Speed of light

[harry]

G'day from the land of ozzzzz

You can read a thousand papers on time travel, and we all wish it could be so. The reality is that it is not possible. Yes I have read the papers and I can refer many also supporting time travel.

Time is not an item that can be altered changed in any way.

[Doum]

Quote:
"This statement is reported to have brought Einstein, who was walking, to a complete halt in the middle of a busy street."

LOL, I didnt stop in the middle of the street at all. Good for me. Tho not for you may be? What is that. "because at the point of zero volume its negative gravitational energy would precisely cancel out its positive mass energy". " Negative gravitational energy " . Please do enlight me. But i reserve myself the right to judge that affirmation of yours. As you have the right to judge the modern science of physics. What do you consider a "point zero volume"? Are you talking about a singularity here?

[Qev]

As I understand it, it's just a statement that, if the total energy of a system is zero, then under the influence of quantum mechanical effects it's not 'cheating' to have that entire system just pop into existence out of nothing at all. For this to occur, the system in question would have to be small enough for quantum effects to dominate. I assume that by "negative gravitational energy" he means gravitational binding energy?

[JimJast]

Use the quote and edit buttons. To attribute a quote, use quote="name" [...]

I learned how to quote but I still can't find the "edit" button.

[bystander]

I learned how to quote but I still can't find the "edit" button.

While perusing the topic, each post should have a quote button at it''s top right (in the post's header). All of your posts should also have an edit button.

[Doum]

As I understand it, it's just a statement that, if the total energy of a system is zero, then under the influence of quantum mechanical effects it's not 'cheating' to have that entire system just pop into existence out of nothing at all. For this to occur, the system in question would have to be small enough for quantum effects to dominate. I assume that by "negative gravitational energy" he means gravitational binding energy?

I think that this system will have to be the size of the planck lenght or smaller to have the quantum effect to dominate. So it may not become a singularity or it may.
I extract this: Loop quantum gravity theory.
"gravity becomes repulsive at high densities, preventing the formation of singularities. This naturally prevents black holes from collapsing to a point-like object."

From that link:
http://arstechnica.com/science/news/200 ... eality.ars

We still cant measure something the size of the planck lenght or smaller. So is singularity possible or not? As i said earlyer, i am still tempted to consider anything smaller then the planck lenght to be a singularity. So what happen inside something the size of the planck lenght or smaller is impossible to see or measure. That include a singularity or loop quantum gravity or anything. But, as soon as the size of the univers get bigger then the planck lenght, it behave like the big bang theory. Of course the Big Bounce due to the loop quantum theory is also possible but in theory only because we cant verified it experimantaly. I wonder if we will ever be able to find a final answer? LHC may be? Unless the quantum effect of gravity can apply at size bigger then the planck lenght? Uhh it's a story to follow.

[bongman]

The book I mentioned in another post (endless universe) had really made me think hard about our view of a "big bang" singularity begining, the more I read about the Cyclic model the more it makes me say..... "Hmmm"

[apodman]

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The Quote and Edit buttons only appear when you are signed in.

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... we are just right for "light nanosecond" which we are (almost) using but calling it for some reason a "foot".

Most of us remember seeing Rear Admiral Grace Murray Hopper on television. We recall a charming, tiny, white-haired lady in a Navy uniform with a lot of braid, admonishing a class of young Naval officers to remember their nanoseconds. The “nanoseconds” she handed out were lengths of wire, cut to not quite 12 inches in length, equal to the distance traveled by electromagnetic waves along the wire in the space of a nanosecond–one billionth of a second. In teaching efficient programming methods, Rear Admiral Hopper wanted to make sure her students would not waste nanoseconds. Occasionally, to make the demonstration even more powerful, she would bring to class an entire “microsecond”–a coil of wire nearly 1,000 feet long that the rear admiral, herself tough and wiry, would brandish with a sweeping gesture and a steady wrist.

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On the down side, Grace Hopper is the mother of and long-time proponent of COBOL, which is IMHO a horrible programming language that became way too widespread and lingered way too long.

[Chris Peterson]

On the down side, Grace Hopper is the mother of and long-time proponent of COBOL, which is IMHO a horrible programming language that became way too widespread and lingered way too long.

While it's true that COBOL is a horrible language, we've got to keep in mind that compiler theory and language design were both in their infancy back then. So it's not really fair to blame the designer. There's probably plenty of blame to pass around for its long life, however. COBOL is still being used in many applications.

[apodman]

While it's true that COBOL is a horrible language, we've got to keep in mind that compiler theory and language design were both in their infancy back then. So it's not really fair to blame the designer. ...

Oh, I agree, and give great credit, not blame, for COBOL's creation.

... There's probably plenty of blame to pass around for its long life, however. COBOL is still being used in many applications.

Long after object oriented languages came into play, Grace Hopper stubbornly continued to wave the flag for COBOL as the ideal solution to all problems - lobbying for backward progress IMO. I mostly blame the US federal government for making it a hard-to-remove installation in its largest applications, missing opportunities to migrate to something more manageable, and paying the price.

But I didn't mean to get off the subject. I just thought about COBOL and couldn't help myself.

[aristarchusinexile]

G'day from the land of ozzzzz

You can read a thousand papers on time travel, and we all wish it could be so. The reality is that it is not possible. Yes I have read the papers and I can refer many also supporting time travel.

Time is not an item that can be altered changed in any way.

I'm surprised at your firmness of opinion on this, Harry, given your openess of mind. What do you base your opinion on?

[aristarchusinexile]

LOL, I didnt stop in the middle of the street at all. Good for me. Tho not for you may be?

It would be good for me also, Doum, if I were riding my moped in a trajectory which would have impacted you had you stopped, and if my reflexes were hindered in some way, or if my brakes malfunctioned. Yes, I'm happy that we escaped that accident by you not stopping in the middle of the steet I was not riding on. What happens in other dimensions could possibly be determined, and I am working on installing some magnets into my combustion chamber to convert my moped to a 'back to the forwards dimension' machine, and I've added some extra foam rubber to the seat in case the ride gets rocky. As I ride past Phobops I'll be particularly interested in hearing the tune that moon plays as its accordion-like layers are sqeeze and expand at apogee and perigee.

What is that. "because at the point of zero volume its negative gravitational energy would precisely cancel out its positive mass energy". " Negative gravitational energy " . Please do enlight me. But i reserve myself the right to judge that affirmation of yours. As you have the right to judge the modern science of physics. What do you consider a "point zero volume"? Are you talking about a singularity here?

I'm not a physicist .. here is what Wiki says. "Gravitational energy is the energy associated with the gravitational field.
According to classical mechanics, between two or more masses (or other forms of energy-momentum) a gravitational potential energy exists. Conservation of energy requires that this gravitational potential field energy is always negative.[1]
In general relativity gravitational energy is modeled via the Landau-Lifshitz pseudotensor[2] which allows the energy-momentum conservation laws of classical mechanics to be retained. Addition of the matter stress-energy-momentum tensor to the Landau-Lifshitz pseudotensor results in a combined matter plus gravitational energy pseudotensor which has a vanishing divergence. Some people object to this derivation on the grounds that pseudotensors are inappropriate in general relativity, but this treatment only required, in the conservation law, the use of the derivative of the combined pseudotensor which was, in this case, in fact a tensor."

Please, physicists, correct me if I'm wrong; but my current understanding of a singularity is that no matter how tiny it is, it still has volume. " '0' volume would be just that .. no volume whatever.

[aristarchusinexile]

Is our universe, with its big bang, and our 13.7 billion year history , the final death of a black hole/white hole, that big, our universe is but a mere speck inside? could i get some views on this?
http://math.ucr.edu/home/baez/physics/R ... verse.html

when they get the gravitational telescope i feel our eyes, will for the first time, open.
thx
mark

Our eyes are open now .. even for those who cannot see optical light. "I see" said the blind man. Each technological improvement only allows us to see larger mysteries.

[aristarchusinexile]

Dark Matter has been called the new aether.

Not by anybody who understands the nature of science!

We could begin the 'what is the nature of science' debate again, but I will not be drawn into it.

The two examples couldn't be more different.

The two are identical .. both identified by some scientists in their time as realities accounting for observations.

Aether was proposed, without any need or supporting observation, for what would best be described as a philosophical problem: they had a scientifically incorrect belief system they couldn't work around, that a medium was required to carry something. Experiments demonstrated that the aether didn't exist, and better theory eliminated the need for it. Dark matter wasn't proposed in the absence of observation; just the opposite. The effects of dark matter were first observed, and the presence of a form of matter that interacts gravitationally but not electromagnetically was suggested as the best fit. This is precisely the same way that most subatomic particles, including protons, neutrons, and electrons were proposed. None of these types of matter were directly observable at all, only inferred from their indirect effects.

Chris, I will not say Dark Matter does not exist, as at this time there is no proof for its existence or non-existence; but I will propose to you what scientists might say in ten years time concerning the theory of Dark Matter. "Dark matter was proposed, with preconceived ideas labeled supporting observation, for what would best be described as what was at that time an unsolvable problem: they had a scientifically incorrect belief system they couldn't work around, that a medium was required to account for observed effects. Experiments demonstrated that the Dark Matter didn't exist, and better theory eliminated the need for it."

[aristarchusinexile]

you know, they would find it long time ago already, but it's just too f***kin dark and this thread is like from half year ago.

So, Time travel may or not be possible, but it appears it can be bent 360 degrees.

[The Code]

I was speaking Metaforicly for the human race. I have read some of your posts. I was walking to the shop/store, 3 months ago. I live in England, It was dark and very cold plus it was raining. I saw a blind man standing, trying to cross the very busy road/highway. I saw at least 5 people walk past.
I did not walk past, he had stood there trying to cross for 20 minutes and was very distressed.
It took me seconds to help him.

On this forum, I am the blind man, looking for help to cross the busy road/highway. even though i can see perfectly. Some words i do not understand. and some things, that just blow my mind.
But like most people, im looking out of the goldfish bowl. and everything is not as it seems.


help me get my mind round this please.
http://www.physorg.com/news6429.html
in the photo is a light/gamma-ray which is 12,700 million light years old. if our time is constant which i doubt to the extreem. but we could double that, or could we? did it reach the end? because it gave out all is energy in a few minutes? or was it a light from a finite distance? was it another one of those universe things? if there,s one, must there be another? physics tends to make the answer round , everything is round, so the answer is round. or is it the extreem opersite, thats the other thing physics likes to do?

does it go the other way , a gallexy full of universes, with a hundred billion trillion godzilion light years to the next?
help.
now, where was that bone i was looking for?
yours,
mark.

[Doum]

I edit the post i made earlyer. I hope its clearer. Sry for my english but finding the right word is hard.

[harry]

G'day Aris

It is not my opinion, its fact.

Time, Clocks and Causality
http://www.quackgrass.com/time.html#existence

If you want to read other links, just let me know.

Actual time and relative time are two times that people missundestand.

We communicate by radio waves, if you alter the speed or duration of the wave than you alter the communicated time.

[bongman]

Would the local conditions of a supernova be similar or equal to those found at a "big bang"? For the first 10^-43 would the area be domintated with Radiation and Plasma? or are these explosions not thought to be that powerful?

[aristarchusinexile]

G'day Aris

It is not my opinion, its fact.

Time, Clocks and Causality
http://www.quackgrass.com/time.html#existence

If you want to read other links, just let me know.

Actual time and relative time are two times that people missundestand.

We communicate by radio waves, if you alter the speed or duration of the wave than you alter the communicated time.

I'm sure your convinced of your convincement, Harry, and hope you'll enjoy my newly minted word. Personally, I see time as an active participant in the clockwork of our existance, not as something created by man's mind for measurement. I see the possibility of 'time waves' travelling through the universe as easily as gravity waves.
Perhaps it's possible to surf a time wave and stay in the same moment for billions of light years.

[aristarchusinexile]

The article says of Gamma Ray bursts: "It is now widely accepted that the majority of the gamma-ray bursts signal the explosion of very massive, highly evolved stars that collapse into black holes."

That opens the question to me, that if the burst comes from the furthest reaches of the universe currently known, from the first moments, as it were, of creation, how does a highly evolved star form itself in such a brief period of time?
Of course the question can have no answer other than countless possibilities, so it's back to canoeing for me.

[neufer]

Would the local conditions of a supernova be similar or equal to those found at a "big bang"? For the first 10^-43 would the area be domintated with Radiation and Plasma? or are these explosions not thought to be that powerful?

For the first few second the area would be dominated by neutrinos.

It would be interesting to compare the spherical harmonic structure of
the Tycho SNR with
the WMAP background radiation, however.

[Qev]

The GRB in question in the physorg article wasn't coming from 'the first moments'. It occurred when the universe was roughly 900 million years old. Very early, certainly, but not quite the beginning. And more than time enough for stars to form and die.

[Qev]

G'day Aris

It is not my opinion, its fact.

Time, Clocks and Causality
http://www.quackgrass.com/time.html#existence

So, this page is effectively stating that General Relativity is wrong (despite all of it's supporting observations) because Ayn Rand and Aristotle say so? I chuckled at the anti-time-dilation argument that "time doesn't slow down, only certain kinds of clocks do." I'd love to see a proposed design for a clock that wouldn't slow down under time dilation for an external observer.

[aristarchusinexile]

I edit the post i made earlyer. I hope its clearer. Sry for my english but finding the right word is hard.

Doum, where you are from?