The nature of the universe.

blu3cat

Right, you asked for it.

Here's a thread about Quantum Mechanics & metaphysics.

Picking up from what was going on in a RLJ thread (http://www.bikeradar.com/forums/viewtopic.php?t=12641153&postdays=0&postorder=asc&start=0) the collective physics borg of cyclists wil attempt to answer any questions about the nature of the universe.

In theory a thread to talk b*lls on.

So to start here's the very famous Schroedinger's cat (shortened)

Said cat sits in a sealed box, inside the box is a poison with exactly 50% chance of being released within 1 hour. So the question is without looking what state is the cat in after exactly 1 hour? Is it alive or dead? (no peeking inside the box).

And as a bonus: How do you know the sun will rise tomorrow.

dennisn

blu3cat wrote:

Right, you asked for it.

Here's a thread about Quantum Mechanics & metaphysics.

Picking up from what was going on in a RLJ thread (http://www.bikeradar.com/forums/viewtopic.php?t=12641153&postdays=0&postorder=asc&start=0) the collective physics borg of cyclists wil attempt to answer any questions about the nature of the universe.

In theory a thread to talk b*lls on.

So to start here's the very famous Schroedinger's cat (shortened)

Said cat sits in a sealed box, inside the box is a poison with exactly 50% chance of being released within 1 hour. So the question is without looking what state is the cat in after exactly 1 hour? Is it alive or dead? (no peeking inside the box).

And as a bonus: How do you know the sun will rise tomorrow.

Well, from the sounds of some previous posts the sun NEVER shines in the UK. So mute
point. At least to me here in the States.

blu3cat

Well, from the sounds of some previous posts the sun NEVER shines in the UK. So mute
point. At least to me here in the States

it still seems to rise behind the big grey raining clouds though, but how do I know that I can expect it tomorrow.

teagar

blu3cat wrote:

Well, from the sounds of some previous posts the sun NEVER shines in the UK. So mute
point. At least to me here in the States

it still seems to rise behind the big grey raining clouds though, but how do I know that I can expect it tomorrow.

You can't "know" anything in the future in the strictest literal sense.

Realistically however, you can look at the history of sun rises and see that in no time whatsoever has the sun not rising in human record.

Thus you can predict beyond any reasonable doubt that the sun will rise. So in any normal use of the word "know" you could "know" the sun would rise, but not in the strictly literal sense

Red Rock

Chances are the sun will rise for you tomorrow, if not I'm guessing you died along with the cat you suffocated to death in that little box you sealed it in.

mba007

From a philosophical perspective just because the Sun rose today doesn't mean it'll rise tomorrow. Something could change that only happens once in an infinite amount of time hence is unpredictable and unexpected. We can only hope the Sun rises tomorrow otherwise our theories have a significant hole.

Thus speaks an astrophysicist!

SteppenHerring

Science works by taking observations and then coming up with a theory to fit them. It might not be completely correct - for centuries, Newton's theory of gravitation worked well enough but then people noticed an anomaly in the orbit or Mercury. Einstein's general theory of relativity explained that and is now our current best model of gravitation, but it doesn't fully explain the observed movement of some distant supernovae.

(As a side note, this is one reason why creationism etc. are crap - because they start with a theory and try to find facts to fit it)

Regarding Schroedinger's cat, well yes quantum superposition (the ability of a particle to be in more than one state at the same time) is an observable phenomenon. Whether this extends to the macroscopic cat is a completely other thing.

WRT the sun rising tomorrow: well, the current best theory is that the sun is a f******g big hot ball out there and we are on the surface of another ball that turns around every 24 hours or so. This theory fits all the observable facts, but may have to be revised should the sun not rise tomorrow (the other reason creationism is stupid - facts change, theory changes).

Yes, I have been drinking.

pinno

I'm worried about the cat - its been more than an hour.

God and the "IF" principle. No, I have not been drinking. This is my theory:

If I said to a creationalist, God is a chocolate teapot, they would automatically assume I was both wrong and nuts. Then I would say "Well, its circumnavigating the globe, its very small and dark, so small that you ca't even see it!" (John Betjemin, I can't spell). After much preambling, eventually they would say "prove it", to which I would reply "Prove that it is'nt there", to which they would have no answer. That is the basis of the existance of God - no one has seen him so therefore you cannot prove that he does not exist. Logic illogic.

Now, the IF principle: Health and Safety personnel run around saying in any given situation "what if"....? To which there are infinate and un-legislatable possibilities from earthquakes to avalanches and even, yes, acts of god ! As we drown in beaurocracy, its proliferation due to a neo-liberalist government similar to the neo-liberalists in the states and not coincidenatlly akin to the creationalists, we are forced to resign ourselves to the whims of the HSE.

The neo-liberalist state requires mountains of paper (read Hitch hikers guide to the galaxy) to verfiy via paperwork and countless "check" boxes that they are doing a great job. The more boxes you tick, the better you are doing. Even if the effects are totally intangeable.

This is the crux of the matter:

As less and less of us no longer believe in the virtues of God and no-one seems to have the intelligence and humanity to form morality based on just that, we now require little SS beaurocrats in white coats making up for the shortfall that is no longer under the control of God. By making sure nothing and absolutley nothing can possibly happen.
In the rare event that it does, you can expect millions in compensation becasue ultimatly there is an infinate number of "IFS" that could happen. Ironically. For us, alas, the last vestige of free will is the motor car. You have the capacity in a car to kill cyclists with scant punishment because the little people in white coats and clipboards are completely overwhelemd by the infinate possibilities that could go wrong whilst driving your car and can therefore not legislate against anybody causing death and harm by vehicular means. That means only one thing: Its Gods will - and so we go around both physically and theoretically in a circle.

Chip \'oyler

blu3cat wrote:

Right, you asked for it.

Here's a thread about Quantum Mechanics & metaphysics.

Picking up from what was going on in a RLJ thread (http://www.bikeradar.com/forums/viewtopic.php?t=12641153&postdays=0&postorder=asc&start=0) the collective physics borg of cyclists wil attempt to answer any questions about the nature of the universe.

In theory a thread to talk b*lls on.

So to start here's the very famous Schroedinger's cat (shortened)

Said cat sits in a sealed box, inside the box is a poison with exactly 50% chance of being released within 1 hour. So the question is without looking what state is the cat in after exactly 1 hour? Is it alive or dead? (no peeking inside the box).

And as a bonus: How do you know the sun will rise tomorrow.

I suspect the cat will either be sleeping or licking its arse

AyrshireBacon

There's an awful lot of views over Schroedinger's cat. The example above DOES NOT WORK!!!

The crux of the matter is that the poison is only released if a single radioactive atom decays within a period of it's half-life. A simple random number generator (50% on, 50% off) is not good enough. That only gives 50% dead / 50% alive (or 50% dead / 25% sleeping / 25% @rse licking).

The radioactive atom however can be considered (in a Quantum mechanics sense) to have both deacyed and not decayed. Hence the cat is both alive and dead at the same time. (I don't think cats can sleep and lick @rse at the same time so this is not even considered)

daviesee

Sealed box - cat dead due to suffocation.

The sun has never risen. The planet earth revolves. So it will not rise tomorrow.

Easy. Next.

jimjamyaharr

the cat can be thought of both dead or alive but it cant actually be both dead or alive

blu3cat

AyrshireBacon wrote:

There's an awful lot of views over Schroedinger's cat. The example above DOES NOT WORK!!!

The crux of the matter is that the poison is only released if a single radioactive atom decays within a period of it's half-life. A simple random number generator (50% on, 50% off) is not good enough. That only gives 50% dead / 50% alive (or 50% dead / 25% sleeping / 25% @rse licking).

The radioactive atom however can be considered (in a Quantum mechanics sense) to have both deacyed and not decayed. Hence the cat is both alive and dead at the same time. (I don't think cats can sleep and lick @rse at the same time so this is not even considered)

Yep I agree the example was simplified. And that a quantum process is necessary (although what happens if you use a macroscopic event trather than a quantum event?)

Oh and as for suffocation - make a big box with lots of air in.

the cat can be thought of both dead or alive but it cant actually be both dead or alive

It can be both dead and alive (and this is where quantum mechanics messes with your head). Experiments have shown that a single quanta of light fired at a target with 2 slots in it goes through both slits simultaneously. And as the cat being both dead or alive is controlled via a quantum process it is in theory both dead and alive, it's only when you look at it that it becomes one or the other.

Homer J

Give the cat a ball of string to play with and you have yourself a string theory, give it another one and you have multiple string theory. :?

dennisn

I seem to recall a theory wherein it is proven that you can never get anywhere.
To get from point A to point B you first must go halfway, then you must go half the remaining distance, and then half the remaining, and then...........and so so and so on.
Thereby, never arriving at point B because of having to go halfway, etc., etc.,

AyrshireBacon

blu3cat wrote:

Oh and as for suffocation - make a big box with lots of air in.

And you're not allowed to test the alive/dead state by shaking the box

jimjamyaharr

blu3cat
um so in theroy it can be dead or alive but in reallity it has to be one or the other, but only by observing the cat?

i have now put a cold, wet tea towel my head and retreated to a dark room.

my head hurts

AyrshireBacon

jimjamyaharr wrote:

blu3cat
um so in theroy it can be dead or alive but in reallity it has to be one or the other, but only by observing the cat?

i have now put a cold, wet tea towel my head and retreated to a dark room.

my head hurts

Actually it's not "dead or alive" but "dead AND alive". Both. At the same time you see.

Keep going with the tea towel & dark room, maybe start chanting "Ommmmm" to see if that helps as well.

ride_whenever

blu3cat wrote:

AyrshireBacon wrote:

There's an awful lot of views over Schroedinger's cat. The example above DOES NOT WORK!!!

The crux of the matter is that the poison is only released if a single radioactive atom decays within a period of it's half-life. A simple random number generator (50% on, 50% off) is not good enough. That only gives 50% dead / 50% alive (or 50% dead / 25% sleeping / 25% @rse licking).

The radioactive atom however can be considered (in a Quantum mechanics sense) to have both deacyed and not decayed. Hence the cat is both alive and dead at the same time. (I don't think cats can sleep and lick @rse at the same time so this is not even considered)

Yep I agree the example was simplified. And that a quantum process is necessary (although what happens if you use a macroscopic event trather than a quantum event?)

Oh and as for suffocation - make a big box with lots of air in.

the cat can be thought of both dead or alive but it cant actually be both dead or alive

It can be both dead and alive (and this is where quantum mechanics messes with your head). Experiments have shown that a single quanta of light fired at a target with 2 slots in it goes through both slits simultaneously. And as the cat being both dead or alive is controlled via a quantum process it is in theory both dead and alive, it's only when you look at it that it becomes one or the other.

You can exhibit the same phenomona with buckyballs that are cooled to the point of not emmitting any light. They then behave like wave/particles, even though they have a mass of around 720AU...

There is no reason that a macroscopic body cannot display quantum effects, it is just very unlikely due to the massive averaging effect of having a lot of particles.

jimjamyaharr

Ommmmm





Nah hasent helped :shock:

Stewie Griffin

Im going to be very upset if you have made an animal suffer for such a pointless experiment. Im sure this Schroedinger fellow might be a bit miffed too if its his cat you are using.

Surely what specific Poison it is will also have some bearing on its chances.

I have a question about the state of the Universe that needs answering. Why is it that more work I do to with a spreadsheet without saving it increases the chance that it will just fecking disappear just before Im about to print it off for a meeting?

jimjamyaharr

Arhh that would be sods law

blu3cat

AyrshireBacon wrote:

jimjamyaharr wrote:

blu3cat
um so in theroy it can be dead or alive but in reallity it has to be one or the other, but only by observing the cat?

i have now put a cold, wet tea towel my head and retreated to a dark room.

my head hurts

Actually it's not "dead or alive" but "dead AND alive". Both. At the same time you see.

Keep going with the tea towel & dark room, maybe start chanting "Ommmmm" to see if that helps as well.

yep both alive and dead at the same time.

Just imagine you have a snooker ball (just the one - any colour you like) and 2 pockets that feed into a retrieval tray.

There is exactly 50% chance of the ball going in either pocket (it will always go in one of them).

Simple so far, the ball will go through either one or the other pocket, right?

Now shrink the snooker balls and pockets down to a single photon, the smallest bit of light you can get, and the pockets to 2 slits, the ball reteival tray is now a light sensitive target.
You would think that the photon goes through either one or the other slit to get to the target at the other side. It does in fact go through both at once, and can be shown to do so.

see http://en.wikipedia.org/wiki/Double-slit_experiment read the quantum version of the experiment. Blew my head away first time I heard about it.

JackCB

Actually, experiments haven't shown 'that the photon goes through both slits at once'.

Experiments have shown that the specially prepared (mixed state) photon behaves differently after passing the slits to how you would expect a 'normal' (single state) photon, prepared so that it passed through either slit individually, to behave.

Whether you want to conclude from this that the photon 'passes through both slits' really depends on how you interpret Quantum Mechanics - and there's no consensus on 'the right way' to do this. Some people would say that the photon passes through one of the slits only, but that the way you've set up the experiment results in what can best be described as 'some weird shit' happening to it that affects the trajectory it follows. Others would say that asking which slit the electron passed through is meaningless. Or at least that the analogy you draw between the macroscopic snooker balls and the microscopic photons is a false one - snooker balls and photons are just too different things.

blu3cat

Actually, experiments haven't shown 'that the photon goes through both slits at once'

So how come you get the 2 slit interference pattern when only one photon is fired at a time?

I agree that the analogy is weak, but it's good to start out from familiar bits and move forward.

JackCB

Sorry, I was being a bit pedantic.

You're right the analogy is of value in that it shows something very weird is going on in a quantum mechanical world. And the experiments, of course, show that we do live in a world that obeys the laws of quantum mechanics.


The fact that you get the interference patterns and not the single dot pattern you would expect to see (classically) if you fired the photon through either slit does not necessarily show that the photon goes through both slits. It shows that there is some sort of quantum effect going on.

I guess my point is that although these effects are weird there is no general consensus on how to explain them because there is no general consensus on how quantum mechanics should be understood.

GraemeT

Just imagine you have a snooker ball (just the one - any colour you like) and 2 pockets that feed into a retrieval tray.

There is exactly 50% chance of the ball going in either pocket (it will always go in one of them).

You clearly haven't seen me play snooker :idea:

ride_whenever

and it happens with buckyballs too....

which are a nice analogy of a snookerball, assuming the paper i read wasn't disproved.

blu3cat

The fact that you get the interference patterns and not the single dot pattern you would expect to see (classically) if you fired the photon through either slit does not necessarily show that the photon goes through both slits. It shows that there is some sort of quantum effect going on.

I guess my point is that although these effects are weird there is no general consensus on how to explain them because there is no general consensus on how quantum mechanics should be understood.

yep point taken, although I like the 2 perpendiculr universes interfereing with each other theory.

and it happens with buckyballs too....

which are a nice analogy of a snookerball, assuming the paper i read wasn't disproved.

Aren't buckyballs geodesic balls of carbon atoms? how are they like snookerballs. (worth 7 points?)

Bugly

jimjamyaharr wrote:

the cat can be thought of both dead or alive but it cant actually be both dead or alive

Actually you are dead wrong - quantum physics in a sense demands that to be the case, the act of observation actually collapses the state vector; no observer then according to QM the cat is in a juxtaposed state. :shock:

This proposal has led some physicists to propose the branching universe type of theory to get around the living/dead or here/not here nature of QM

synchronicity

I find it hard to believe the initial assumption of EXACTLY 50% chance. 50.0000000000000000000000001% is not the same as 50%.

And by putting all this shite in a box, you've probably already affected the whole system through additional gravitational attraction between all the particles involved... i.e. if you can't even know the position of 3 freakin' atoms exactly w.r.t time (due to something called the n-body problem) how can you predict the probability of atomic decay with such precision?

The trouble is that it's all too easy to make wrong assumptions...