Re: How does gravity work?
Posted: Sun Feb 26, 2017 11:34 pm
Feynman. But you're still 0 for 12 or so on substance.wtf wrote:Thanks Weiman.Wyman wrote:I remember watching a video of a Feinman lecture ...
For the discussion of all things philosophical, especially articles in the magazine Philosophy Now.
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Feynman. But you're still 0 for 12 or so on substance.wtf wrote:Thanks Weiman.Wyman wrote:I remember watching a video of a Feinman lecture ...
Actually, on reflection, it is fairly clear who you were addressing, so I'm sorry I didn't read with more care.Wyman wrote:My comment was directed at the other guy - wtf. Sorry I wasn't clear.
This relates to what I said about general relativity above. Einstein did a lot of his best work by exploring the consequences of thought experiments. For example one of the questions he asked was if you were travelling at the speed of light, and you held a mirror in front of you, what would happen to your reflection? Intuitively the answer is that it would disappear, because the light couldn't reach the mirror to be reflected. Einstein didn't like that idea, so he slowed down time, squeezed space together and came up with special relativity. A lot of the mathematical modelling had been done a few years earlier by Hendrik Lorentz and the mathematical model of 4D spacetime was developed by Herman Minkowski.Wyman wrote:I have a question. You talk of a mathematical model of a physical model of the universe. Why two models? Why not just a mathematical model?
The idea that time is a substance that can be slowed down, or that space can be stretched or warped are psychological tools that help make sense of the maths, but the fact that the maths is so successful leads some physicists to believe their psychological tools are real, much as people believed the experimentally successful Ptolemaic geocentric universe was real. The fact is, you can make up any psychological tool you like that is consistent with the maths, so there could be several physical models that will do.Wyman wrote:I remember watching a video of a Feinman lecture about models. He presented two models of gravity in which the maths were the same. He basically said that the physical models were merely psychological tools for solving problems.
Wyman wrote:He distinguished two philosophies towards models - the Greek, which is deductive; and the Babylonian, which is ad hoc - bits of model here and there, changing from one to another as the need arises. He advocated for the latter, claiming the Greek philosophy is artificially limiting.
Richard Feynman is always worth watching.Wyman wrote:Interesting lecture, it's on youtube.
Gravity exists because of the Higgs field.uwot wrote: How does gravity work?
Is that a fact about the universe? Or a fact about the model? Since our idea of gravity has gone from Aristotle to Newton to Einstein to Higgs, why shouldn't there be an even better idea next century?attofishpi wrote:
Gravity exists because of the Higgs field.
So is there "really" a Higgs field? Well, there turned out NOT to be an invisible Newtonian force acting at a distance. What makes us think there is a Higgs field; as opposed to the Higgs field being merely the name of the latest mathematical model that works, along with a convenient visualization? A field like the magnetic field that we can see when we pour little grains of metal on a piece of paper with a magnet underneath it like they showed us in school? Is there really a field? What is it, exactly, and why? It's bowling balls on rubber sheets again. Stories we tell ourselves to help us visualize the latest mathematical formalism that fits the experiments.uwot wrote: The idea that time is a substance that can be slowed down, or that space can be stretched or warped are psychological tools that help make sense of the maths, but the fact that the maths is so successful leads some physicists to believe their psychological tools are real, much as people believed the experimentally successful Ptolemaic geocentric universe was real. The fact is, you can make up any psychological tool you like that is consistent with the maths, so there could be several physical models that will do.
So to answer your question, the mathematical model is all you need to do physics and to some physicists, physical models are just philosophy.
As i stated earlier, i watched Sean M. Carrol explain the recently proven higgs particle.wtf wrote:Is that a fact about the universe? Or a fact about the model? Since our idea of gravity has gone from Aristotle to Newton to Einstein to Higgs, why shouldn't there be an even better idea next century?attofishpi wrote:
Gravity exists because of the Higgs field.
A statement like "Gravity exists because of the Higgs field" seems to me to confuse the map with the territory.
Suppose you had been living in the time of Newton, and you attended a brilliant lecture describing gravity as an invisible force between massive objects. Would you say, "But it seems that at these sub atomic scales, that yes there is a force -- the Newtonian force -- that DOES cause matter to attract other matter in proportion to the product of their masses and inversely proportional to their distance."attofishpi wrote:
I've been trying to find the video, if i do i will post it. But it seems that at these sub atomic scales, that yes there is a field - the Higgs field that causes SOME of these sub atom particles to be susceptible to mass, hence gravity.
Lots and lots of questions here. I think that when talking about the Newtonian model of gravity Newton gave us a great understanding of how mass and distance played in effect of their relative distances when it comes to objects we can hold and throw and bounce.wtf wrote:Suppose you had been living in the time of Newton, and you attended a brilliant lecture describing gravity as an invisible force between massive objects. Would you say, "But it seems that at these sub atomic scales, that yes there is a force -- the Newtonian force -- that DOES cause matter to attract other matter in proportion to the product of their masses and inversely proportional to their distance."attofishpi wrote:
I've been trying to find the video, if i do i will post it. But it seems that at these sub atomic scales, that yes there is a field - the Higgs field that causes SOME of these sub atom particles to be susceptible to mass, hence gravity.
Would you say that? Or, with the hindsight we have today, would you recognize that as a description of a MODEL of reality but not ultimate reality itself?
If the latter, can you see that a hundred or five hundred years from now we'll see the Higgs the same way? As a great approximation for its time, but not literally true?
Can you see that? Or do you think that this year, of all the years in human history, we are in possession of the ultimate truth about gravity?
Now we're getting somewhere. Me too. My only point is that ALL science is model building and so far we have never gotten to "ultimate" reality. If we imagine ourselves a hundred or five hundred years from now, it's likely that our current theories will be seen as no more than the best approximation we were capable of.attofishpi wrote: And to add - no im not sure the Higgs is the ultimate truth to gravity - im just a laymen who the fuck am i to make such a decision!!
This was a pivotal moment in history and, more than any other, marks the separation of physics and philosophy. What you would have heard in a brilliant lecture on gravity, would have depended on which side of the English Channel you had been. In Britain you would probably have been listening to a Newtonian explaining the inverse square law, a strictly mathematical description. Had you stuck up your hand and asked how it actually works, the answer would have been, effectively, don't know, don't care. On the continent, it is more likely that you would have been listening to a Cartesian, Gottfried Leibniz for example, giving an account of the vortex theory of gravity, according to which space is made of tiny bits of matter which are swept around the sun, a bit like water going down the plughole, with the Earth as a rubber duck being dragged around with it.wtf wrote:Suppose you had been living in the time of Newton, and you attended a brilliant lecture describing gravity as an invisible force between massive objects. Would you say, "But it seems that at these sub atomic scales, that yes there is a force -- the Newtonian force -- that DOES cause matter to attract other matter in proportion to the product of their masses and inversely proportional to their distance."
The Higgs field is, in effect, a refinement of the vortex hypothesis, at least insofar as it is a philosophical account of what creates mass; which as Noax alludes to, in this instance is synonymous with inertia. Basically, the Higgs field is some hypothetical 'stuff' with mechanical properties. What makes it physics is that there is a mathematical treatment which predicts that if you hit the field hard enough, you will create a ripple with specific properties called the Higgs boson. What the LHC has discovered is a ripple that looks very like the one predicted. There is no reason to think that in 500 years time, smashing hadrons together won't produce the same ripples. Whether our descendants attribute it to the Higgs field is a different matter.wtf wrote:Would you say that? Or, with the hindsight we have today, would you recognize that as a description of a MODEL of reality but not ultimate reality itself?
If the latter, can you see that a hundred or five hundred years from now we'll see the Higgs the same way? As a great approximation for its time, but not literally true?
Well, then you get into underdetermination. We might actually be in possession of the ultimate truth, but there is no way of knowing what future experiments will uncover.wtf wrote:Can you see that? Or do you think that this year, of all the years in human history, we are in possession of the ultimate truth about gravity?
I have you at a disadvantage uwot, because I was flyer. All that I wrote above was not something from a book that I referenced yesterday. It was from the memory of my training in 1975 & 1982 and my subsequent 2000 hours of flying aboard a Lockheed Orion P3-C as an Aviation Antisubmarine Warfare Equipment Operator where I talked daily with pilots in the cockpit, even being allowed to control the multi-million dollar beast of a bird for a moment or two. For 14 years I worked in, on, and around, multimillion dollar aircraft. One of the aspects of my job was considered, "safety of flight." At least my pilots loved me, though I couldn't say that of my tacco, (I was better at flying than killing) .uwot wrote:Absolutely true, but will an aeroplane take off if it doesn't divert a whole load of air downwards by lifting it's nose?SpheresOfBalance wrote:Lift is created because of the air foil design...
Just wanted to mention that this doesn't give you as much credibility as you'd think.SpheresOfBalance wrote: I have you at a disadvantage uwot, because I was flyer.
This statement is a violation of Newton's third law. Something must be pushed down to drive a heavier-than-air object aloft. Nose tilts up, the wing angle of attack pushes air down the same way it does with a ceiling fan. In level flight, there is a net downward thrust to the air which is planely (pun intended obviously) evident if the aircraft is flying through a medium (100% humid air for instance) in which its wake becomes visible.SpheresOfBalance wrote:The wing is not pushing air down, the air is pushing the wing up.
GTR works quite well, but it cannot explain "dark" matter and it cannot be quantized. And for example such shift of Mercury trace has been exactly (the same expression) computed by clasical way by, I think, Paul Gerber...uwot wrote: ↑Sat Feb 25, 2017 9:03 pmI think you mean test. Well, the detection of gravity waves by LIGO is one.Cerveny wrote:- Can you name any (model)?It's not that GR doesn't work with gravitational repulsion necessarily, there is clearly a phenomenon that is not predicted the theory. Nonetheless, GR still works very well on the scale that we can measure it under controlled conditions.Cerveny wrote:- I only critize that GTR does not work with gravitational repulsion.Fair enough.Cerveny wrote:I do not compare dark matter with antimatter.
There is no reason to expect the universe to conform to human logic, however it is reasonable to expect human logic to conform to the universe or what is observed.
Well logic is a set of rules for language, and you are quite right, there is no reason to expect nature to behave in the same way as words.
I'll defer to any logicians on this one, it's not my field, but as I understand it, there are various types of fuzzy logic, that attempt to take account of the observed behaviour, particularly of quantum particles. So yes, given that some logic is predicated on actual events, it would be surprising if it didn't conform to those events.