Big Bang Found

Dr. A writes: Well, it's one thing to say that the cause of the fluorescence is the UV light. It's much more tendentious to point to a particular electron and say "The cause of the fall to its ground state was being hit by a high-energy photon".

Agreed. It would be more normal to say that the electron fell to its ground state because it was in an excited state, a lower energy state was available, and this transition was energetically favorable.

Dr. A writes: Suppose someone says: "John's death was caused by his interest in botany". How do you make that out? we ask. "Well, he'd never have been at the top of that cliff if he hadn't wanted to see the rare Clifftop Saxifrage". Well, this may indeed have been a necessary and sufficient condition to get him to the top of the cliff, but surely the cause of his death was whatever got him to the bottom.

Yes, there is always a causal chain of events. Depending on the situation and the question, we may speak of causation at different levels of the chain.

If, as some claim, the instability of a vacuum (i.e. nothing) produces a probability that a universe will emerge, then you have your cause.

A cause for one element of existence to arise from another - hardly profound nor really what kb is talking about.

This is why claiming that nuclear decay is "uncaused" and therefore we have an example of how the Universe can come into being "uncaused" is completely bogus.

The problem is that you have not established what causes an alpha particle to leave when it leaves and what causes it to stay when it stays. Yes, quantum mechanics does predict exactly that behavior, but QM does not explain or point to an impetus for the alpha particle to escape. As best we know, there is no such impetus.

"as best we know" - good words

Nuclear emission of an alpha particle is such a macroscopic event - the complexity of the state of all the underlying interacting particles (fields) involved here is staggering. The nuclear decay probability is not some simple random distribution, but the aggregate of an unfathomable number of interactions. The state space of a nucleus is enormous and it is continuously moving through that space. Some areas of that state space may lead to some decay mode. Our inability to probe that state space leads us to say "random" and "stochastic" but it does not give us the right to declare "uncaused" in some ontological sense.

ringo writes: The laws of nature don't have to "come from" anywhere. They just are. They're properties of nature, just like wind conditions and snow conditions. Anything that exists will have properties whether anybody/anything "puts" them there or not.

Perhaps instead of a Creator, we have an eternal observer. Perhaps this observer effect influences the idea that reality is not so much caused as it just is.

Phat writes: Perhaps instead of a Creator, we have an eternal observer.

Perhaps there's an eternal straw for us to clutch at.

I would think NoNukes' point still stands though, in that I could take a hydrogen atom in an excited state, which at some point transitions to the ground state. In standard Quantum Mechanics this transition is uncaused. Similarly with the tunneling of an alpha particle out of a nucleus, reagrdless of how complicated the interactions are, they are still only a complicated development of a wavefunction which only gives a probability. There is no cause of the actual emission.

Of course one could say that the standard picture of quantum mechanics is wrong and that there is an underlying theory where these things are caused, but I think results like Gleeson's theorem, the Kochen-Specker theorem, the infinite baggage theorem, e.t.c. show that such an underlying theory will have some pretty bizarre properties that seem just as hard to swallow as quantum mechanics indeterminate nature.

In the current scientific theory of the strong interactions (QCD), I think Nonukes' statement is correct. Alpha emission is uncaused.

frako writes: What is the cause that creates the 2 opposite virtual particles, we know why they vanish from existence because they collide.

Your question is not very clear.  Can you please better describe the situation that you are referring to?  

I'm not an expert on virtual particles or Feynman diagrams. Some of the folks here probably are much more familiar with them than I. So I'll just make some general comments on virtual particles.

First, as Prof Strassler explains, virtual particles are just that--virtual, not real.  They are primarily a conceptual, computational tool.  Do conceptual entities which do not really exist need a cause?  I dont think so.

Second, these virtual particles are equivalent to fluctuations in the vacuum energy which fills all space.  What causes these fluctuations?  As Prof Strassler says:

Prof. Strassler writes: A "virtual particle", generally, is a disturbance in a field that will never be found on its own, but instead is something that is caused by the presence of other particles, often of other fields.

Indeed, for the most commonly cited observable effects of virtual particles, we can point to external influences as their cause.  For example,

Wikipedia writes: The Casimir effect, where the ground state of the quantized electromagnetic field causes attraction between a pair of electrically neutral metal plates.

(i.e. the arrangement of the plates sets boundary conditions for the quantized field, causing only certain modes to be allowed)

Wikipedia writes: Hawking radiation, where the gravitational field is so strong that it causes the spontaneous production of photon pairs (with black body energy distribution) and even of particle pairs.

And vacuum polarization, which is caused by a strong external electric field.

Can any of you think of any observable effects of virtual particles where we cannot point to external influences as the cause?

 
 

Edited by kbertsche, : No reason given.

The nuclear decay probability is not some simple random distribution, but the aggregate of an unfathomable number of interactions. The state space of a nucleus is enormous and it is continuously moving through that space.

I cannot rule that out, of course, but what you are saying does not appear to be kbertsche's argument. He does not seem to think nuclei have an "aged" state either, or at least he takes no issue with my saying so.

Our inability to probe that state space leads us to say "random" and "stochastic"

Do you believe that probing the state would turn up a mechanism? Because if not, then saying decay occurs "stochastic" after a nuclei is formed is just description and not an argument that decay has a cause (or that it does not).

And of course, nothing, even including an impossible probing, can really prove that something is "uncaused in an ontological sense", if omnipotence and science defying power are allowed. Perhaps the Creator watches individually over atomic nuclei and triggers their fate on a schedule that produces the half lives we observe.

in that I could take a hydrogen atom in an excited state, which at some point transitions to the ground state. In standard Quantum Mechanics this transition is uncaused.

Of course, if you *model* the situation in the usual way with QM. But you are setting up an oversimplification of the what is actually occurring. I'm not claiming that QM is deterministic, but we are looking at higher level processes.

similarly with the tunneling of an alpha particle out of a nucleus, reagrdless of how complicated the interactions are, they are still only a complicated development of a wavefunction which only gives a probability.

Yes, but this *single* wavefunction is a coarse-graining of what is going on within the nucleus. To simply describe the emission of the alpha particle as uncaused suggests some random-number-generator associated with a solid-ball nucleus, rather than the nucleus as a complex composite quantum entity, and the alpha emission as a complex quantum process. As you well know, the half-life isn't some god-inspired parameter casually associated with a particular nucleus.

In the current scientific theory of the strong interactions (QCD), I think Nonukes' statement is correct. Alpha emission is uncaused.

As far as I am aware we only have an excessively idealised and over-simplified QCD description of alpha emission, so this is not exactly surprising.

My concern with this kind of language, attributing the acausal behaviour to high-level QM phenomena (H-atom transition, alpha-emission), is it suggests that there is no further underlying mechanism to investigate (E-W and QCD)

But more to the point, while the probabilistic nature of QM may very well have something to do with the "trivial" idea of our Universe coming into being from some pre-existing state, it has nothing to do with the theists' (and KB's) ideas of "creation" of existence itself - "something from nothing" - and talking about uncaused quantum events within our Universe is decidedly unhelpful, not to mention a great example of the fallacy of composition.

I cannot rule that out, of course, but what you are saying does not appear to be kbertsche's argument.

It's not - I was merely getting a bit upset at what I was seeing as a "trivialising" of the incredible process of nuclear decay

And more importantly, the utter irrelevance of quantum processes to the question of what "caused" the Big Bang if there was no "before". KB made the cardinal sin of talking about existence "beginning" to exist, and he wanted a cause for this. Rather than talking about uncaused events, he should have just been dissuaded of this notion as it is only there to provide a "gap" for a theistic intervention.

Do you believe that probing the state would turn up a mechanism?... ...Perhaps the Creator watches individually over atomic nuclei and triggers their fate on a schedule that produces the half lives we observe.

As I tried to explain in my reply to SG, yes there is a more fundamental mechanism (nuclear QCD) and that is where the half-life is determined, but I'm not trying to discount the uncaused nature per-se, just that it occurs at a deeper level.

Edited by cavediver, : No reason given.

and talking about uncaused quantum events within our Universe is decidedly unhelpful, not to mention a great example of the fallacy of composition.

I have to take issue with the accusation of indulging in a fallacy. Talking about quantum events in the universe came up in reaction to arguments that causation was our total experience and therefore must be applicable to the universe. The idea was to cause k-man to re-think some of his arguments and not to win the entire argument by analogy or multiplication/addition.

Ultimately thought I could not accomplish my objective. At least we were noisy enough to get a couple of physicists to comment. I consider that a win.

Edited by NoNukes, : No reason given.

First, as Prof Strassler explains, virtual particles are just that--virtual, not real. They are primarily a conceptual, computational tool. Do conceptual entities which do not really exist need a cause? I dont think so.

Um we can measure their effects so they are real they just exist for such a short time we call them virtual.

Can any of you think of any observable effects of virtual particles where we cannot point to external influences as the cause?

The Casimir Effect

frako writes: kbertsche writes: Can any of you think of any observable effects of virtual particles where we cannot point to external influences as the cause? The Casimir Effect

No, I specifically mentioned the Casimir effect as caused by external influences. It is caused by the quantization of the wave function and the fact that an external apparatus has been set up to provide boundary conditions which eliminate many of the potential modes. (Your video explains how the plates do this). Without such external influences to set boundary conditions the effect won't exist.

Edited by kbertsche, : No reason given.

NoNukes writes: At least we were noisy enough to get a couple of physicists to comment. I consider that a win.

Perhaps you mean cosmologists or particle physicists, not just physicists?
As long as I've been participating in this discussion you've had a physicist commenting.

Without such external influences to set boundary conditions the effect won't exist.

I believe that your original question is carefully worded not to produce a relevant answer. Because even if what you say is correct, the question of whether virtual particles are real rather than just math does not rely on whether an apparatus is required to detect them.

Is the Casimir merely effect the attraction between the two metal plates generated in the absence of external fields? Then obviously the effect depends on the apparatus, and in particular having the metal plates.

If the question being answered is whether virtual particles exist, then the fact that those conditions are required to produce the Casimir force does not demonstrate that there are no virtual particles.

In a sense, your position is like insisting that there is no electrostatic field present in a room absent another particle or a time varying magnetic field to produce a detectable effect.