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Physics, Astronomy & Cosmology / How would we know whether space,time or spacetime were continuous or discrete?

« on: 11/06/2022 11:30:59 »

I understand that we have no answer as yet and my intimation  is that we may never know (although "we" may build a satisfactory model based on either supposition.)

In the meantime, what indications are there that one of these two paths might eventually bear fruit?

Is it all going to boil down    to some clever person devising an experiment that more or less rules out one of the options or  can some possibilities already be ruled out on the basis of existing understandings?

Suppose ,say one was investigating a possible discreteness, at what level might that be conjectured to occur -and would some mechanism be required to cause this or would  we reach the end of the chain of causality at that point?

(as an aside  ,does the thinking process have to follow the same laws and are our minds forbidden to imagine possibilities  at some deep physical level no matter how unrestrained our imagination can appear to us? Even imagination would be tethered?)

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Just Chat! / Is life built into the fabric of the Universe?

« on: 02/02/2022 15:11:01 »

Is/was life an accident  or an accident waiting  to happen?

Can we conceive of any universe (one with different "initial" conditions)  that would not ,at some stage evolve into a stage for life ,no matter how primitive?

Are there any theories that convincingly posit a universe of finite extent(both time and space) where it might be possible for life never to have evolved?

Or is this finite extent precondition  unconvincing?

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Physics, Astronomy & Cosmology / Anyone listen to Brian Cox's Universe on BBC4 ?

« on: 29/10/2021 13:16:57 »

Specifically where he seems to claim that the first stars were formed at the intersections of the filaments of Dark Matter.

Is this accepted and established science?

Apart from that I was quite impressed by his description of DM.Quite matter of fact  and no theatrics,in fact as if it was pretty well understood apart from not being observed with em radiation

Of course Dark Energy ,which hasn't  come up yet in his new series is a different kettle  of fish  and rather more startling imo.

Out of secondary interest I was going to post this on one of the other forums I post in ,scienceforums.net but one of the mods there  from San Diego,I think had a public run in with Brian Cox some years ago and it might have been a red flag to a bull
https://www.scienceforums.net/topic/64562-a-quick-glance-at-brian-cox-is-full-of-it/page/2/#comments

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Physics, Astronomy & Cosmology / What if the universe really is infinite?

« on: 18/10/2021 13:02:08 »

Watching a Horizon programme last night on BBC 4 (Sean Caroll was one of the contributers)

Apparently the Cosmic Microwave Background Map is like an expanding bubble around anywhere in our "neighbourhood" and its features have now been mapped in enough detail to "draw" a huge triangle from here to there.

The triangle ,according to the programme is evidence that  space (spacetime?) is probably flat and as a result the universe outside the observable part is  of infinite extent.

What might be the implications if this,startlingly  is true and can we now posit this provisional result as a stone to build our edifice of how "everything" works.

Can we ditch the "universe may be finite" for good unless we get  some new unexpected observations in the coming years or centuries?

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Physics, Astronomy & Cosmology / Is everything fundamentally quantum?

« on: 16/10/2021 13:58:15 »

Are there any classical behaviours that cannot be said  to be quantum to some degree?

Are there any theoretically possible tweaks to quantum behaviour  that would change the way the macroscopic  world would behave?

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Physics, Astronomy & Cosmology / Could mass be considered as an excitation of the gravitational field?

« on: 09/10/2021 15:54:40 »

Perhaps I am just regurgitating scientific jargon ,but might it be another way of looking at the relationship between mass and the gravitational field(which I think I may have told is not to be viewed as a physical object and rather a set a of measurements)

Anyway ,does my question have any merit?

Also,however defined , can we imagine the gravitational field to have been established in its initial form  after the BB and to be metamorphosing (changing shape) ever since

I think Einstein  may have used the "mollusk" description about it.

https://www.physicsforums.com/threads/what-einstein-meant-when-he-termed-something-a-mollusc.391139/

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Physics, Astronomy & Cosmology / Is the sequence of physical events continuous or discrete?

« on: 04/10/2021 00:14:03 »

Suppose I am washing my face some time tomorrow.

Within my body there will be many events occurring during that time.

I am no chemist but one might be that there is a reaction  between an atom of carbon and an atom of iron in my hand.

Whatever the particular reaction (and I assume there will also be reactions within that reaction) there will be a previous event that can be said to have "immediately" preceded or caused that iron/carbon event.

Will that earlier event be distinct from the (iron/carbon) event that followed or are these two events  connected in a continuous way?

I understand that particles are now modeled as being properties of an underlying field.Are these fields  believed to be continuous or discrete in nature?(in the model,I suppose I should say)

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Physics, Astronomy & Cosmology / How does the electron field get excited so as to produce an electron?

« on: 13/09/2021 15:47:30 »

I have been scratching my head as to how an electron creates an electron field.

Then I recall that it  the electron is considered as an excitation of the electron  field.

Then I recall that the field is just a  number of measurements (made with electrons?)

So what is is that  produces the excitation in the field?

Do these excitations  produce their own fields  ?Do these fields  add together  constructively and can they cancel out like waves?

And are these fields all in relative motion?

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Physics, Astronomy & Cosmology / What's the relationship between the speed of information and the speed of light?

« on: 29/08/2021 10:33:23 »

(for slow learners    )

I see  there have been  recent/ongoing interesting threads already and I doubt this is breaking any new ground ,even semanticly but here I go.

I have heard that the nature of speed of light in a vacuum   may be better understood as reflecting the maximum speed of transfer of information in the universe.

So is there any sense in which  light and information are joined at the hip?

Can information be transferred
without the mediation of a light signal? ( in either a practical or a theoretical sense)

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Physics, Astronomy & Cosmology / Why do objects travel through space-time and not space and time?

« on: 22/08/2021 02:38:52 »

I understand that space and time are interchangeable and that there is a conversion factor ,c that allows one to see one as a function of the other.

Would I be on the right track if I was to interpret these  understandings in the following way?

We do not travel through space  and neither (more intuitively) do we travel through time.


We just travel (follow entropy?)  and our progress relative to our environment is measured either in terms of spatial intervals or  temporal  intervals.

Would that interpretation be anyway along  the right lines?

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Physics, Astronomy & Cosmology / Are possibly all massless particles just travelling waves in particle fields?

« on: 05/08/2021 21:36:15 »

That is an uneducated question and I anticipate answers  along the lines of "of course not",

Still the idea of that possibility just occurred to me .Is there /could there be anything to it at all?

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Physics, Astronomy & Cosmology / Can it be shown that there must be a maximum relative speed attainable ?.

« on: 26/05/2021 03:54:33 »

...in any system (eg the knowable universe ) whether finite or infinite?

If so what factors might  determine its value?

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Physics, Astronomy & Cosmology / Can we see the universe from the outside?

« on: 05/05/2021 01:36:43 »

Clearly this is something I cannot do insofar as I am presumably a part of this universe (and I think it is also said that the universe has no external boundary).

However is it not possible that the  beginning(if there was a beginning) of the universe was witnessed by an intelligent being (or even just another object?)  and so this being or thing would have had something of an objective view of what happened?

Is that feasible  ?

Would that mean that the universe  did in fact  have a  boundary, even if that boundary  was dynamic and poorly defined ?

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Famous Scientists, Doctors and Inventors / Will I post a link for some new Feynman videos here?

« on: 02/04/2021 17:00:38 »

http://www.thescienceforum.com/links/50272-newly-presented-feynman-lectures.html

I like them a lot  since they are good quality and maybe this is a good place to post a link to them?

https://www.feynmanlectures.caltech.edu/

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Physics, Astronomy & Cosmology / How does mass-energy curve spacetime?

« on: 19/02/2021 04:24:43 »

I am fairly sure,based on what I have heard that the answer is that we do not yet know the answer to this.

However ,are there any serious ideas as to what the actual mechanism might be ?

I imagine it might be somehow based on  fields  since that seems to be the predominant area of theory concerning very small object's,which may be the level where spacetime curvature occurs.

But I have extremely little insight into this area.

Are there any theories or hypotheses that could make some sort of sense to a layman?

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Physics, Astronomy & Cosmology / What happens to the spacetime interval between two events as they approach a BH?

« on: 17/02/2021 16:13:28 »

....or any similar object that curves spacetime?

ie how does the r/t ratio in the s^2= ct^2-r^2  formula change?

Edit :I don't mean the same event ,of course .I mean  identical events whose spacetime intervals are measured as they approach the source of gravity.(Perhaps  light reflecting between two mirrors would do - or two hypothetical events involving massive objects)

Reedit: the event pairs  are causally connected.

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Physics, Astronomy & Cosmology / Are there any serious ideas floating around about Wormholes?

« on: 21/12/2020 14:38:31 »

I have heard that they could be a consequence of intense gravitational environments where the spacetime curvature "shears" in some way.

Are there any coherent ideas going the rounds as to what consequences might follow if this idea had any firm basis and was able to be verified in some way?

What might observers of the sky be on the look out for example?

Something enormous?. Something tiny ? In between?

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Physics, Astronomy & Cosmology / What is the smallest theoretical magnet?

« on: 14/12/2020 01:16:48 »

I see that a single atom can be described as a magnet,

https://phys.org/news/2017-03-ibm-world-smallest-magnet.amp


Is it possible to go smaller?

What if two (or 3?) individual  electrons interact with each other?

Do they create a magnetic field?

Can one group of electrons be considered as a "magnet" to the other ,single electron?

Does the interaction of 2 or more electrons always (ever?) produce em radiation?

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Physics, Astronomy & Cosmology / How does light move in a vacuum?

« on: 27/11/2020 15:54:34 »

I understand that em waves propagate as disturbances in the em field (correct?)as an expanding sphere centred on the point of emission.

What is the actual mechanism that causes this propagation effect?(I "know" that the electric field  creates a magnetic field and vice versa)

Is it connected to the action and reaction effect that allows rockets to move in a vacuum?

Is it valid to ask what happens if there is no pre-existing em field for the  wave to propagate through?

Would that be nonsensical ?

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Physics, Astronomy & Cosmology / What is a small classical example of em radiation?

« on: 22/06/2020 14:24:01 »

 I am trying to find an example of an extremely small electric charge moving wrt to  a magnetized conductor and causing  a photon to be created.

I understand that this can be seen as a classical or as a quantum phenomenon and so I would like to understand it classically in as microscopic a way as possible and then to try and understand it in the Quantum explanation (although I anticipate this as  being very challenging  for me)