wikipedia.org/wiki/Uncertainty_principle) to describe how, at the subatomic scale, we really can't know "what happens" in ways familiar to us. For an electron (for example, properties such as "speed" and "position" are no longer finite quantities, but probabilities.

* if that name seems familiar to watchers of a certain US TV series, well, that character's choice of alias was not a coincidence.

Dont Hang Up
12th Mar 2014, 17:59
Meanwhile back at the original question...

Quantum Physics is generally held to be "real" because, despite its many counter-intuitive effects it is a powerful predictive tool and many practical outcomes arise from it (including much of electronics). That does not mean there may not be a deeper explanation still to be found, it just means that it is the best model we have.

Parallel universes on the other hand (multiverse is the fashionable term) are very much a different issue. It seems largely a consequence of the failure String Theory (which has been floundering for a decade or more) to predict anything.

The Multiverse is a completely unprovable conjecture which unfortunately many physicists seem to be clinging to as a get-out-of jail card for String Theory whilst an equal number of others think its utter b****cks.

The Multiverse is very much like a scientific religion. It can be used to explain just about anything and it can never be disproved. That alone should be enough to make one sceptical.

You can find the ultimate sceptic here...
https://www.math.columbia.edu/~woit/wordpress/

BOAC
12th Mar 2014, 18:07
Anyone else not sure about the Uncertainty Principle?

WeeJeem
12th Mar 2014, 18:24
1) I have been trying to get my head around Quantum Physics theory after reading John Gribbin's "In search of Schröedinger's cat". Are the people who dream up all these theories (Bohr, Jammer, Dirac etc) actually describing what happens, or are they postulating theories and formulae in an attempt to explain what they see experimentally? I suppose what I'm looking for here is an assessment of the accuracy of the explanations I've been reading. "Copenhagen Interpretation" comes to mind, but I'm not sure why.

At one level, it's "classic" loop of scientific method: (observe, hypothesise, predict, experiment, interpret).

On another level, it's an area where personal attributes like "intuition", "common sense" and the like can be much more of a hindrance than a help.

The cat-in-the-box routine falls down typically because there's a lot of fudging around words like "measurement" and "observer" - such words are loaded because they're typically assumed to refer to someone opening the box, rather than something in the box interacting long before the box is "opened", ie classical interpretations being applied to things that also require to be examined in a quantal context.

HTH :O

grizzled
12th Mar 2014, 18:49
BOAC...

:D

Best post of the day (on all fora)!

sitigeltfel
12th Mar 2014, 18:52
The answer to all three questions, as any full no, is ..........42!

rgbrock1
12th Mar 2014, 18:52
BOAC wrote:

Anyone else not sure about the Uncertainty Principle?

Hm. Um, I'm not certain. :}:E

OFSO
12th Mar 2014, 18:57
I pondered that if before time (as we know it) existed and the universe (as it existed before the BB) was at absolute zero.

Now that must have been one heck of a huge electricity bill. Even bigger than my two month bill which arrivd at the end of February and was €3500....a mistake in meter reading, unless someone has tapped the wires leading to my house in order to start up a fresh universe.....aha ! So that ¡s what that glowing thing under the bed is.

Windy Militant
12th Mar 2014, 20:08
I thought Planck's constant meant that my bit of wood was the same thickness all the way along. :(

I know hat, coat, linac etc.

broadreach
12th Mar 2014, 20:24
I'm afraid Arcniz has captured the other one and is displaying it on the Black Box thread, Post No. 36.

awblain
12th Mar 2014, 20:34
Dak man,

An inverted population of states can be described as a negative temperature, but just in that part of the laser, not the Universe as a whole or even the laser as a whole.

Mr Optimistic
12th Mar 2014, 20:36
Listen its all maths. In an attempt to get concepts across they tried to come up with analogies like that f*ing cat. Einstein would not accept an uncertain and probabilistic basis for reality. The uncertainty principle is a bit of an arm waving inequality which puts limits on certainty.

Fox3WheresMyBanana
12th Mar 2014, 20:44
1) The development of Quantum Theory had all the aspects you mention. Einstein's quantum theory (The Photoelectric Effect) was a suggested (heuristic) means to describe the observed behaviour of electromagnetic waves, based on the work of Max Planck. Einstein got the Nobel Prize for this. Robert Millikan then spent 11 years trying to disprove Einstein, and failed so successfully (i.e. proved Einstein right beyond doubt) that he got a Nobel Prize 2 years after Einstein. Dirac came up with the Quantum Theory of the Electron to explain how the relativistic motion of the electron could fit both Einstein's theories of the Photoelectric Effect and Special Relativity. At his Nobel Prizegiving, he speculated that the negative solutions to his equation allowed the possibility of a whole new group of antiparticles. Carl Anderson discovered the first of these - the positron (antielectron) a few years later.

In summary, some parts were theories looking for observational proof, some the reverse, and some were almost accidental combinations of both aspects.

2) "most cosmologists now agree that parallel universes probably exist....."

3) which if it's true spoils the point of having them created in the first place. So why can't we get there ? Point? Assuming there's a point is very brave. Explain the 'point' of Piers Morgan :mad:. Created? Are we bringing God into this? :eek:

Heisenberg was uncertain about everything, but his formula tells you the minimum level of uncertainty in a situation. Mileage,as they say, may vary. ;)

BenThere
12th Mar 2014, 21:33
The problem I've faced is that even though I've figured everything out and can provide a clear path to save the world, I have trouble convincing the rest of humanity.

Can someone help me out here?

Fox3WheresMyBanana
12th Mar 2014, 21:34
Are you sure they're all human?

awblain
12th Mar 2014, 21:37
That "we had to destroy the village to save it…" argument works no better now than it did in the Sioux nation or in Vietnam…

BenThere
12th Mar 2014, 21:42
"We have to pass this bill so we can find out what's in it."

Similarly, awblain, we are in the process of destroying America. But for what? To save it?

Mr Optimistic
12th Mar 2014, 21:59
There must be a reason why awblain lives in Pasadena, perhaps on Los Robles so he should know.

awblain
12th Mar 2014, 22:06
we are in the process of destroying America. But for what?

Good question. Just as soon as you and your baggerlooney associates work that one out, we'll all be a whole hell of a lot better off.

Mr Optimistic
12th Mar 2014, 22:10
Perhaps this all an expression of the human desire for certainty, a return to a mother's comforting arms. The priest with faith used to provide this, poor old quantum physics can't. Most questions can't be answered.

BenThere
12th Mar 2014, 22:18
Just as soon as you and your baggerlooney associates work that one out, we'll all be a whole hell of a lot better off.

But we (I prefer to be called a conservative rather than a baggerlooney) don't have the power, you do.

And the demographics for Democrat control well into the future are insurmountable if people, including blacks and latinos, don't come to their senses and realize their alliances with Democrats have been counter-productive.

And there's that old canard about running out of other peoples' money.

Heckuva job, Barry!

Mr Optimistic
12th Mar 2014, 22:26
The natural end point of democracy?

TomJoad
12th Mar 2014, 22:32
Anyone else not sure about the Uncertainty Principle?

That depends on what you mean by anyone and unsure: sometimes I'm unsure and know who I am, while sometimes I'm sure but don't know who I am. I never seam to get both states in superposition:}

BenThere
12th Mar 2014, 22:35
Maybe it is.

It was always reliant on an informed and educated electorate. We've been slack in that regard.

Mr Optimistic
12th Mar 2014, 22:40
1) Physics only claims to provide a model of reality. As was once said 'an electron is an electron' so don't ask if it has a spare bedroom with en-suite.
2) &3) Don't listen to cosmologists. They don't know and will never know.

Try John C Slater Concepts and Development of Quantum Physics or Enge Wehr and Richards Introduction to Atomic Physics.

Fox3WheresMyBanana
12th Mar 2014, 23:19
Curioser and curioser, cried Alice

BBC News - Charlotte Church plans to study for degree in physics (http://www.bbc.com/news/uk-wales-26548241)

awblain
12th Mar 2014, 23:21
As Prof. Cox might have said… things can only get better.

tony draper
12th Mar 2014, 23:29
Some are coming round to the idea that none of it is real, including us, we are just sprites tootling round in a virtual universe, a bit like the Matrix, but the real we int lying in bathtubs full of amniotic fluid with pipes up our arses so nobody is going to come round and unhook you,we are just magnetic pits in some vast hard disk or memory stick.
:rolleyes:

Mr Optimistic
12th Mar 2014, 23:30
AW come on awblain is it JPL or CalTech?

Dushan
13th Mar 2014, 03:51
Good question. Just as soon as you and your baggerlooney associates work that one out, we'll all be a whole hell of a lot better off.

We have. It is you and your loony left that is destroying America.

TWT
13th Mar 2014, 04:09
Hmmm.I can't make up my mind whether I'm indecisive or not :confused:

vulcanised
13th Mar 2014, 14:02
I can't make up my mind whether I'm indecisive or not


I will be addressing that very issue as soon as I get over my frenzy of indifference.

OFSO
13th Mar 2014, 14:15
Well, don't put it off too long or you will be either procrastinatory or indifferent - if you can ever decide ! Or like the quantum photon - both at the same time.

Blacksheep
13th Mar 2014, 14:22
What we need is more scientists (or wizards) like Mr. Terence Pratchett, who has experimentally determined that Schroedinger was quite wrong.

The cat actually exists in three states:

Alive
Dead
Very, very angry
One opens the box with extreme caution. :uhoh:

OFSO
13th Mar 2014, 21:46
The cat actually exists in three states:

"existing in three states" implies that it is one of them to the exclusion of the other two. Quantum theory says it may be in more than one state at once. Although "dead" + "angry" seems less likely than "alive" + "angry"*.

In fact there is also a fourth state: if you (or somone else) are not observing the cat, then the cat isn't there at all.

*A more likely state is "alive" + "hungry". All cats are in this state most of the time, when they are not in the state denoted by "alive" + "simulating hunger but when offered food will turn nose up and walk away in feigned distaste". Again this last NEVER happens when an observer isn't present.

airship
13th Mar 2014, 22:09
Blacksheep wrote: 3. Very, very angry

Like this Himalayan pudicat (http://www.bbc.com/news/blogs-magazine-monitor-26544284) in USA: When the child's father Lee Palmer struck the four-year-old animal on the rear in retaliation, it began charging at the family, forcing them to take refuge in their bedroom. In earlier reports, I even read that the father had "kicked" the cat... :\

Whatever, I don't believe it's pudicats who're "holding back" in some (or any) ways, any valuable research into quantum physics or whatever. Most pudicats are very suppurrrrtive of most human-beings' endeavours, provided that their carers are kind and attentive to their most basic demands. And wouldn't mankind be "better off" if all these brainy scientists were to dedicate their wisdom to the design and manufacture of the "ultimate croquette" (for cats or dogs)...?!

OFSO
13th Mar 2014, 22:23
I don't believe it's pudicats who're "holding back" in some (or any) ways,

Imagine, if you will, two cats that are studying quantum physics. I know, I know, it requires some imagination, but bear with me. So they devise this experiment which requires placing a human in a box with a radioactive isotope which as it decays will release some kind of poison fatal to humans at some random time. The cats sit and watch, wondering when to open the box. Then, in the next room, someone places on the floor two plates of boiled chicken, not too hot. One is breast, one is a leg. The door between the two rooms, the one containing the plates of chicken and the one containing the box and the humans and the cats, is then opened. Outside the building where this is taking place is a hen run, containing a hen which is the cooked chicken's mother. Now, see where I'm going with this experiment ?

None of the participants is observing any of the others*, so none of them actually exist.

* Except possibly cat "a" which of course wants the food on the plate of cat "b" and is watching it to see if its attention slips for an instant. So only the two cats exist for each other. The other participants are in a state of flux, which is a rude Japanese word for sexual intercourse.

Have I made my case ?

airship
13th Mar 2014, 22:53
OFSO, I believe you lost your argument (or whatever it was) when you wrote: ...bear with me Bringing bears into this doesn't help much (survival rates of bears newly-introduced into the French-side of the Pyrénées between Spain and France are almost zero). :sad:

Cats come and cats go. Some of them stay with you all their lives, and you eventually bury them. Others visit, stay awhile, before disappering without trace (like MH370). I always wonder where (and how) they died.

As human-beings go, there's nothing wrong with posing all these difficult questions. But a simple pudicat might say: "Hey! Get away from the PC! Come give me a rub under my chin...?! It'll bring me some pleasure, reduce your own stress and eventually result in a better World (for us pudicats)"... :ok:

PS. How goes the "little cat" which you sometimes refer to elsewhere...?!

OFSO
14th Mar 2014, 08:31
How goes the "little cat" which you sometimes refer to elsewhere...

You mean Beyoncé, the black single lady. She goes well.

G0ULI
14th Mar 2014, 09:09
Put cat in a box. Lock box. Set poison mechanism. Get a dog!

Avtrician
14th Mar 2014, 10:52
Schröedinger's cat walked into a bar and din't...

:sad:



OK, Hat Coat... Exit stage left..:hmm:

Keef
14th Mar 2014, 11:00
Schrödinger's puditat is stalking the blackbirds in my garden at the moment. I'm uncertain whether or not to go and chase it away (or flip it to its other state).

I first came across the "multiverse" argument years ago with a famous atheist trying to get out of a corner in some convoluted argument to disprove God. I think the multiverse concept was invented to explain why all the umpteen cosmic constants are exactly what they are and need to be for intelligent life to exist (well, relatively intelligent).

PTT
14th Mar 2014, 14:11
An old one:

Heisenberg and Schrödinger get pulled over for speeding.
The policeman asks Heisenberg "Do you know how fast you were going?"
Heisenberg replies, "No, but we know exactly where we are!"
The officer looks at him confused and says "you were going 108 miles per hour!"
Heisenberg throws his arms up and cries, "Great! Now we're lost!"

The officer looks over the car and asks Schrödinger if the two men have anything in the boot.
"A cat," Schrödinger replies.
The cop opens the trunk and yells "Hey! This cat is dead."
Schrödinger angrily replies, "Well he is now."

PTT
14th Mar 2014, 14:12
some convoluted argument to disprove GodNot possible. Fortunately, not necessary, either ;)

OFSO
14th Mar 2014, 15:06
some convoluted argument to disprove God

Just who is this argument with, by the way ? Interestingly God or his manifestation in human form, Jesus, is the one entity to whom faith is denied .

tony draper
14th Mar 2014, 15:53
This is much better than 'Is it a wave or is it a particle', Is the mog a moggy or a late moggy nonsense, one has lost all interest in that stuff of late,
This stuff is much more interesting,something a chap could do in his shed, not scribbling symbols on a bloody blackboard like a big girls blouse.
Throw the bloody chalk away and get back into your shed and do stuff you might just get us to the Stars!!
:rolleyes:
Levitating Superconductor on a Möbius strip - YouTube

MagnusP
14th Mar 2014, 16:17
This is much better than 'Is it a wave or is it a particle',

Prof. Norman Feather of Edinburgh Uni about half a century ago used to tell his students that on Monday, Wednesday and Friday it was one, and on Tuesday and Thursdays it was to be regarded as the other. His book "Vibrations and Waves" was part of my course reading (although I was at the "plebbier" Heriot-Watt Uni).

Fox3WheresMyBanana
14th Mar 2014, 17:13
JJ Thomson won his Nobel for showing the electron was a particle. His son GP Thomson won a Nobel for showing it was a wave.
Bet they were insufferable over Xmas dinner ;)

"Wave"
"PARTICLE"
"Wave, wave, wave, with Bells on!"
"Particle, doubled, and no returns!!"

OFSO
14th Mar 2014, 18:35
Flight MH370 is proving a real-life example of Schrödinger's cat. While it remains unfound (and hence unseen) the crew and passengers are neither alive nor dead but in an in-between state. They will only be in one state or the other when the aircraft is found.

Mr Optimistic
14th Mar 2014, 19:18
Best stop looking then as the finder would be the murderer.

bnt
14th Mar 2014, 21:30
JJ Thompson won his Nobel for showing the electron was a particle. His son GP Thompson won a Nobel for showing it was a wave.
Bet they were insufferable over Xmas dinner ;)

Particularly if you spell their names incorrectly: it's Thomson without the P. Like the airline, and the publishers, and the French electrical company.

Of course, there wasn't really any argument to be had, since GP really helped to prove that De Broglie was right about wave-particle duality. It's a wave and a particle, with both sets of properties being visible and correct under different conditions.

awblain
14th Mar 2014, 23:19
Right you are, bnt.

And it's spelled the same way as Kelvin's Thomson too to avoid confusion.