Ask a physicist anything. (2)

[chilehed]

Not if it is dead.

When state reduction actually occurs (or if it does) is an/the issue.

To hopefully confuse you more. Is the original observer actually an observer? Is the cat dead or alive until it is observed or is it dead or alive until the observer of the cat is observed?

Seems to me that since the cat's alive at the start of the process, it's its own observer. Paradox solved.

 

[Wiccan_Child]

The Casimir effect was predicted before it was observed. It cannot be uncaused because then it would not have been predicted.

I disagree. An uncaused event can occur in such number and in such particular conditions that it can be exploited. A sea of virtual particles popping into and out of existence, predicted to occur by a quantum mechanical understanding of vacuum energy, and predicted to be uncaused, can be experimentally falsified.

I believe you know why it happens and why you can't say that is uncaused.

Indeed: because I never said it was uncaused.

The rest I'll leave for the moment because I don't want to get into the same conversation on wave collapse as the last time.

Did we have this conversation before? You sure you're not from another universe where we did?

If an event can cause anything then causality is not upended.

It can if spontaneity exists. Hard determinism precludes any chance or random events from occurring. Causality is more than just 'an event has a cause'.

 

[Wiccan_Child]

So you watching the game right now ?
28-28 in Overtime right now NO has the ball

Twenty-eight and twenty-eight,
N.O. has the ball,
They're in Overtime right now.

Gotta love haiku.

 

[Maxwell511]

I disagree. An uncaused event can occur in such number and in such particular conditions that it can be exploited. A sea of virtual particles popping into and out of existence, predicted to occur by a quantum mechanical understanding of vacuum energy, and predicted to be uncaused, can be experimentally falsified.


Indeed: because I never said it was uncaused.

It can if spontaneity exists. Hard determinism precludes any chance or random events from occurring. Causality is more than just 'an event has a cause'.

I think we are using two distinct definitions of "cause".

I looked at the dictionary definition of "cause" and I think we are both right. Cause: The producer of an effect, result, or consequence. The definition of the "cause" I was using was the narrow; The producer of an effect. I think you are using the narrow; The producer of a consequence.

Did we have this conversation before? You sure you're not from another universe where we did?

I think so...but then again I do sometimes make stuff up in my head.

It was a year or two ago in some thread where the OP suggested consciousness creates reality because it causes wave collapse. You took a very strict Copenhagen Intrepretation for why they were wrong and I took a Many Worlds view of why they were wrong, we both took postions that each other was wrong. Fun times. At least that is how I remember it. I'll try and find the thread.

 

[Dr Doofenshmirtz]

I said-

I could be wrong, but the Cat thought experiment does not postulate that the cat exists in "two or more places at once".
The point of it is that the decay cannot be nailed down to a single definable moment, but merely relies on a probability of the element decaying at any given moment.

You replied (without explanation)-

You are wrong.

I would appreciate an explanation, TYVM.
"you are wrong" is no more an explanation than AV's "God did it".


If you are incapable (or unwilling) of giving it, then perhaps Wiccan Child or Cabal are able to do so.

Specifically, I'd like to know (from you, WC or Cabal) how the cat thought experiment states that the cat is in more than one physical location at the same time.

Or perhaps you (or others) can explain how Schrödinger's cat does not (since I'm "wrong") explain , through the thought experiment, how the current probability of a given decay is merely a probability until directly observed (yeah, that's a crude way of putting it, but it's late here for me).

 

[Maxwell511]

Sorry for not giving a full explanation. You are wrong in thinking..

The point of it is that the decay cannot be nailed down to a single definable moment, but merely relies on a probability of the element decaying at any given moment.

That is not the point of the thought experiment. The point is that the system's state is not determined until state reduction occurs.

It does relate to things being in two place at once also for example:

Imagine that I was meant to me you at a cafe for coffee. The reasoning behind the Cat experiment is that I also have a wave function associated with me. This wave function evolves so that there is a probability that I am waiting at the cafe for you or that I am late and somewhere else. With QM reasoning until you arrive at the cafe (open the box in the Cat experiment) I am both late and I am at the cafe, it is your arrival that decides where I am. Does that make sense?

 

[Dr Doofenshmirtz]

Sorry for not giving a full explanation.

Thankee

That is not the point of the thought experiment. The point is that the system's state is not determined until state reduction occurs.

When the wave form collapses to a single event, correct?
Of course, as I understand it, the wave form truly only applies to subatomic particles.
If I'm wrong, please explain

It does relate to things being in two place at once also for example:
Imagine that I was meant to me you at a cafe for coffee. The reasoning behind the Cat experiment is that I also have a wave function associated with me. This wave function evolves so that there is a probability that I am waiting at the cafe for you or that I am late and somewhere else. With QM reasoning until you arrive at the cafe (open the box in the Cat experiment) I am both late and I am at the cafe, it is your arrival that decides where I am. Does that make sense?

Or your arrival.
I always understood the Cat experiment to apply to the apparently random but probabilistic chance or radioactive decay, not whether the cat is actually dead or whether you arrive or not.


Now, granted, massive objects (by that I mean "big") such as you, golf balls and the grain of sand on a beach DO have a wave function, but they are so small (as I understand it) as to be probabilistically near 0.

For example, try to run through a solid concrete wall. There IS a chance is could happen, but according to what I have read, it would take longer than the age of the universe to do so.

Quite unlike electrons which do the same thing "all the time" (so to speak)

 

[RealityCheck]

The Cat problem originally wasn't about being in two locations at once, but the cat being in two states at once - namely, both alive and dead.

The idea is that the decay of any single atom in the radioactive substance is random - there is no way to concretely determine when a single atom will decay. You can only determine that over X period of time, there is a high probability that 1/2 will have decayed, or that 1/4 will have decayed, etc.

Schrodinger's idea was that the death ray or gun or whatever would be triggered by a specific, small amount of radioactive substance decaying. Once exactly X number of atoms had decayed, the gun would fire and kill the cat instantly. But the math said there was no way to know precisely when this would occur. The math ALSO showed that at any given time, the system was actually in both states - that is, there was both enough to trigger the gun and not enough to trigger the gun. The cat being part of the system, that implied that the cat, at any time, was both dead and alive at the same time. The wave function had not collapsed to a single solution at that time - until the scientist opens the box and observes the cat.

His point was that his own equations had some rather silly and strange implications - not that he believed that meant he was wrong (because he clearly wasn't) but that it seemed his work led to some disturbing philosophical implications - not just being dead and alive, but also, that the mere act of observation would force a system into a single solution.

Of course, Schrodinger never considered that the cat itself is an observer, and its own acts of observation force the system to collapse into a single solution at all times. So the paradox is actually moot.

 

[Maxwell511]

When the wave form collapses to a single event, correct?
Of course, as I understand it, the wave form truly only applies to subatomic particles.
If I'm wrong, please explain

If the wave model is correct then it applies to us as well. The wave function exists for multiply particle systems and we are comprised of multiple particles. For example within atoms there is no real distinct electrons, there is a wave function but no separate particles.

Or your arrival.
I always understood the Cat experiment to apply to the apparently random but probabilistic chance or radioactive decay, not whether the cat is actually dead or whether you arrive or not.

"My" arrival would require state reduction, if I am part of the system and not an observer of the system then state reduction would not occur. Schrodinger devised the experiment to show how deduction from the quantum to the classic produces absurdities. He was basically saying that QM was accurate but could not be "right".

Now, granted, massive objects (by that I mean "big") such as you, golf balls and the grain of sand on a beach DO have a wave function, but they are so small (as I understand it) as to be probabilistically near 0.

For example, try to run through a solid concrete wall. There IS a chance is could happen, but according to what I have read, it would take longer than the age of the universe to do so.

Quite unlike electrons which do the same thing "all the time" (so to speak)

My thought experiment with the cafe is terrible compared to the originals. The Cat experiment is purposely designed so that the system is in a critical state (so that a slight perturbation can cause massive effects.) Maybe we can run through walls in the future if we design the system correctly.

 

[Dr Doofenshmirtz]

If the wave model is correct then it applies to us as well.

I agree with that, considering what I said above.

The wave function exists for multiply particle systems and we are comprised of multiple particles. For example within atoms there is no real distinct electrons, there is a wave function but no separate particles.

I do understand that electrons do not exist except in certain "probabilities"
But I thought that the Schrodinger Wave Function applied more to individual subatomic particles.

"My" arrival would require state reduction, if I am part of the system and not an observer of the system then state reduction would not occur.

But you cannot be "not an observer"

Schrodinger devised the experiment to show how deduction from the quantum to the classic produces absurdities.

Well of course
I get that
QM is not "intuitive" (so to speak)

He was basically saying that QM was accurate but could not be "right".

"right"?
Can you qualify that statement?
Potential paradox, yes, but not "right"?
I R confused now.

My thought experiment with the cafe is terrible compared to the originals. The Cat experiment is purposely designed so that the system is in a critical state (so that a slight perturbation can cause massive effects.) Maybe we can run through walls in the future if we design the system correctly.

The Cat experiment is designed to demonstrate that, although we can predict a PROBABILITY of decay (in this specific instance), we cannot predict exactly WHEN that decay will occur.
Therefore, without an observer, we will never know if the Cat is dead until we open the box.
Anything beyond that may be metaphysics.

It is NOT designed to demonstrate being in two physical locations at the same time. It's all about the uncertainty of the precise moment of the decay rate (minus the possible metaphysics)



Question for you- Do you subscribe to the "Many Worlds" hypothesis? (yes, this is, from my pov, important)


BTW, really looking forward to WC's input and Cabal's input as well. (no offense Max )

 

[Assyrian]

What happens if you lock Schrodinger in the basement when he does his experiment? Always a good precaution with PETA around. 7am he opens the box and the cat wave function collapses. But it isn't until 9am when you open the basement that you know you have Schrodinger hugging his dead cat, or the tattered remains of a renowned physicist and a very angry ball of fur. When does the cat wave function collapse? Or is it both collapsed and not collapsed until we observe Schrodinger and the cat?

 

[Wiccan_Child]

I think we are using two distinct definitions of "cause".

I looked at the dictionary definition of "cause" and I think we are both right. Cause: The producer of an effect, result, or consequence. The definition of the "cause" I was using was the narrow; The producer of an effect. I think you are using the narrow; The producer of a consequence.

If I had a pound for every time a disagreement has boiled down to semantics .

I think so...but then again I do sometimes make stuff up in my head.

It was a year or two ago in some thread where the OP suggested consciousness creates reality because it causes wave collapse. You took a very strict Copenhagen Intrepretation for why they were wrong and I took a Many Worlds view of why they were wrong, we both took postions that each other was wrong. Fun times. At least that is how I remember it. I'll try and find the thread.

So long as we both agreed that he was wrong, I'm happy!

 

[Wiccan_Child]

Specifically, I'd like to know (from you, WC or Cabal) how the cat thought experiment states that the cat is in more than one physical location at the same time.

It doesn't. It states that the cat is in more than one state at the same time (in this case, the cat can be in either the 'alive' state or the 'dead' state, and quantum mechanics says that it is in both).

Of course, as I understand it, the wave form truly only applies to subatomic particles.
If I'm wrong, please explain

Only subatomic particles exist. What is a cat but an ensemble of particles, each with their own wavefunction?

I always understood the Cat experiment to apply to the apparently random but probabilistic chance or radioactive decay, not whether the cat is actually dead or whether you arrive or not.

Nope, that's just the way quantum mechanics is introduced into the system. The experiment is designed to show how the cat can be both dead and alive, not that the moment of decay is fundamentally unpredictable.

Now, granted, massive objects (by that I mean "big") such as you, golf balls and the grain of sand on a beach DO have a wave function, but they are so small (as I understand it) as to be probabilistically near 0.

I think you mean '1'. They have to exist somewhere, after all .

For example, try to run through a solid concrete wall. There IS a chance is could happen, but according to what I have read, it would take longer than the age of the universe to do so.

Bingo.

Quite unlike electrons which do the same thing "all the time" (so to speak)

Well, they have a better chance, but I doubt more than a couple manage to do it a year.

On the other hand, scanning tunnelling microscopy works on the principle that electrons can tunnel out from a material.

 

[Wiccan_Child]

What happens if you lock Schrodinger in the basement when he does his experiment? Always a good precaution with PETA around. 7am he opens the box and the cat wave function collapses. But it isn't until 9am when you open the basement that you know you have Schrodinger hugging his dead cat, or the tattered remains of a renowned physicist and a very angry ball of fur. When does the cat wave function collapse? Or is it both collapsed and not collapsed until we observe Schrodinger and the cat?

The cat's wavefunction collapses when Schrödinger looks inside the box. But the entire basement's wavefunction doesn't collapse till the police come knocking at his door. It's all a bit squiffy.

 

[stella_ku]

how did the universe become to be / who or how was it created???
- serious question

 

[Wiccan_Child]

how did the universe become to be / who or how was it created???
- serious question

We have no idea. My pet hypothesis is that the universe came into being because there was nothing stopping it, so to speak.

What we do know is that the universe has been expanding for 13.5 billion years from a small, hot, dense state to its current state; this process is called the Big Bang. What happened before then is anyone's guess.

 

[Assyrian]

It doesn't. It states that the cat is in more than one state at the same time (in this case, the cat can be in either the 'alive' state or the 'dead' state, and quantum mechanics says that it is in both).

We need to design an experiment where the cat wave function goes through two cat flaps. If you ran the experiment a few times would the dead cats form an interference pattern on the wall?

 

[RealityCheck]

how did the universe become to be / who or how was it created???
- serious question

Wiccan started off with a good general answer.

In the days when Big Bang theory was first being put forth, there were other scientists who held to an alternate theory, the Steady State theory. Steady State is kind of rooted in old Greek philosophical ideas, that the universe had always been, would always be, and had neither beginning nor end - not spatially or in time. It was the work of Hubble, amongst others, that provided the observed evidence that Steady State was wrong - the expansion of the universe, for example, could be accounted for by Big Bang (and in fact was predicted by that theory as a consequence), but Steady State had no answer for it. There were attempts to reconcile it with evidence, but it didn't take long for it to be abandoned and BB accepted as correct.

So given that - what happened at the Big Bang? That's still something being worked out. We know a great deal now about what happened in the early universe not long after it began - say, after the first three minutes of its existence (at which point most or all of the physical laws that govern our universe today also governed that early universe). Beyond a certain time, however, we can't yet really discover much. There is a certain time in the early universe before the first atoms formed. Atoms are mostly empty space, and the space around them is mostly empty space even with other atoms around. So it's fairly easy to see "through" such points in space-time. But prior to atoms forming, there's far less empty space - physical laws that allow for atoms now were not in operation, so it was possible for space to be far less empty - you could pack particles into a much denser space. In essence that makes a kind of barrier in our vision - we literally can't see past a certain point in space-time because it's just not physically possible to. (Yet, anyway)

Before that, it's likely there was no such thing as matter - matter had not formed yet. Energy was all there was - and that energy then became the energy that formed into matter (as General Relativity holds it does). That energy was bound up in a tiny, tiny bit of space-time that then expanded, rapidly, and continues to expand today as our universe, our space-time.

Just as matter and energy are bound together, one able to become the other, so are space and time. Space and time do not exist separately from each other in our universe. So, if the universe was, at some point, bound up into an infinitesimally small space, a space the size of zero, then time also was at zero - with zero space, there is zero time. Once space began to expand, so did time.

Essentially that means it's nonsense in science to ask "what happened before the big bang" because there was nothing that COULD happen before the big bang. Time, as we understand and experience it in this universe, did not exist. (Language gets confusing here because we cannot help but say things like "time didn't exist back then." Back then? That implies time! How can time exist within time? It can't, and that's just a fault of our language - but not of physics.)

If there were any space other than our universe, it is outside our universe and not bound by the laws of physics of this universe. If there were any time other than our universe, it's not part of the time we experience in our universe. So yes, there COULD be a "before" the big bang, but that before is necessarily a completely different "time" than the time of our universe, and not connected in any way.

Now, whatever caused the big bang to happen is also necessarily outside the realm of our universe's physics. If something could 'cause' the 'effect' of the big bang, but time of our universe did not exist except as an effect of that cause, then that 'cause and effect' had to be a chain of events that occured in a different space-time - an extra-dimension, maybe. But it cannot be considered a cause and effect within our own sense of time.

That generally means that whatever it was that *caused the Big Bang is something outside our current understanding of physics and science in general. That doesn't mean we can't possibly know or develop theories about it... it just means it's much harder to get any evidence of it.

Could it be a 'who' instead of a 'what'? Sure. But such a 'who' is equivalent to a 'what' because it's just as incomprehensible, being outside the realm of physical understanding.

 

[Doveaman]

Wiccan started off with a good general answer.

In the days when Big Bang theory was first being put forth, there were other scientists who held to an alternate theory, the Steady State theory. Steady State is kind of rooted in old Greek philosophical ideas, that the universe had always been, would always be, and had neither beginning nor end - not spatially or in time. It was the work of Hubble, amongst others, that provided the observed evidence that Steady State was wrong - the expansion of the universe, for example, could be accounted for by Big Bang (and in fact was predicted by that theory as a consequence), but Steady State had no answer for it. There were attempts to reconcile it with evidence, but it didn't take long for it to be abandoned and BB accepted as correct.

So given that - what happened at the Big Bang? That's still something being worked out. We know a great deal now about what happened in the early universe not long after it began - say, after the first three minutes of its existence (at which point most or all of the physical laws that govern our universe today also governed that early universe). Beyond a certain time, however, we can't yet really discover much. There is a certain time in the early universe before the first atoms formed. Atoms are mostly empty space, and the space around them is mostly empty space even with other atoms around. So it's fairly easy to see "through" such points in space-time. But prior to atoms forming, there's far less empty space - physical laws that allow for atoms now were not in operation, so it was possible for space to be far less empty - you could pack particles into a much denser space. In essence that makes a kind of barrier in our vision - we literally can't see past a certain point in space-time because it's just not physically possible to. (Yet, anyway)

Before that, it's likely there was no such thing as matter - matter had not formed yet. Energy was all there was - and that energy then became the energy that formed into matter (as General Relativity holds it does). That energy was bound up in a tiny, tiny bit of space-time that then expanded, rapidly, and continues to expand today as our universe, our space-time.

Just as matter and energy are bound together, one able to become the other, so are space and time. Space and time do not exist separately from each other in our universe. So, if the universe was, at some point, bound up into an infinitesimally small space, a space the size of zero, then time also was at zero - with zero space, there is zero time. Once space began to expand, so did time.

Essentially that means it's nonsense in science to ask "what happened before the big bang" because there was nothing that COULD happen before the big bang. Time, as we understand and experience it in this universe, did not exist. (Language gets confusing here because we cannot help but say things like "time didn't exist back then." Back then? That implies time! How can time exist within time? It can't, and that's just a fault of our language - but not of physics.)

If there were any space other than our universe, it is outside our universe and not bound by the laws of physics of this universe. If there were any time other than our universe, it's not part of the time we experience in our universe. So yes, there COULD be a "before" the big bang, but that before is necessarily a completely different "time" than the time of our universe, and not connected in any way.

Now, whatever caused the big bang to happen is also necessarily outside the realm of our universe's physics. If something could 'cause' the 'effect' of the big bang, but time of our universe did not exist except as an effect of that cause, then that 'cause and effect' had to be a chain of events that occured in a different space-time - an extra-dimension, maybe. But it cannot be considered a cause and effect within our own sense of time.

That generally means that whatever it was that *caused the Big Bang is something outside our current understanding of physics and science in general. That doesn't mean we can't possibly know or develop theories about it... it just means it's much harder to get any evidence of it.

Could it be a 'who' instead of a 'what'? Sure. But such a 'who' is equivalent to a 'what' because it's just as incomprehensible, being outside the realm of physical understanding.

So as to clear up the confusion, God did it.

 

[sandwiches]

So as to clear up the confusion, God did it.

So as to clear up the confusion, here's a translation:
"God did it" = "We don't know."

You can use them interchangeably as they provide just as much information and are equally helpful in furthering our understanding of our universe.