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Physics, Astronomy & Cosmology / Re: Are there any philosophical or other implications to the underlying randomness
« on: Yesterday at 22:56:42 »*solipsism.I can't believe you said that ;-)
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*solipsism.I can't believe you said that ;-)
I just reread what you quoted from me.It seems ambiguous now.When I said "to my mind" it was just to say "in my tentative opinion"So the decay of the nucleus is only of significance when it is measured (to my mind) and this "measurement" is a synonym with "interaction"A whiff of anthropocentrism here! The decay of a nucleus is of huge consequence to the nucleus itself, which ceases to exist or spawns daughters, even if there is no observer.
A lot of philosophical nonsense derives from the technical term "observer" that we use in science simply to denote a plane in spacetime through which information passes.
Thanks for your patience.Clearly I am poorly versed in Bell's theorem and also the localism vs realism question.As I hope I have understood Bell's theorem has clarified the random nature of physical interactionsDid it have much (anything?) to say about randomness? It seems that quantum theory in the first place (well before Bell came along) demonstrated the fundamental probabilistic nature of empirical things.
There were two principles held shortly after the turn of the 20th century: Realism and locality. The former says that things exist (a system is in a particular state) independent of measurement. The latter says that the effect cannot be separated from its cause in a space-like manner, or that cause-effect cannot move faster than light. Bell demonstrated that (barring superdeterminism), at least one of these principles must be false.Quotewe do only have interactions rather than isolated events don't we?I don't know what you mean by these things. An interaction is something that happens over time between different systems. An event (as usually used in physics) is a point in spacetime, but it also might be used to describe an occurrence, such as a particle interaction, say that shown by a Feynman diagram. In that sense, an interaction is a form of event. The decay of some nucleus is an event that isn't an interaction since there is but the one system.QuoteSo if the random event is something of a ground zero in our understanding of the physical world what else can we say about it aside from just accepting it and building on it?Again, I don't understand. Our understanding of the world isn't grounded on one event, or a group of them. There's a lot more to it.QuoteAre we still allowed to believe that randomness can still.be investigate to a deeper level of understanding or is this as far as things go?My apologies, but again, I don't know what's being asked. Measurements seem probabilistic by nature, but there are interpretations of QM that are not random at all, so the perceived randomness is hardly fundamental since it cannot be conclusively demonstrated.
So,is that to say that when we have just two.(or even one?) dots on the screen they can be graphically represented as an interference pattern even though our own optical system (the eyes and the brain) do not process it that way?Is there any other way we can reproduce that effect?I think I can give a tentative answer to your question, which is, it depends.
And what is "long enough"?
Two dots? Three?
In experiments that demonstrate interference, it's nice to see a pattern that we can say is definitely there.
But in quantum computers, the wavefunctions of two particles can be in superposition, such that it's a form of constructive or destructive interference.
We arrange for this to happen that way, and so it must have a nonzero probability of occuring in that case.
Last time I looked, I was definitely an old bloke, and AFAIK this Cambridge is cold, wet, and near the East Coast, just like the other one.Does the idea of a convention have import when discussing what "information" is?
You see, my friend, it all depends on what you think you mean by Cambridge. Is there a universal meme that can be deconstructed as a set of paradigms sufficiently delocalised in spacetime that your Cambridge and mine are the same but not identical, or identical but not, in whatever sense you think you are talking about, the same? In what sense does the Pythagorean essence of Cambridge heuristically or existentially conflict with the Aristotelian ur-Cambridge such that they cannot coexist?
I could say that in a few minutes I can walk across a bridge over the river Cam, but a philosopher would ask "how do you know that it is really you, and whilst the river was named by the Saxons, since the water that was there at the time is no longer there, is it still the Cam?
I'd say that depends on what the sentient being knows alreadyYes, I thought that too.The brain creates it's own inputs.Any external input goes through a huge amount of processing before anything like an output can be observed.
What a headacheOr what fun.
Hi.Ah yes,that has answered my question
@geordief asked about the speed c.
LaTex isn't working so we can't have mathematical symbols here in the post, sorry.
Basically, yes starting from the Lorentz transformation you would quickly obtain the relativistic velocity addition formula - see https://en.wikipedia.org/wiki/Velocity-addition_formula#Special_relativity
That will show you that a velocity with magnitude c (which is just what appears in the Lorentz transformation and not necessarily the speed of light) is mapped to another velocity with the same magnitude in any other inertial reference frame.
The entire discussion was about assuming light may not travel at the speed c. So, that's why @hamdani yusuf said what they said (I would think). In most textbook developments of special relativity it is common to start from an assumption about light and the invariance of its speed. In this situation, the whole point is that you don't - we assume light has some other speed.
You could still obtain the Lorentz transformation even if nature had been very unkind to physicists and never given them a massless particle that could be detected. We were lucky, we had light, it did exhibit properties that strongly pointed us to the development of special relativity. Assume light wasn't available or did not behave like that. Provided special relativity is still a rule in nature, then there would have been signposts to it.
See https://en.wikipedia.org/wiki/Experimental_testing_of_time_dilation which describes how muons can be produced in earths upper atmosphere when cosmic rays come in. We use this as a test of special relativity, specifically we suspect that muons moving fast relative to the lab frame would live long enough to reach the surface of the earth before decaying. The main point is that the effects of relativity like this would still be there, in nature, and eventually we would notice: Someone would have studied the half-life and decay of particles and they would have noticed that fast moving particles seem to live longer, they would have said "that's weird, it's as if their clock is ticking slowly". We now also have particle accelerators and with equipment like that to play with it's almost certain that we would have noticed strange effects when objects have high velocities relative to each other. Basically, unless the important speed which we are calling c and appears in the Lorentz transformation was many orders of magnitude greater than it actually is, then there would have been signposts to relativity and eventually we would have noticed them.
With some LaTex mathematical symbols (which, as I mentioned, we don't have the luxury of), we could demonstrate that the Poincare group of transformations is the only set of transformations between reference frames we should consider. Non-linear transformations are also possible but the words "non-linear" should strike fear into the hearts of anyone who has ever studied some mathematics. So you can rest assured that every linear transformation between reference frames would have been proposed and examined first. The basic Poincare transformations like a rotation of the space frame won't explain the results you were getting from experiments so before too long the subset of the Poincare transformations which are just the Lorentz boosts would be all you have left before you move to non-linear transformations. While mathematicians would be beginning to sweat and fear that non-linear transformations would be needed, the last set of linear transformations would turn out to be the charm, they would work. Obviously a Lorentz boost will work, we know that a Lorentz transformation was precisely what we needed. There would be a constant which we can call c in those transformations, it would have the dimensions of a speed etc. The value of c would be chosen to match the experimental results we were obtaining. Once you have the Lorentz transformations, the rest of the theory of special relativity follows.
So, summarising all of that, we could reasonably have obtained the Lorentz transformations just from empirical observations of strange effects when two objects have high velocities relative to each other. Having a massless particle like light which did travel at c was a great help and it is a clear signpost to relativity. It probably speeded up the recognition and development of relativity by many years. Indeed taking, as an axiom, that the speed of light is an invariant will allow you (a lecturer) to develop the theory of relativity on the blackboard in front your students in 1 hour rather than over several lectures. The key is that it wasn't essential, special relativity is just all the physics which you can obtain from the Lorentz transformation. You can get to that (the Lorentz transformation) by other routes, you do not need to assume the speed of light is an invariant. (However, in the world in which we do live, the speed of light is c, so you aren't doing any harm by taking that as an axiom and you will see it done in many textbooks and hear it suggested by many people. You need this much space on a forum to explain why it isn't quite like that).
I hope that helps.
Best Wishes.
That was not what I was asking -unless your implication is that the invariant speed c ,(contrary to what @Janus said) is completely linked to the speed of light in a vacuum .Can I ask you what are some of the derivations that show that c is an invariant speed and which have no connection to the speed of light?In Special Theory of Relativity, invariance speed of light is taken as a postulate, hence not derived from some more fundamental axioms.
The key here is that it is "c" which is the important thing, not the light itself. As far as we know, light in a vacuum travels at c. But even if this turned out not to be the case, it would not change the importance of the speed c as an invariant speed. It would just mean that the photon is not the truly "massless" particle we now consider it to be.Can I ask you what are some of the derivations that show that c is an invariant speed and which have no connection to the speed of light?
So collapsing the wave function is a bit like swatting a fly ?Measurement of one property will cause a wave function collapse and the wave function is then changed.I seriously disparage this statement!
You can plot the outcome of dice throws as a wave function. You throw the dice and get a number. You haven't done anything to the hypothetical wave function, just chosen one value of it, which you could not predict. If you roll the dice again, you will get an equally unpredictable number. If you had "collapsed" the wave function, you would have restricted the range of future possibilities - the gambler's fallacy.
It is perfectly true that if you measure any property of a subatomic particle you will have altered its state in some way, e.g. by bouncing a photon off it, and thus biased its future state and wave function because you have changed its energy and momentum, but the notion of "collapse" rather militates against Heisenberg.
decay of an atom?
Are you happy with the answers / discussion so fa
So, if you have anything nearby that you want to measure the length of, your clock is wrong and so is your rulerWhy is that important.?We can never attain absolute accuracy in measurements ,can we?
Apart from anything else, how do you measure time?Is a time unit arrived at by counting the spontaneous and random emissions in the radioactive decay of an atom?
I will defer to others here to answer that .....As it transitions between mediums?When a photon is ejected from an electron going to a lower energy level, what acceleration does the photon have?From what I have read a photon (in a vacuum) does not accelerate and only moves at the one speed(c)
When a photon is ejected from an electron going to a lower energy level, what acceleration does the photon have?From what I have read a photon (in a vacuum) does not accelerate and only moves at the one speed(c)