MigL

Then again politics, unlike science or math, is based on opinions and I firmly believe everyone is entitled to one as per Voltaire. But obviously someone of the liberal/socialist bent doesn't agree with that judging by the demerit points my opinion earned while yours were merited. Not that I care but isn't tolerance for other's ideas one of your principles ? I know its one of mine no matter what I'm labelled.

Sorry Lizzie but then again my definition of the liberal label is obviously different than yours. By " personal responsibility and valuing hard work ", I;m implying that a lot of left leaning types ( socialist/liberal ) want to live in a nanny state where the government takes care of social and economic engineering, redistributing any wealth gained by your hard work as IT sees fit. If you are responsible for your own actions and value hard work, I don't consider you part of that group and won't label you as such.

I don't understand toastywombat, are you equating a fool with a conservative ? Don' t forget conservative and liberal are just labels and although Phi for All may try to make one label more preferential than the other by assigning the extra label 'progressive' to liberals, I assure you that is not always the case. Many so called liberal policies are actually repressive or even oppressive. Every young person starts off as a socialist and progresses through life becoming liberal and eventually conservative in maturity, as they learn personal responsibility and the value of their hard work. As a result 'I stand by the fact that if I can spend enough time with a liberal, I can change their mind. Direct confrontation never works, plant seeds, keep the dialogue open'. Wise words from a ( hopefully ) wise person, but sadly way off topic.

You can compress water vapour, liquid water and even solid water ( ice ) to varying degrees. Compression waves happen in water, not instantaneously, but at the speed of sound. Ever hear water hammer in pipes ? This question may be better posted in classical physics.

Further to what others have said, you are not just modifying black hole theory but also established nuclear physics, stellar evolution theory and general relativity. Your burden of proof increases exponentially with each added conflict with established theory.

Sorry Michel123456, I was leaving from work this morning and in a rush ( it snowed AGAIN last nite ) and I replaced one too specific example with another. Let me see if I can clear it up. Bound states, with few exceptions are lower energy states than unbounded states. In the case of gravitationally bound clumps of mass within a common gravitational well, the bound state is lower energy than the unbounded, i.e. you need to add energy to separate the masses as on their own they will tend to come together. In the case of viscous liquids bound together by surface tension the lowest energy state is that which binds the liquid in a spherical configuration and again energy has to be added to break it apart. In the case of electromagnetically bound atoms where the electrons are bound by Coulomb interaction to the nuclear protons, the bound state is again the lower energy state and energy ( ionizing ) has to be added to separate them. In the case of residual electromagnetic bounds between molecules ( van Der Waals ), again the bound state is lower energy, and usually heat helps to decompose these molecules. The few exceptions, which I include because I know you'll bring them up, are such as unstable large nuclei which fission, and self heating or deflagrating chemicals where a little energy added to the stable bound state, changes it to an unstable state ( but maybe John C. can clarify this more as I'm not very familiar with explosives and organic oxidisers ).

You took my example a little too literally Michel123456. OK, take a REALLY big rock, say in space, and swing a HUGE sledgehammer ( Nuclear bomb ) at it. You have added energy and the rock breaks up. You now leave to its own and see the pieces come back together gravitationally to its lowest energy state, as near as it can get to spherical. No energy added !!! You won't see a regular rock do this because of the entropy of irreversible processes. So you have to expend more energy to physically bring the pieces back togrther

The only way to seriously look at it is to consider elementary particles like two electrons, They have equal masses and equal charges and since they are elementary, there is no 'empty space' in them. Gravity will tend to pull them together while their charge will tend to separate them. I haven't looked it up in along time, but off the top of my head, I seem to remember the separating force is 10^18 times stronger than the attractive force. I.E. you will never form a black hole of similarily charged particles.

Might be simpler to look at it fron a physics point of view... A rock has a given amount of energy. You need to give it more energy ( in the form of a swinging sledgehammer ) to pulverise it. Ergo the solid rock has less energy than the rock debris.

As always AJB, thanks for your insight and an interesting discussion.

I agree AJB. But I consider geometry a dimensional arrangement, of the three spatial plus time for GR. We can consider the classic EM field. Being conserved and long range means we can assign a value to this field at every point in space-time such as V so that every point is described by (XYZTV). GR then gives us a new metric and curvature as per Kaluza-Klein theory. We note however that to get to QED, it is not the geometry of the EM field which is quantised but the actual field Loop Quantum Gravity attempts the same thing with GR. It does not quantise the geometry, rather it removes space-time from its background position and moves it foreward ( no background ) as the equivalent to the field and then quantises it ( with certain nuances ). In effect space-time is the field.

Just to add to swansont's answer to the sixth question ... Yes we look into the past all the time as all light travels at a finite speed to our eyes. Our telescopes look billions of years into the past at faraway galaxies. So yes it is 'a form of time travel, or rather seeing the position of objects/forms in the past through photons', no prediction needed.

Thanks a lot AJB, you crushed all my arguments. But seriously, my personal preference is to think of GR as a geometric model as I-try also explained in post #29. I realise one could consider the geometry of space-time a field, but think that would be stretching it. Just my opinion since I don't have to do the math like you do.

What about the other point I brought up about action at a distance? For the classical field model of gravity |( Newtonian ? ), one test mass has to transfer information to another test mass so as to draw it nearer, i.e. gravitate. One can make the argument that sometimes it has to transfer the information superluminally when great distances are involved. For the GR ( also classical ) geometric model, the test mass transfers information to the space-time manifold and 'curves' it beforehand. The second test mass then receives the already existing information from the space-time manifold and adjusts its path accordingly. A subtle difference but certainly non trivial.

So the geometry is a field ? Now that would be semantics. Wasn't one of the reasons for GR the elimination of "action at a distance" so abhorred by Einstein ? And to get to a quantum gravity field theory you'd have to quantise the geometry ?

As AJB has explaned gravitons are a feature of quantum gravity fields. GR on the other hand is NOT a quantum , or any kind of, field theory. It is a geometric theory of gravity, Unity+.

Hey I'm still here !! But seriously, it is not crackish but accepted physics and a little understanding of GR will make it clear. But you are right, I wrongly attributed Kevin D's post #6 to you. I apologise profusely.

What I mean is that a free falling object, i.e. in a gravitational field, such as Timo's cup, has no forces acting on it according to GR. The ground, or a table, stops this free fall by exerting a force on the cup. That's not semantics. So what part of my statement would not be clearer with an understanding of GR Timo ? Please elaborate.

Funny how apologists like AtomicMaster are always quick to blame their own and claim the other guys are the oppressed. These so called Crimean pro-Russian forces are better equipped than the Ukrainian armed forces. But of course they're not Russian troops ?!?! Don't get me wrong, Obama and the EU are not blameless, having endless meetings and discussions ( hand-wringing ) while the Russians acted. But if the Europeans had any nads, as soon as the Russians announced the referendum for Crimean independence from Ukraine or annexation by Russia, the Europeans and NATO should have announced their own referendum for all of Ukraine as to whether they wanted to join NATO to be held one week prior. I don't think Vladimir would have been so bold then. He's not protecting Russian speaking peoples but securing access to the Mediterranean through the Black sea ports of the Crimea. All the British, French , Italian, Turkish and German ( ? ) that died for the same reason in 1850 did so for nothing as we haven't learned anything from their sacrifices.

Just what it says. And if you have trouble understanding that, read up on GR theory, as that will also help alleviate some of your frustrations. Don't mean to be a knob, and maybe I misunderstood your post, but GR tells us that the 'cause' of gravity is space-time curvature. Unfortunately it doesn't tell us why mass-energy causes space-time to curve. Or is this just an explanation gained by moving the goal-posts in your mind ?

The event horizon and ( possible ) singularity are different Enthalpy. The much larger horizon 'cloaks' the singularity from the rest of the universe. As far as I know naked singularities are a no-no, and primordial microscopic horizon ( small mass ) black holes should have evaporated long ago due to Hawking radiation. But who knows, we may be able to create microscopic black holes using a large enough accelerator. The LHC is obviously too small.

What exactly have you added to this discussion other than voicing your frustration at not understanding that nothing 'holds us down' ? In effect the surface of the Earth holds us UP !!

Enrico Fermi, probably the last physicist able to excel at both theoretical as well as experimental physics.

I'll have to have a read through that section of Gravitation ( M/T/W ) and see if it clarifies anything for me md65536. Didn;t realise it had material on gravity waves.

If we consider gravity a field, then quantum field theory dictates there exists a boson excitation that 'carries' this field. We call this boson a graviton and it arises in any quantum interpretation of gravity. The general relativistic classical interpretation does not invoke quantum field theory and therefore has no use for a graviton. Gravity is solely based on space-time curvature and could even be considered fictitious, i.e. two parallel lines on a positively curved surface will tend to come together as if attracted to each other by a force ( however all fictitious forces that I know of are frame dependant, and there is no alternate frame for space-time curvature ).