Speed of light

[aristarchusinexile]

G'day from the land of ozzz

When the chinese whisper is applied to TIME, we end up with many fantasy models, of time machines, black hole dimensions and the actual ability to change time.

According to everything I've read, PHDs all of them, time travel is a definite reality which simply has not been done by our present civilization.

[aristarchusinexile]

All this tells anyone is that they need to learn the differences between melting and crystallization.

Q - a movie of sublimation of an ice cube played in reverse might appear exactly to be be a cube crystal forming.

[aristarchusinexile]

G'day from the land of ozzzzz

Here down under we have our time upside down and inside out.

OK

If time cannot change, what is all the who haa about time.

So far our method of time has been measured by several means.

If we use EMR to measure time than we have to understand what happens to the speed of EMR in various situations.

Under situations where C is contstant it becomes an easy calculation to calaculate the time from position A to position B moving or non moving.

If we have the extreme situation such as a so called black hole where the compact matter having extreme electromagnetic fields surrounding it effects the speed of light. Than the relative time can be calculated by the resultant speed of the EMR.

This becomes very difficult when the compact matter either forms a trapping Horizon or the theoretical Event Horizin where all EMR is trapped within the Trapping Zone of the compact matter (so called black hole)

Time is simple, we usully complicate it for better or worse.

Would it not be great to have a time machine? We can all dream.
What about santa?

"Time is simple" .. that's what we thought about so many things in the past .. gravity .. the entire universe. The concept that time is something only to be measured could be a hindrance to development of our thoughts about time .. because elements of time might be immeasurable. Time might actually be causative .. for instance, the simple saying 'he is a product of his time' .. might carry far more meaning than casual. I think we are stuck in the same place as the old shool of 'earth air water fire' with the four 'forces' .. I think time is a force, although I don't like to call these things forces, as 'force' implies brute power overcoming other powers instead of powers working together. Could time be like a 'fluid', carrying things along, creating energies and effects? I'm simply wondering .. not saying my thoughts are facts.

[aristarchusinexile]

Where such a free environment of gravity field reside. Because for now where ever we look we see the gravity field effect everywhere. All i read up to now is that the gravity field extand to infinity. It may be weak at some place but it is there even if weak. And dark matter seem to exist and also have a gravlty field. I'm curious about that new theory? Did i see you before?

I have been reminded of the vast "voids' in the universe in which, so far, we see absolutely nothing existing. Those voids, in my mind, are probably free of gravity, of they would not exist, having drawn into themselves the matter around. Our universe has been likened to Swiss cheese, with the holes in the cheese being the voids.

[Doum]

Why should gravity be forbiden to expand in a void. Void mean almost nothig in it but it is a place where there are few matter. A star all alone there will not be visible.
A void is space time without a lot of matter. It does'nt mean "without the gravity field" of all the galaxies that surround it or all galaxies clusters that surround it. Gravity deform space time. It even close spacetime on itself (Black hole). So i dont see any reason why gravity should be forbiden in a zone of spacetime that is almost empty.

[astrolabe]

Hello All,

Just a quick thought on the idea of light traveling instantaneously in voids. If it were so then light from structures on the far side of the void would exhibit a characteristic redshift signature that would be not that far off from the redshift signatures of structures on the nearside of the void resulting IMHO in the phenomenon that the void does not exist at all. IOW, we as observers would think there was no void or spatial separation between the two. We detect the voids because of the redshift differential. Corrections concerning this argument are more than acceptable.

P.S. with regard to gravity within the voids: if one agrees with the DM proposal then one assumes that the voids are filled with it and it's very presence would be necessary for the voids to exist.

[bystander]

Just a quick thought on the idea of light traveling instantaneously in voids. If it were so then light from structures on the far side of the void would exhibit a characteristic redshift signature that would be not that far off from the redshift signatures of structures on the nearside of the void resulting IMHO in the phenomenon that the void does not exist at all. IOW, we as observers would think there was no void or spatial separation between the two. We detect the voids because of the redshift differential. Corrections concerning this argument are more than acceptable.

I think your assessment plausible, the voids would be undetectable if light traveled instantaneously across them. The difference in red shift makes them detectable.

P.S. with regard to gravity within the voids: if one agrees with the DM proposal then one assumes that the voids are filled with it and it's very presence would be necessary for the voids to exist.

DM is detected by its gravitational influence on visible matter. If the voids were filled with DM, they would attract visible matter. I don't think there is any evidence of this. I also think that if the void was filled with DM, it would act as a gravitational lense, not a void. Just a reasoned opinion.

[astrolabe]

Hello Bystander,

Yes I agree with your response concerning the liklihood that DM is probably not present in the voids. unless the density is negligible. Seems more likely now that DE fills the voids? In any respect I'm ready to void/avoid the subject for the time being but it has been good brain food nonetheless.

[Qev]

All this tells anyone is that they need to learn the differences between melting and crystallization.

Q - a movie of sublimation of an ice cube played in reverse might appear exactly to be be a cube crystal forming.

It might appear the same in a simple video, but that would only be due to a lack of information provided to the viewer. The melting of a crystal and the formation of a crystal from a liquid are effectively each other's reversal, but our friend entropy only lets the clock run one way.

[aristarchusinexile]

Ah, but Q, it is only our lack of information which suggests to us that we "know" what we in reality do not know.

As far as entropy goes, an article in an up to date science magazine in a public library tells me that the 'rules' of entropy break down in environments lacking symetry, equilibrium .. that despite entropy, order arises from chaos. So .. if time is not just a simple tool for measurement, if it is an active medium, it too might be able to disassociate from entropy .. normal entropy causing time only to run forwards towards ultimate chaos in one standard model, but possibly, because that standard order is in reality chaos itself, reaching an order where time diverges into reversal, sideways, or circular motion. I'm sorry I can't reference you to the magazine, even the memory of the title of it is murky, Science News perhaps .. I read it two weeks ago, and have read several other publications of all sorts since then, and I don't keep records.
I should say that my application of Time to the article comes from my own thoughts, there was nothing in the article suggesting Time in the way I picture it.

[aristarchusinexile]

Why should gravity be forbiden to expand in a void. Void mean almost nothig in it but it is a place where there are few matter. A star all alone there will not be visible.
A void is space time without a lot of matter. It does'nt mean "without the gravity field" of all the galaxies that surround it or all galaxies clusters that surround it. Gravity deform space time. It even close spacetime on itself (Black hole). So i dont see any reason why gravity should be forbiden in a zone of spacetime that is almost empty.

I just have to repeat that if gravity existed in a void, the void would probably not exist, because the gravity would have drawn into the void the surrounding matter. I don't think it is just the result of insufficient time passing since the universe began that allow the voids to remain.

[aristarchusinexile]

Hello Bystander,

Yes I agree with your response concerning the liklihood that DM is probably not present in the voids. unless the density is negligible. Seems more likely now that DE fills the voids? In any respect I'm ready to void/avoid the subject for the time being but it has been good brain food nonetheless.

You two guys sure cause a guy to think.

[bystander]

The Second Law of Thermodynamics is an expression of the universal law of increasing entropy, stating that the entropy of an isolated system which is not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium.
...
There are many versions of the second law, but they all have the same effect, which is to explain the phenomenon of irreversibility in nature.

Because of this irreversibility, entropy is often called Time's Arrow.

[Doum]

I just have to repeat that if gravity existed in a void, the void would probably not exist, because the gravity would have drawn into the void the surrounding matter. I don't think it is just the result of insufficient time passing since the universe began that allow the voids to remain.

When the universe start to expand, spacetime was everywhere and it is still everywhere in the universe. Matter start to form star and galaxies and as it collect matter from the zone that have less gravity a void have no choice but to be create. Even if gravity bent spacetime is does not create it. So spacetime is the same everywhere except near a gravity field where it is very very very slightly change. So the void are not realy affect by gravity even if it's there because that gravity is extremely weak or almost non existant but spacetime is still there as everywhere else in the universe. I dont see no reason to think any other way.

[Qev]

Well, remember, gravity doesn't bend spacetime, gravity is the bend in spacetime.

[harry]

G'day bystander

You said it quite simple,,,,,,,I like it

[bystander]

Thanks, Harry, but I can't take credit. The first part (in italics) is from wikipedia. I read aristarchus' post about entropy and time and I vaguely remembered the bit about the arrow of time (Hawking?). I did a wiki search and came up with what you read. Follow the links.

Time flows in one direction only, and entropy points the way.

I think that's a quote, but I don't remember where I saw it.

[bystander]

Aristarchus

You seem to be fond of quoting Stephen Hawking. Here's a few for you from A Brief History of Time.

The theory of relativity does, however, force us to change fundamentally our ideas of space and time. We must accept that time is not completely separate from and independent of space, but is combined with it to form an object called space-time.

"We see the universe the way it is because we exist."
...
there are either many different universes or many different regions of a single universe, each with its own initial configuration and, perhaps, with its own set of laws of science. In most of these universes the conditions would not be right for the development of complicated organisms; only in the few universes that are like ours would intelligent beings develop and ask the question: "Why is the universe the way we see it?" The answer is then simple: If it had been different, we would not be here!

One could say: "The boundary condition of the universe is that it has no boundary." The universe would be completely self-contained and not affected by anything outside itself. It would neither be created nor destroyed. It would just BE.

Imaginary time is indistinguishable from directions in space. If one can go north, one can turn around and head south; equally, if one can go forward in imaginary time, one ought to be able to turn around and go backward. This means that there can be no important difference between the forward and backward directions of imaginary time. On the other hand, when one looks at "real" time, there's a very big difference between the forward and backward directions, as we all know. Where does this difference between the past and the future come from? Why do we remember the past but not the future?

[aristarchusinexile]

The article I read takes those things into account, Harry and Bystander, but I suppose you both know we well enough by now to know I cannot accept standard versions as law, especially when there are so many exceptions within those versions, such as order being created out of chaos, and when we are merely at the beginning of knowledge and understanding of how our universe operates. According to what I've read in the past several weeks, solid books by solid PHDs with solid positions in the accademic and publishing world, not only is time travel a totally doable thing given technology and energy source, but time manipulation is possible as well. It seems only a matter of progression to say if we can manipulate time .. we can reverse it.

[aristarchusinexile]

Aristarchus

You seem to be fond of quoting Stephen Hawking. Here's a few for you from A Brief History of Time.

The theory of relativity does, however, force us to change fundamentally our ideas of space and time. We must accept that time is not completely separate from and independent of space, but is combined with it to form an object called space-time.

"We see the universe the way it is because we exist."
...
there are either many different universes or many different regions of a single universe, each with its own initial configuration and, perhaps, with its own set of laws of science. In most of these universes the conditions would not be right for the development of complicated organisms; only in the few universes that are like ours would intelligent beings develop and ask the question: "Why is the universe the way we see it?" The answer is then simple: If it had been different, we would not be here!

One could say: "The boundary condition of the universe is that it has no boundary." The universe would be completely self-contained and not affected by anything outside itself. It would neither be created nor destroyed. It would just BE.

Imaginary time is indistinguishable from directions in space. If one can go north, one can turn around and head south; equally, if one can go forward in imaginary time, one ought to be able to turn around and go backward. This means that there can be no important difference between the forward and backward directions of imaginary time. On the other hand, when one looks at "real" time, there's a very big difference between the forward and backward directions, as we all know. Where does this difference between the past and the future come from? Why do we remember the past but not the future?

I read the book, Bystander .. and I quote Hawkings because his name seems to be at present most recognized, but like every human Hawkings has partial knowledge only, and I read other books and magazines as well, like

Tyson and Goldsmith: "Calculations of the amount of Dark Energy that lurks in every cubic centimetre produce a volume about 120 powers of ten greater than the value that cosmologists have found from observations of supernovae and the cosmic background radiation.
'Origins' – published 2004.

Pascual Jordan - "A star could be made out of nothing at all, because at the point of zero volume its negative gravitaional energy would precisely cancel out is positive mass energy."

Einstein – "We now realize, with special clarity, how much in error are those theorists who belive that theory comes inductively from experience. Even the great Newton could not free himself from this error."

'Edge of Time' P.73 – of Bade and Zwicky's proposal for neutron stars forming from Supernovae: "The proposal, coming just two years after the discovery of the neutron, was a much more daring leap of intuition than it may seem…"

Tyson and Goldsmith: "Astrophysicists also lack any known mechanism to create technetium in a star's core and to have it dredge itself up to the surface where they observe it."

Simon Clement (NASA) – "We really know less and have more questions about the beginning, now that we see this stuff in nature." (Brownleeite from comet 26P – 'Science', July 5 2008.

"The lightest supersymetric particle is thought to have no charge, and to interact only weakly, which is why it is a candidate for the invisible Dark Matter. As such, the particles would be be seen in a a detector, hence the energy it carries would be missed." Science News July 19/08

John Gullin – Unveiling the Edge of Time – P. 98
Speaking of the history of a blue star radio source: "Since the distance of 3C48 is unknown there is a remote possibility that it may be a very distant galaxy of stars; but there is a genral agrement among the astronomers concerned that it is a relatively nearby star with most peculiar properties." (quoted from Sky and Telescope vol. 21 page 148 1960) "That was still the concensus at the beginning of 1963. Within a few months, however, investigations of yet another of the 3C sources had shown that the consensus was wrong."

All of my reading tells me clearly we do not know much right now, and this seems to be agreed to by those writing the mainstream books I've been reading, compared to what we will know even in two more years. Observational and computational instruments, and theoretical progression are under construction now which will, in ten years, relegate today's cosmology to relatively ancient history. This is not an insult to today's scientist any more than what Olympic athletes ten years from now being insulting to todays athletes .. today's athletes are learning from yesterdays, next year's athletes will be learning from today's. It's the same in science.

[Doum]

Yes you're right, what if i say that all mass bend spacetime and that "bend spacetime" is call gravity. More gravity from a mass make more bend of the spacetime. And spacetime is everywhere in the universe. If there aint any mass somewhere then spacetime is not bend but it is still there.

[Chris Peterson]

Yes you're right, what if i say that all mass bend spacetime and that "bend spacetime" is call gravity. More gravity from a mass make more bend of the spacetime. And spacetime is everywhere in the universe. If there aint any mass somewhere then spacetime is not bend but it is still there.

Qev's way of expressing it is most accurate. You shouldn't talk about gravity from a mass bending spacetime. It is the intrinsic nature of mass to distort spacetime, and it is the effects of this distorted spacetime on mass that we call gravity. Mass doesn't have gravity.

[bystander]

I think what Doum is trying to say is mass distorts spacetime and the greater the mass, the greater the distortion.

[Chris Peterson]

I think what Doum is trying to say is mass distorts spacetime and the greater the mass, the greater the distortion.

I think so, too. I just think Qev expressed it in a better way.

[Doum]

Yes you're right, what if i say that all mass bend spacetime and that "bend spacetime" is call gravity. More gravity from a mass make more bend of the spacetime. And spacetime is everywhere in the universe. If there aint any mass somewhere then spacetime is not bend but it is still there.

Qev's way of expressing it is most accurate. You shouldn't talk about gravity from a mass bending spacetime. It is the intrinsic nature of mass to distort spacetime, and it is the effects of this distorted spacetime on mass that we call gravity. Mass doesn't have gravity.

I think what Doum is trying to say is mass distorts spacetime and the greater the mass, the greater the distortion.

I think so, too. I just think Qev expressed it in a better way.

I agree too. English aint my language plus my understanding of astrophysic not being that great i find it hard to explain. But i try anyway so you guys can correct me. Many thanks. Now in that sentence "It is the intrinsic nature of mass to distort spacetime, and it is the effects of this distorted spacetime on mass that we call gravity" i understand this Mass distort spacetime and that distort spacetime affect the mass. Now i am not sure i understand it. should it be said instead "it is the effects of this distort spacetime we call gravity" . ? Wich happen to affect the mass. Ohhh need to rethink it now.