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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 10/12/2018 22:35:57 »

And talking of death! If I die and no longer observe time passing and experience change no longer, does time still exist?

Yes, otherwise your body would not decompose.

22

Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 10/12/2018 11:56:16 »

Hi, Set fair; it's always good to look back to the OP when thread drift has moved the discussion away. Mea culpa

If I said time is the measured rate of 'change' then does change happen much slower away from the force of gravity throughout the whole universe?

My “layman” thought is that time is, as you suggest, a measure of rate of change. It becomes convenient to talk of changes in the rate of time’s flow, or of the rate of our passage through time, and to treat time as though it were an entity with existence that was independent of the things being measured and those doing the measuring; which may not be the case.  It certainly streamlines scientific thought and discussion. 

Thinking along those lines suggests that change does happen at different rates in different gravitational situations; however, reference frames and observer dependence must not be overlooked.

23

Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 09/12/2018 15:17:45 »

A “timely” thought experiment

“In a galaxy far away”, there exists a star identical to our sun, with an identical “solar system”.
Earth is planet A with physicist A (PA) and clock A (CA).
Earth’s twin is planet B with physicist B (PB) and clock B (CB).
Each physicist can see his own clock and the other’s with no time delay for information transfer.

Three assumptions:

1.  PA and PB each sees time passing at 1 sec per sec on his own clock.

2.  Each physicist sees the rate of time on the other’s clock as unaffected by gravity.

3.  Any difference between the perception of the rate of time between CA and CB, observed by either physicist, will be due to the degree of relative motion between the two galaxies; or relative motion resulting from differential motion within the individual galaxies.

24

Physics, Astronomy & Cosmology / Re: Do photons have mass?

« on: 04/12/2018 22:13:26 »

I’m just trying to get my head round the idea of proper mass, inertia etc, in another thread; so I’m going to have a go at this, to see how I’m doing.

I may be confusing “rest mass” with “proper mass” (possibly they are the same), but let’s start with rest mass.

This is the mass of an object as measured by an observer who sees that object as stationary. We can never observe a photon as being stationary, so we cannot assign it a rest mass. 

However, the photon has inertia, so it adds to the inertia of any system of which it is a part.  Because of the relationship between inertia and mass, the photon must, therefore, contribute mass to that system.

25

Geology, Palaeontology & Archaeology / Re: Can wind weather limestone?

« on: 06/11/2018 11:46:51 »

Hi Jacob, welcome.

It is probably important to distinguish between weathering and erosion.  Weathering is the process by which rocks are weakened and/or broken down, or dissolved.  Erosion is the process by which material, once subjected to weathering, is removed.

In the case of aeolian (wind) effects the picture may be blurred by the fact that the wind itself is generally not what does the weathering, rather, it is material carried by the wind that weathers the rock.  The wind may then do the transporting (erosion) of the weathered material.

Did you have a specific instance in mind?

26

Just Chat! / Re: Would it be wrong to try to get somebody kill themselves?

« on: 13/10/2018 19:17:59 »

Anyone particular in mind?

27

Geology, Palaeontology & Archaeology / Re: What is the name for this form of arch-like geological structure with fractures?

« on: 24/08/2018 22:43:36 »

Hi Geo4dood, welcome.

The left side of the arch looks as though it has parallel surfaces, which could be bedding planes.  This would suggest it is a sedimentary rock that has been folded.  Having said that, I've seen weathered granite domes that have shown quite similar features. Some more details would be valuable.  Where is it?

The fractures at right-angles to these "planes" are likely to be stress fractures.

The structure is an anticline.

I'm only an amateur, and it's a long time since I dabbled in any geology, so hopefully the experts will chip in.

28

Physics, Astronomy & Cosmology / Re: False Vacuum; Who, What, Where, When, Why?

« on: 24/07/2018 23:50:06 »

I’ve found some things that seem to conflict, (surprise!).

One image is that of a scalar field resting with stability in the lowest valley.

Contrast this with statements like: “the bottom of the valley into which the sphere rolls is considered to be the true vacuum, and this is where the scalar field discharges its energy.”

There seems to be a dichotomy between resting in the bottom of the valley, and that “fireball” of elementary particles, mentioned earlier.

The most sensible way round this, that I could see, was that the unstable quon came to rest in the bottom of the valley, discharged its energy and became a stable, expanding, universe.   Does that seem reasonable?

29

Physics, Astronomy & Cosmology / Re: False Vacuum; Who, What, Where, When, Why?

« on: 24/07/2018 20:46:41 »

I would view the higher valleys as tarns - lakes cut off from lower areas.

So far, so good.  Considering a landscape in which a false vacuum state is represented by a valley at an elevation higher than the true vacuum; this would provide the necessary stability. 

What is it that is stable in these valleys?
This necessitates looking at the “inhabitants” of the landscape; often depicted in Pop Sci books as little spheres that can roll about on the hilly landscape.  The best identification of these spheres I have found is that they are scalar fields.  Their energy is dictated by the vertical position they occupy, at any given instant, on the landscape. 

How big are these scalar fields? 
This is a question that is commonly ignored, possibly with good reason, but in developing his argument about the origin of the universe, Vilenkin treats them as quantum objects.  Presumably, this is how we should see them in order to progress to your comment on quantum tunnelling.   

30

Physics, Astronomy & Cosmology / Re: False Vacuum; Who, What, Where, When, Why?

« on: 23/07/2018 20:17:35 »

  The current understanding is that our vacuum has a positive energy equivalent to the mass of three hydrogen atoms per cubic metre, not a lot, but enough to have an enormous impact. 

    In theory, a false vacuum is a higher-energy version, and is characteristically unstable.  Typically, it decays into true vacuum in a small fraction of a second, and its energy is released in a “fireball” of elementary particles.   
 
    In trying to establish a non-technical image of the vacuum, and its energy, the best analogy I found was that of an irregular surface of waves and troughs representing this energy, and considered as a “landscape”.  The bottom of the lowest valley is considered to be the “true vacuum”, that in which our Universe exists.  Crests of waves, and the slopes linking them to the valleys, represent “false “vacuum” states in which the vacuum energy is higher.  Essentially, these are very unstable states. 

31

Physics, Astronomy & Cosmology / Re: Can time emerge?

« on: 16/06/2018 13:32:11 »

A related concept (looking through the other end of the telescope): Can time disappear?

This is subject to the same proviso as is the original question; namely, how do you define time?

If time is just a measure of change, the question should be: can change "disappear"?

32

Physics, Astronomy & Cosmology / Re: Is Einstein Wrong?

« on: 14/06/2018 12:08:32 »

http://www.ewh.ieee.org/soc/pes/switchgear/presentations/tp_files/2010-1_Lunch_Montillet.pdf

I've not read this, and I'm not sure I intend to, but if you're interested it Einstein's mistakes, it could be a good place to start.

It's worth remembering, though, that Einstein had a disconcerting habit of being "right" even when he was "wrong"

33

New Theories / Re: Was a white hole the source of the Big Bang?

« on: 01/06/2018 21:47:56 »

  A zero energy universe requires that the sum total of energy is zero.

That’s an interesting concept.  Surely there are two interpretations of a zero energy universe.

1. A universe that contains no energy.

2. A universe which contains equal quantities of -ve and +ve energy, so the net is zero.

There must be a distinction (?)

34

Geology, Palaeontology & Archaeology / Re: What rock did I find?

« on: 27/05/2018 19:34:11 »

Hi Lucasorun, welcome.

It's also a long time since I did any geology, and only as a hobby, so there are going to be others who can probably be of more help.

If your knife has a good quality blade and won't scratch it, you are probably right about the quartz.

Do you have reason to think the pink bits are inclusions of a different mineral?

If not, they could be rose quartz.  However, in my (limited) experience, specimens containing clear and rose quarts often do not show such well defined boundaries.
 

35

Guest Book / Re: Superb Essay Writers

« on: 25/05/2018 23:36:04 »

Our best essay team offers an in-dwelling proofreading power team

Perhaps someone should have "proofread" this post.

36

New Theories / Re: Re: Critique of scientific method and will we ever find a theory of everything?

« on: 21/05/2018 13:03:45 »

I'm not a fast reader, in fact I'm mildly dyslexic, so reading can be slow.  As I said, time is very limited and I would want to base any comments on a thorough look at the material, so, no promises, but I will post any thoughts I might have. Just don't hold your breath.

37

Just Chat! / Re: Is Donald Trump a ventriloquist's dummy ?

« on: 21/05/2018 12:47:50 »

My wife says the Antichrist would be taller and better looking!

38

New Theories / Re: Re: Critique of scientific method and will we ever find a theory of everything?

« on: 20/05/2018 16:25:26 »

I always like to have a look at something different, but after I brief followup of your links I have to say that I will probably not spend much of my very limited time reading a lot more.  I found the verbiage off-putting, and wonder about the testability of a theory that has a large number of hyperspheres at its heart; given that, as far as I am aware, no one has shown that a hypersphere is anything other than a mathematical concept.

I'm open to conversion, though.

39

Physics, Astronomy & Cosmology / Re: What is MCRF?

« on: 17/05/2018 12:57:01 »

Not something I could help with, but in the seeming absence of informed replies, it's worth asking if you have been here.

https://physics.stackexchange.com/questions/93022/exact-definition-of-momentarily-comoving-reference-frame-mcrf

40

Physics, Astronomy & Cosmology / Re: How do we know what the time is?

« on: 12/05/2018 01:37:09 »

Can you ask me that again last week please?

I thought about that next month, but thought not.

Let’s take your last point: It must be possible to propose a universe in which nothing is happening, but in which things did happen previously.  Chocolate may have come into existence then and might still exist – doing nothing – in a universe in which nothing is happening.

Time would have existed, and had meaning, previously.  The chocolate continues to exist for a non-specific period; we have no way of knowing if that period will end; but in order to define it as a period, time must have meaning.

Ergo, chocolate and time can exist, and be defined in a universe in which nothing is happening.