This is an aside folks but I sent the message below to one of the moderators, 'Baden,' 22 hours ago as a PM. I am probably being too impatient here but he has not got back to me yet and I just noticed that my @EugeneW above did not work, it did not appear as I thought it would. I thought the @member handle resulted in that member being informed of the mention. Perhaps one of you reading this thread could answer my questions below faster than 'Baden' seems able to.

Hi,
Could you answer a few quick questions for me. How do you refer/mention another member in a post?
I have seen the @member handle, reference used by other members. But I just tried @Garret Travers and it did not appear as a link.
Oh, I've just realised, his handle is Garrett Travers (two t's in his first name), is that the reason it didn't work?

A couple of other questions.
Is there no way to change the size of text in a post?
Can you insert a direct link within a current post, to a previous post earlier in the same thread or to an earlier post you have made in another thread? If so, how do you do this?

Waveforms certainly exist in electronics, — jgill

Are you referring to traveling analogue waves as data packets are transmitted through the air using from source (DAC (Digital to analogue converter)) to destination ADC (analogue to digital converter)?
or digital waveforms (Castle turret shaped)?

Based on the wikipedia entry I pasted on my most recent response above, to noAxioms, I think the waveforms of computing would be described as belonging to the 'classical' category and differ from that produced by a 'wavefunction' in quantum physics.

As a maths expert, do you have anything to add that would aid my understanding of the difference between the terms wave /function/form/equation as they are used in maths compared to quantum physics?

Especially you... Tedious indeed... :fire: — EugeneW

Well said! :clap: :wink:

So, a virtual particles have no direction in time. They just go up and down. Since the beginning of time and before — EugeneW

But up and down are opposite DIRECTIONS on a straight line. This could be perceived as the universe of 'lineland,' such a universe could still support linear time (past present future), so I don't get your 'virtual particles have no direction in time,' proposal. If they have no direction in time then they have no direction in space by virtue of spacetime. Does this not mean they can't actually exist and they are merely a convenient 'tool' to aid some current theories of the structure and workings of the Universe.

So, a virtual particles have no direction in time. They just go up and down — EugeneW

The wave function is a complex-valued probability amplitude — universeness

Is it the quote above from wikipedia, that 'marries' with your 'goes up and down' proposal?
The idea of a wave 'amplitude,', if so, an amplitude must take time to form an it forms in a direction from rest to up (in the case of a crest) or rest to down (in the case of a trough). Does this marry with the proposal of 'rest up to crest as current to future' and 'rest down to trough as current to past?'

Real particles have a direction in time. They move forward in time. A virtual particle goes forwards, backward, forwards, backwards, forwards, etc. This fluctuation is often popularized as a pair, a particle-antiparticle pair, created and annihilating each other, while in fact there is just one eternal particle (seen from the collective of real particles going forward).

I cannot understand EugeneW, so I don't think an explanation of what I mean is going to come from him.
— noAxioms

He has been quite patient with me when I have demonstrated my limited knowledge of physics. He has demonstrated his deeper grasp of the topic and has not 'dismissed' me as 'not worth his efforts.' As a retired school teacher myself, I appreciate and celebrate his approach and passion for physics and I prefer it to the more pretentious and unwarranted, almost sad, aloof attitudes of other members of this forum, be the thread philosophical, scientific, religious or political. Thankfully, such attitudes are also in the minority on this forum. — universeness

Thank you @universeness ! That's good to hear!

A wavefunction, in relation to qft, can be considered as a temporal cross section of a particles free field. A particle litterally travels on all possible pathways through spacetime. All paths have a probability, and are taken at the same time. In hidden variables theory, they hop from one to the other. No wonder these variables are non-local, and I have never understood why the fact that there are no local hidden variables is such a big deal. That's exactly what they don't have to be. In that theory, the wavefunction is a physical entity. Its squared, that is. It's a wavefunction because it's derived from the same equation as a real wave equation.

Carlo Rovelli is great. He's something else, like Smolin. Must be his "Italian blood". All particles need interaction to identify themselves. By interaction they can show their quantum numbers. Which is almost equivalent to their charges. There are leptons and quark numbers. But these are not thought to be fundamental. Which is naturally the case in preon theory. There are only three kinds of massless charges in that theory. All moving within the space sauce of hidden variables.

How did you do that @universeness profile link. That's one of the things I was asking the elusive 'Baden' mod about and relates to the 'general' post I made at the top of this page.

Here's a fun aside, every time I type 'mod' instead of moderator, I get images of a large group of mad teenagers wearing fishtail parkers with Harrington jackets and turtle neck pullovers underneath and mostly white drainpipe trousers, driving Lambretta scooters whilst heartily singing in loud unison:
"We arra mods, we arra mods, we are we are we arra mods! repeated ad Infinitum and ad nauseam.
As they search for an equivalen group on 'Rockers' on real motorbikes who they invariably got beat up by. Go figure my thought processes? Perhaps I need some time with an analyst:
We arra mods, we arra mods...............

The idea of a wave 'amplitude,', if so, an amplitude must take time to form an it forms in a direction from rest to up (in the case of a crest) or rest to down (in the case of a trough). Does this marry with the proposal of 'rest up to crest as current to future' and 'rest down to trough as current to past?' — universeness

I'm not sure I understand. You mean time going forwards and backwards in a wavefunction, depending on the position in the wavefunction?

It's a bit hard to visualise, because we are used to particles going forward in time with definite position and energy, mutually related. If energy is zero then momentum squared is $-m^2$, according to $E^2-p^2=m^2$, and this relation doesn't hold for virtual particles. They can have independent values to fit the boundary conditions of two asymptotically free particles. In other words, if the two incoming particles have specified E and p, as the outgoing ones, the virtual particle adjusts to fit these values. It could also adjust to other values. All have certain amplitudes to occur. Qft calculates these scattering amplitudes by means of Feynman diagrams.

I ama member... press the @, and fill in the name you wanna link: @universeness

A particle litterally travels on all possible pathways through spacetime. All paths have a probability, and are taken at the same time — EugeneW

Oh, This is Richard Feynman's mind, isn't it. Yeah, I have read about this many times in relation to the double-slit experiment. Never been able to get my head around this one. How can every possible path be traversed by the 'same' particle in an instant of time? I know I should not conceive of the speed of light as a limiting factor here but I don't understand how to do that.

How can every possible path be traversed by the 'same' particle in an instant of time? — universeness

That's exactly why hidden variables are invented! How can a particle have a probability to be here or there? Where is it then?

press the , and fill in the name you wanna link — EugeneW

But I did so in my post at the top of this page, have a look! It did not produce the link, why not?

Let me try again here: @EugeneW

Isn't there an @ on top of the comment space? With all the other symbols?

On my computer, the @EugeneW appears as just black text. Does it show as a profile link on everyone else view?

Right of the fat, quote, list, picture, and link...

Isn't there an on top of the comment space? With all the other symbols? — EugeneW

Ah! I was just using my keyboard @ symbol. Lets try the site @

@EugeneW

Gotcha!

Another problem solved, thanks EugeneW!

That's exactly why hidden variables are invented! How can a particle have a probability to be here or there? Where is it then? — EugeneW

Well, I understand the probability of an outcome as simply 1/all possible outcomes.
The probability of a particle having a particular 4 coordinate position (3 spacial and 1 of time), would I assume depend on its starting position and its known or predicted path.
But I would also assume that the 'geometric expanse' of the particle involved would also be a factor as to how much space it occupies at any instant of time.

Carlo Rovelli is great. — EugeneW

I second that emotion!

It's a bit hard to visualise, because we are used to particles going forward in time with definite position and energy, mutually related. If energy is zero then momentum squared is −m2−m2, according to E2−p2=m2E2−p2=m2, and this relation doesn't hold for virtual particles. They can have independent values to fit the boundary conditions of two asymptotically free particles. In other words, if the two incoming particles have specified E and p, as the outgoing ones, the virtual particle adjusts to fit these values. It could also adjust to other values. All have certain amplitudes to occur. Qft calculates these scattering amplitudes by means of Feynman diagrams — EugeneW

I was reading something similar to this on Wikipedia and a physics site. I also read a discussion on this on quora. I understand some of it but will have to do a much more detailed reading on it to improve my understanding. I think I need a very detailed example from a starting title such as:
'a day/hour/minute/second/plank time in the existence of an electron.'
There must be such worked examples available. If you know of such a link then I would appreciate it but I can do my own searching as well.
One to add to my 'to do' list or more accurately, my 'to improve my understanding of quantum physics' list.

I have brain damage. Sorry OP, can't help you. :grin: :point: Risus Sardonicus!

Imagine being an electron. A virtual one. You travel on all possible paths, with all possible values of E and p, forward and backward in time, at the same time. A real electron does the same, but only forward in time and with fixed E and p (or corresponding t and x, their conjugates, obeying uncertainty relations).

I have brain damage — Agent Smith

You should thank God on your knees!

You should thank God on your knees! — EugeneW

SILENCE, YOU PEASANT!

Imagine being an electron. A virtual one. You travel on all possible paths, with all possible values of E and p, forward and backward in time, at the same time. A real electron does the same, but only forward in time and with fixed E and p (or corresponding t and x, their conjugates, obeying uncertainty relations) — EugeneW

I wish I could imagine such and I have quite a vivid imagination, in my opinion.
I can only imagine virtual as it is proposed in virtual reality simulations, which I think is a very acceptable manifestation of the term applied to the 'science of reality,' as a human being might perceive it.
Earlier in our discussions on another thread, you stated that you had difficulty with the logic/evidence behind my predictions of the possible future transhuman manifestations which may become possible due to technological advancement.
I have similar or perhaps even more difficulty with the logic/evidence behind:

"You travel on all possible paths, with all possible values of E and p, forward and backward in time"

and
"A real electron does the same"

I know this is from Feynman and I hold him, as most people of science do, in very high esteem but it's when the words "This literally happens" that an electron travels on all possible paths through the slits in the double-slit experiment, that I have great difficulty with. I understand it as a 'mathematical thought exercise' of Feynmans and that he used this thought exercise to collapse all these paths into a single 'average' REAL physical path. I can make that 'logical jump,' but I can't conceive or accept that all possible paths are literally traversed by an electron or photon emitted by a source towards a screen behind two slits in a card placed between the source and the screen, producing the wave interference pattern viewed.

If you understand the wavefunction, then you should understand this. If you put cards parallel to the screen (in the double slit experiment) you would see the wavefunction (as on the screen). I don't think the particle travels on all paths at once. It rather jumps from one to the other, within the confines of the wavefunction the wavefunction accompanied the particle.

I have mixed emotions when it comes to the term 'metaphysical.' Definintions like 'after physics' or 'beyond physics' don't help but I normally do find some value when I read/view 'metaphysical' discussions. — universeness

Physics concerns what one expects to measure. Metaphysics concerns what is. So a quantum interpretation like Bohmian mechanics or RQM make zero empirical predictions, hence are not part of quantum mechanics physics theory.

Some molecule of Napoleon's dying breath interacts with the rock, changing the state (the momentum perhaps) of at least one particle of the rock. The rock is now different than it would have been without that measurement, thus Napoleon exists relative to that rock
— noAxioms

I may have garnished more value from this if you had typed something like 'Some molecule of Napoleans consciousness (not his dying breath), as his physical body starts to disassemble, after his death...interacts with a rock.

That breath was made of atoms, and electrons and protons and such. Those particles are still around to this day. They'd be somewhere else had Napoleon never existed, so they constitute a measurement of him.
To phrase it in MWI terms: It is not possible that there is a world that contains you (now and in your current state) and does not contain Napoleon.

I personally think this idea is nonsense and that such an interaction would leave the rock completely unchanged.

Hey, whatever floats your boat.

I think it's much more likely that disassembled component parts of a dead human consciousness

I don't think human consciousness is an assembly of components. More of a process that takes place, like combustion, involving not necessarily the same matter at any given time, just like a candle flame's atoms are almost completely different than the 'same flame' a minute later.

I base this on a comment made by a physicist on Quora:
"the worldline of light behaves as ligtht-like curves in spacetime"

Not to say anything against that particular quote which seems accurate, but I find Quora to be one of biggest sources of misinformation on the web due to the lack of mechanism to promote correct answers to questions. Physics.StackExchange is far better in this regard and I usually look there first. I'm not a registered user on either site.

Yes, so the picture of hubble deepest field image (I have a very large framed print of it in my bedroom) mainly contains objects which probably don't exist anymore.

Depends on your definition of 'exists'. They've been measured, so they exist to us by that definition. They're galaxies, and separate galaxies might merge into bigger ones, but they hardly just cease being there after only several billion years

There are no hidden variables in RQM, and humans do not play any preferred role.
— noAxioms
How do you know there are no hidden variables? — EugeneW

I didn't say there are no hidden variables.

That's exactly why hidden variables are invented! How can a particle have a probability to be here or there? Where is it then? — EugeneW

You seem all over the map with your 'facts', but without framing them with a specific interpretation, and almost all of them are interpretation-dependent 'facts'.
You seem to mix bits from RQM, Copenhagen, and Bohmian mechanics, only the latter of which actually suggests that a particle has a location even unmeasured. Bohm's efforts seem a desperate attempt to explain quantum mechanics in classical terms as if classical physics is the more fundamental of the two.
The interpretation (and only one other that I know of) holds to the principle of counterfactual definiteness: that any given particle is in fact in some defined state at any time even in the absence of measurement. In doing so, he discarded the principle of locality (that cause must precede effect), a principle I find harder to sacrifice. No valid interpretation holds to both principles.