MigL

Also your definition of an active galaxy is not accurate. Active implies that the central black hole is injesting a lot of stellar matter and interstellar gas, has a sizeable accretion disc, and produces polar jets. The Milky way and Andromeda have centres which are x-ray sources ( that is the method for detecting the massive core black hole ), but certainly not strong enough to indicate that the core is active and injesting stars.

Theories are modelled mathematically Desmond. There is no ambiguity about mathematical meaning, at least if you have a PhD and undestand the math, as there is with words. Arguing about meaning and context of the words 'nothing' and 'from' may seem common sense to you, but it is not.

OK David Levy, since you won't answer ACG52's post, let me ask you. By what mechanism does the generation of matter at the galactic centre affect our sun 26000 lyrs away ?? Sorry I couldn't resist.

If the Higgs mechanism is the 'cause' of mass, then there needs to have been a spontaneous symmetry breaking. Possibly the same symmetry break which was the beginning of the inflationary period as the vacuum settled to its true ( ? ) zero energy level. In effect, prior to inflation there may have been no mass as we know it and no singularity.

Well the best authority that I've known on relativity, DrRocket ( apparently not on this forum anymore ), says relativity is not on your side as ALL events, past, present and future, exist in space-time. GR is of course, deterministic, so this needs to be taken with a grain of salt, but you certainly cannot argue that just the 'present' foliation ( 3 dimensional ) is all that exists. As for your mention of Einstein, it was he who is most responsible for showing that only past events affect us due to the constant and finite speed of light, the present certainly cannot affect us at any measurable separation. Incidentally are fossil records, old books, etc. almost 'completely subjective' ? I would argue that the past exists through causality. If the past is a figment of our collective imaginations, what causes events to happen in the present ? The causality argument can then also be extended to the future, which again needs to be taken with a grain of salt since certain aspects of QM allow for violation of causality.

Severian, the SU(5) symmetry model is the simplest such model, and has the strong force 'breaking away' at 10^15 GeV, and the electrowek 'break-up' at 250 GeV, leaving symmetry groups which you've already mentioned. However, the SU(5) model also predicts proton decay after 10^32 yrs. All current experiments have failed to find a single result of proton decay, and have estabilished a lower limit on a proton's half-life which is several orders of magnitude higher than 10^32 ( don't recall exact min. half-life, you'll have to look it up ). I don't have much exposure to group theory, so unfortunately the SU(5) model is the only one which I can hope to make some sense of. Maybe some of the others can elaborate on other GUT models.

I know a little of the interaction as it pertains to electroweak symmetry breaking, AJB seems to be the resident expert, but maybe Aethelwulf will write up something for us. In the above mentioned gauge theory, the spontaneous symmetry breaking creates, from the Higgs field, Goldstone bosons which interact with the formerly massless +/-W and Z gauge bosons to give mass. The Higgs field has been compared to an 'inertial drag', but it is not that simple, there is an interaction involved. And no, I don't do laTEX, so we'll have to wait for Aethelwulf.

It is my understanding that half-integer spin fermions acting in pairs can imitate integer spin bosons. Superconductivity theory is based on this effect. I would think BEC can consist of paired fermions.

Higgs' field is a scalar field, see PMB's definition of a scalar field in one of his previous posts. That being said, QFT dictates that there are field 'excitations' we call Higgs bosons. The only connection between fields ( of infinite extent ) and dimensionality is that field intensity ( strength ) drops off with r^(n-1) where n is the number of spatial dimensions. This has some interesting effects on gravity in 10D ( spatial ) M theory.

That equation you spoke of (49) is merelyl the acceleration in terms of the equation of state. The third line below that states "But we have seen that a cosmological constant has the odd property of negative pressure, w=-1,so that a universe dominated by vacuum energy actually expands faster and faster with time" Now negative gravity might not be a 'professional' term but what should I be using , repulsion, anti-gravity, expansion, inflation ??? The fact remains that a negative vacuum pressure which is over a certain threshold, will ovecome the normal gravitational attraction, and actually start 'expanding' space-time like the cosmological constant and inflation do. Someone once said if you can't explain something in simple terms, the you don't understand it. So let me know how I do. Consider a spring and put pressure on it. This usually compresses the spring but we'll disregard this effect. The pressurised spring has more energy, and if you were willing to do an accurate enough calculation you would find that it actually weighs a miniscule amount more it will, in effect, have a slightly greater effect on the space-time curvature around it and therefore a stronger gravitational well. If you then remove pressure from the spring, you are actually removing energy from the system with the resultant less space-time curvature and less gravity. Now consider the vacuum, it has the same compressibility as the spring with the exception that negative pressure on the spring actually stretches it and again gives it more energy. The vacuum instead, can have more and more negative pressure and keep losing more and more energy. Since the system in this case is not the spring but the vacuum of all space-time, it is all space-time whose energy is becoming more and more negative. If I remember correctly from one of DrR admonishments, GR does not have the condition of conservation of mass-energy ( during a discusiion of Noether's theorem).

Sorry Timo, I went back and realised my mistake. The phrase "In GR it can be shown that a high pressure condition results in a negative energy/gravity condition" should have read as "In GR it can be shown that a high negative pressure condition results in a negative energy/gravity condition". It needs to be highly negative pressure because it needs to overcome gravitational attraction before it can start acting like a Cosmological constant or a cause for inflation. The same Kinney lecture notes have a brief explanation of this at the beginning of section 2,5, pg 15.

Have that reference for you now Timo. Abook called COSMOLOGY, INFLATION AND the PHYSICS of NOTHING by William H Kinney of the department of strings, physics and cosmology at Columbia university. I believe section 2.4 ( pg 13 ) The Vacuum In Quantum Field Theory deals with vacuum energy calculations and the relation between pressure and gravity is explored in another section ( sorry did not look that one up ). An interesting book if you have access to it ( I have an e-book ).

This is all rather speculative Timo, but the same vacuum energy which produced inflation shortly after the big bang obviously has a residual presence. We can call it 'dark energy' or a Cosmological constant, but some kind of 'negative' gravity is not only keeping expansion going, it is accelerating it. In GR it can be shown that a high pressure condition results in a negative energy/gravity condition. If I recall Guth's original inflation theory used a false vacuum energy condition due to symmetry breaking of a scalar ( Higgs ? ) field, but that has since been shown not to be the case. In any case it all depends on getting a handle on the value of the vacuum energy, which as I said earlier, is way too high. As to which and who's guesstimates, sorry but I'm passing the time at work and don't have references ready, I usually post retained info from various books I've read.

Arguments can be made for the total energy of the universe to be zero since the universe is expanding. By no means are these guesstimates accurate enough to say one way or the other. The biggest question mark is vacuum energy. A simple 'back of an envelope' calculation using simple harmonic oscillators and using the Planck scale as the cut-off yields a value which is 120 orders of magnitude higher than expected.

OK Juan you got me, that is what I wrote. But I get the impression that you know exactly what I actually meant to say, you just seem to thrive on confrontation. As a matter of fact the first part of the Feynman quote you posted alludes to exactly the behaviour that I talked about in my original post to which you took exception. Notice also that I did not say anything about the cause or explanation of said behaviour. But I will agree with you on that matter, QED does provide a fuller and more consistant explanation than wave theory does. I have also mentioned that fact in a previous post. So tell me again, what exactly are you going on about ??

Ok juan, sorry I'm a little dense sometimes. Thanks for the clarification.

Don't put words in my posts Juan, I did not say a wave is detected. What I said was that an experiment to detect wave behaviour will get the usual interference pattern on the screen, ie wave behaviour is manifested. Particle behaviour is also manifested in other cases, but I've never said electrons are both particles and waves as you imply I've said. As a matter of fact I was one of the first to state that wave and particle behaviour are mathematical models which don't describe the actual reality, ie electrons may be neither. We have one group touching the trunk of an elephant and saying its snakelike and another group holding the elephant's ear and saying its thin, flat and floppy. The elephant is neither, but it does exibit those qualities.

Basically the time machine aspect involves using two wormhole generators. I have one in my spaceship and Kip has one in his house. We use them to open a wormhole between our two locations so we can see and talk to each other through the wormhole. I then take off at relativistic speeds to another solar system, get there, look around and come back to earth, all the while talking to Kip. When I land on earth I realise 1000 yrs have elapsed since I began my journey ( special relativity effects and all that ), But I'm still talking to Kip, now 1000 yrs in the past. "No problem" he says " Just step through the wormhole". So I do, and am now 1000 yrs in the past. Voila' a time machine. I told you I'd be wrong again ACG52 ( about the book ), but at least I still have mine.

Sorry Juan but I don't see the significance of your link, it doesn't negate anything I've said. Light is affected by gravity because its energy is equivalent to mass. The zero 'rest mass' of a massless particle is a defined concept because massless particles only travel at c ( no matter what Granpa says ). They can never be at rest. Oh no !! Now you've got me arguing about the definition of mass !

Since Juanrga is more interested in discussing terminology and definitions, let me try to answer your question MrMuse. Quantum Mechanichs is very dependant on observation for the result. In the typical double slit experiment, an electron or similar particle ( ? ) is emitted on one side and allowed to pass through to the other side. Now if the observer sets up an experiment to detect particles, he will be able to determine which slit the electron passed through. If he sets up an experiment to detect waves, he will see the usual interference pattern from interfering wave fronts. What is even stranger is that the observer can wait until the electron has already passed through the slit (s) before deciding which experiment ( particle or wave ) to perform, and the results will still be the same. I forget the name of this experiment, delayed choice or something like it, but it has all sorts of strange implications,

Kip Thorne was a student of J A Wheeler, and along with Wheeler and Misner co-authored the definitive book on gravity and GR called Gravitation. He is one of the leading experts on black holes ( in my mind ) along with Hawking and Penrose. He did some work on time travel but was afraid of not being taken seriously so he coyned the term Closed Timelike Loops. I would imagine he has the greatest respect for Einstein and his ideas, which are accurately explained in this book. I have the book, both paper and e-book and I could have sworn its 'space warps' not 'time warps', ACG52, but I've been wrong before and I'm sure I will be again.

PMB and Juanrga can you guys stop arguing for a moment about the definition of matter ? Who really cares ? Space-time affects mass-energy and compels it to follow its curvature, so yes photons and anything else with mass ( and don't start arguing about mass definitions either ) is affected by gravity. Spyman lightspeed is c in all frames, strongly gravitating or not, even a far-off observer. Keep in mind that that speed is measured by arriving light signals which give distances travelled per unit time. Even light coming out of a black hole's event horizon is moving at c, although you'd never know it since it is red-shifted out of existence ( infinite wavelength and zero frequency ) upon escaping the event horizon. As for Sanford, I think he has alot of misconceptions about the validity of GR inside the event horizon. It is only at very close distances to the possible singularity that GR must be modified by quantum effects. It is not meaningless to speak of the interior of the event horizon as time most certainly does not stop if you keep your frames straight.

I don't know, from your posts it seems that you are and you do ... But seriously, no-one will mistake you for Robert L. Foreward, the author of Dragon's Egg. Instead of getting your information from TV shows like Star Trek: DS9 go to your nearest library and check-out a book by Kip Thorne called Black Holes and Space Warps; Einstein's Outrageous Legacy. It is a very understandable popularization and has a section on wormholes and their uses as modes of transport through space and time, along with the required exotic material ( negative energy material harvested on the edge of a black hole's event horizon ) needed to keep them open for an appreciable length of time.

And what physical reality do 'quantum particles' represent ?? I'm not saying you are wrong, I just don't think its fair to say that one is more 'realistic' than the other. They are both mathematical models of a reality which may actually be neither . What you should say is that one has a more complete mathematical model than the other, but then again most applied quantum mechanics is not done with QED, but rather good, old-fashioned wave mechanics.

Not exactly accurate. While a plane trip does slow down subjective time for the traveller because of relativistic time dilation, there is some compensation since planes usually travel at 36000 ft. In effect, we left behind on the ground, experience gravitational time dilation compared to the traveller since we are deeper in the earth's gravity well. As for time travel, I have to admit that I cannot disprove it, yet my 'gut' tells me that its impossible. Causality may be violated in certain quantum processes just as process flow is valid foreward or backwards and even entropy is not constrained to stay equal or increase. But for statistically larger systems, entropy always stays the same or increases, processes only make sense in the foreward direction and causality cannot be violated