MigL

If Andrew Wiles answered it here with the 300 pages of proof I can guarantee you no-one would ever read all of it. ( just kidding ) I agree with sensei and John also. Some indication would be good.

I beg to differ John. Just asking the question degrades the discussion of 'ideas'. That is the problem with labeling "ideas' as liberal/conservative/enlightened/progressive/insane/etc. And no, I'm not offended, Imatfaal, I just expect better in an intelligent discussion.

Furthering knowledge is never a bad thing. If you can handle the workload, by all means, do a combined major. Myself, however, I tend to side with Mr.Skeptic for all the excellent reasons he cited.

The first time you answer the door in your underwear, AJB, is the last time you'll ever see those 'smartly dressed people'. Guaranteed !

Darn weather ! Snow up to my knees from the last snowstorm, and its snowing again. Where is Global Warming when you need it ! ( just kidding )

Life is far from fair. My only advice would be " go west young man ". I and my family immigrated to Canada from Italy. My dad used to work in Switzerland and I saw him in the summer and Christmas time. Both me and my brother have university degrees, and his son ( I have no kids, never married ) recently finished his Masters in Biology, obtained his teaching certification and works for an engineering firm doing Environmental Assessments. Canada has provided, and continues to provide, opportunities which may or may not have been available to us in Italy.

No, I believe I said there is less thrust needed to keep the airfoil 'in place' ( only horizontally ) when it is allowed to rise, than to keep it 'in place' ( horizontally and vertically ) when it is not. In effect, the air loses less kinetic energy if the airfoil is allowed to rise than if it is not., Consider a fan ( vertical airfoils ). If it is stationary it imparts all its rotational energy to the airstream and accelerates it. If it is allowed to move, like a propeller, it imparts a lot less energy to the airstream, but rather 'screws' through the air.

All the trouble spots in the middle east are ruled by religious leaders or have a disproportionally large religious influence in their governance. Religion is open to interpretation by fanatics. The problems will only stop when secularism and democratic processes are adopted, OR when they are shown that we have the resolve to protect what is important to us ( as Truman did ). Remember when the pope was the effective ruler of the empires of Europe ? How many people were burned at the stake in the late middle ages ? How many were stoned to death ? You could be killed with impunity for looking at an aristocrat/prince/emperor the wrong way.. This is where a lot of the middle east is today.

Oh come-on, now its just silly. By 'labelling' the other side of the argument as mad or insane, you are just trying to lower the value of that argument without having to do the 'heavy lifting' of proving that argument to be invalid. No-one with any intelligence/integrity minds if their opinion is proved wrong with facts. No-one likes their opinion to be discounted simply because of a label.

But the claim that the CHILD is better off when the father marries the mother is certainly accurate. And not for religious reasons either. And you can't claim that the Bible is fiction when it says the earth is 6000 yrs old, and truthful when it claims Jesus had a 3 parent family. This is a science forum, so let's all agree that it is fiction with possible, real historical figures, meant to guide us and teach us morals. And further, those morals apply to a previous age ( almost two millennia ago ), and some may no longer be relevant

I remember vector graphic video arcade games in the late 70s, early 80s. Don't remember the name of the game ( was it 'Asteroids' ), all you did was shoot up asteroids, but you triangular spaceship could fly off one side of the screen and re-appear on the other. Maybe I should have spent more time on my hi-school/university studies. Good times though.

Although studiot has attempted to explain things very clearly, I get the impression we need to simplify the thought experiment further. Get in your car and drive on a highway at 100km/hr. Now roll down the window ( wait till summer ) and stick your arm out such that your hand makes a 30 deg. angle of incidence to the direction of travel. We can look at the situation as either your hand moving through the air or the air moving past your stationary hand, it doesn't matter which. You will note that you feel two components of force on your hand, a large component pushing your hand backwards ( drag ) and a smaller component pushing your hand upwards ( lift ), and to keep your hand 'stationary' in the frame of the window, you have to exert considerable force down and forward or your hand will go flying back and up. This is the thrust or motive energy you must provide to keep your crude 'airfoil' hand 'stationary' ( at 100 km/hr ) in the frame of the window. However, if you let your hand rise in the vertical direction, you do not have to supply the downward thrust or push to keep your hand vertically stationary, just the forward component of thrust. Now since moving hand/stationary air is perfectly equivalent to stationary hand/moving air, we can look at the forces the air applies to the stationary hand and the hand that is allowed to rise. Similar ly to the previous case the air applies less force to the hand if the hand is allowed to rise. In effect, the air doesn't have to push upwards and loses less energy ( it is deflected less ) than the vertically constrained case..

The peltier effect is just a semiconductor heat pump. It will take heat away from one section and move it to another. So which part of the earth were you intending to freeze, and which part were you intending to roast ? you can't escape the laws of physics !

A 'hard surface which would prevent an object falling any further' ? That could be an assumption made by a faraway observer, but in the frame of the infalling observer, what could possibly keep this 'hard surface' suspended ? It would need to be moving outward faster than the speed of light.

I see your point swansont, but I would still expect energy to be conserved globally, even without GR being able to confirm it. The alternative opens up a 'can of worms'.

This is all fine and dandy. We now have various explanations of the workings, history and etymology of geodesics. But I believe the OP was along the lines of ' is gravity a force ? '. I see very little discussion as to whether gravity is an 'action at a distance' force mediated by force carrier bosons ( gravitons ? ), or, a particular arrangement of space-time such that mass ( and energy ) is constrained to move along the resultant geodesics.

Off the top of my head ( 3rd yr semiconductor physics and 4th yr solid state physics were a looong time ago ), the effective mass is the 'apparent' mass that a particle seems to have as it makes its way through a crystal lattice. This effective mass being 'heavier' for denser or more tightly bound crystals. So what I dimly remember jives with what I said. I expect you'll now set me straight.

Ah, but classically there is no matter left inside the BH for the virtual particle to annihilate with.

Negative energy or negative mass is an 'accounting' trick, possibly without a 'real' consequence. Two virtual particles pop into existence at the event horizon of a black hole. One falls iside the event horizon. Its partner flies off and becomes real ( hawking radiation ). The other particle is the 'interesting' one. It falls into the black hole, yet the black hole loses mass ! This is termed 'exotic' matter, and it has the property of 'negative' mass/energy. Whether this has an actual physical meaning is debatable.

I remember solving the Helium atom in 3rd or 4th year, using numerical methods. Using Hollerith punch cards and a Burrows B6700 mainframe computer ( room sized ). Only took about a week.

I always thought GR doesn't say anything about conservation of energy. Is this a 'shortcoming' of GR ? Or is energy conservation not a valid global concept ?

Don't want to wade into studiot's and Strange's discussion, but as for the OP... Syncronization is equivalent to simultaneity. So just like simultaneity it is not valid across frames . Things can only be syncronized within a frame.

Just got back to this crummy weather in Canada.. Yes, the answer to your question is more drag. There is a difference between bouyant ptential energy and gravitational potential energy. An object less dense than the surrounding fluid experiences an upward force, its potential is highest at sea level and decreases as the density of the surrounding fluid decreases with altitude. Gravitational potential is, by definition, due to a downward force and is highest at infinity ( gravity is a long range force ) decreasing a as you approach the ground. A bouyant force causes unconstrained motion upwards while gravity, if unsupported, causes you to fall down. At any height the two potentials subtract suchb that the NET potential causes unconstrained movement in the direction of lesser net potential. Studiot is a technical writer so, i suppose, he demands extreme accuracy in his wording. Myself, I'm not so strict.

Should we re-examine my use of physics ? Or my use of language ?

Sorry, I see we must use our words carefully. Yes John is right, the demagnetized state is not a higher energy state than the magnetized state. But yes, energy must be supplied to 'quickly' randomize the domains. Natural demagnetization occurs slowly ( unless you're talking about the collapsing field of an electromagnet ) and the energy is 'lost' since it becomes entropic. There are only two ways to arrange the magnetic domains in a bar magnet while the domains of a nonmagnetic piece of iron can be arranged myriad ways. I.e. higher entropy.