ajb Posted July 9, 2016 Posted July 9, 2016 Indeed. And the problem reaches even further than initially meets the eye, because if you eliminate local Lorentz invariance, you inadvertently also eliminate the CPT invariance of quantum field theory. That means that, not only would you bring down relativity in the classical realm, but you would also bring down the entire Standard Model with it. However, this does not mean that we cannot formulate QFT on curved backgrounds. We can do this more-or-less as standard for globally hyperbolic space-times. The problem is that we cannot use all our intuition from QFT on Minkwoski space-time. For example, there is no way to single out a vacuum state. For space-times that are not globally hyperbolic we need more algabraic methods - such as local quantum field theory. The problem here is realistic models have yet to be formulated in this way, even on flat space.
Mike Smith Cosmos Posted July 9, 2016 Posted July 9, 2016 'Why' is about cause which is ultimately axiomatic i.e. it is based on a starting presumption. 'How' is about behaviour i.e. it is what is observed, which is what science deals with... So who does the "WHY " bit ? Mike
ajb Posted July 9, 2016 Posted July 9, 2016 So who does the "WHY " bit ? Philosophers try and religous leaders proclaim. 1
Mike Smith Cosmos Posted July 9, 2016 Posted July 9, 2016 (edited) . Yes , but that is non-sensible . And crazy . The WHY bit , was what a lot of the founding FATHERS and MOTHERS , of human knowledge and science for that matter , accomplished up through the early centuries since the DARK AGES until now . If we don't ask a lot of WHY's now , we will bankrupt our Scientific future ! Surely ? And we will go into a FUTURE DARK AGES . -2- (the movie ) Where a lot of computers will be buzzing away doing copious calculations . While society stagnates . Mike Edited July 9, 2016 by Mike Smith Cosmos
geordief Posted July 9, 2016 Posted July 9, 2016 (edited) Does the use of the word "why" anthropicise" events in nature? Does the basic meaning of "why" down the years apply to human intentions(I am speculating linguistically) and not to how events in nature are connected? One event is a precursor to another but there is no mentation involved (and mentation is a complex process whereas events are connected in a direct automatic way without intermediary. Can that be the (another) reason that it is not a valid word to use for objective understanding ? Of course "why" is used loosely to mean but "how" but that covers over its specific implication of a human agency. I know this why/how subject comes up a lot and I have seen the Feynman take on it. Edited July 9, 2016 by geordief
Mordred Posted July 9, 2016 Posted July 9, 2016 (edited) You don't necessarily need to know why. If you can make predictions as to how something influences other dynamics.. For example we know how the cosmological constant influences expansion. We know its extremely constant. We don't know why its constant. That doesn't prevent us from understanding its influence. example two We know the universe exists. We don't know why it exists. example 3. We know the speed of interactions =c. We know nothing goes faster c. We don't know why. Edited July 9, 2016 by Mordred
Mike Smith Cosmos Posted July 9, 2016 Posted July 9, 2016 (edited) . I think a lot of this " science does the how " and not the ," Why ", stems from the " shut up , and calculate " idea that came out of the Copenhagen agreement , ( 1920's/ 1930's I think ) , when there was so much new science to cope with , leading to ( radio activity, relativity, quantum physics , astronomy, rocketry ) to name a few . An explosion of science , there was more than enough to calculate about . But , I am suggesting , ( prepare to be shot down , keep you head down Mike ) , now we need to look to our future and perhaps ask more WHY type questions . To make sure we do not become blinkered.? Mike Edited July 9, 2016 by Mike Smith Cosmos
ajb Posted July 9, 2016 Posted July 9, 2016 and perhaps ask more WHY type questions . But what sort of answers would you be looking for? God made it that way?
Mike Smith Cosmos Posted July 9, 2016 Posted July 9, 2016 example two We know the universe exists. We don't know why it exists. y. . Yes we do ? I spent a week working it out the other day , in another thread ! LOL, Mike
ajb Posted July 9, 2016 Posted July 9, 2016 See how you are falling into metaphysical questions quickly, and not asking true science questions.
Mike Smith Cosmos Posted July 9, 2016 Posted July 9, 2016 (edited) But what sort of answers would you be looking for? God made it that way?.Yes but that , is off the cuff , dismissing. There is probably more difficulty in ( working out ), if that is not a mathmatical hijack , WHY something works , than the HOW. Most women drive cars very well and thoughtfully , but most of them do not know the engineering mechanism , and often put oil in the radiator . Men on the other hand usually know HOW everything roughly works, but are often more inconsiderate , and down right dangerous on the road . Just a minute did I hear " sniper fire " . Mike keep your head down again ! Not again ! Mike Edited July 9, 2016 by Mike Smith Cosmos
disarray Posted July 9, 2016 Posted July 9, 2016 (edited) I think that for the most part, people who read about scientific discoveries or inventions and ask "why" are not usually looking for any ultimate philosophical (religious or poetic) answers, e.g., Why is there something rather than nothing at all? Why does light exist? Why is the cosmological constant what it is and not something else? but rather they are interested in looking for cause and effect relationships (as is perhaps, human nature, to do so), e.g. What causes the universe to expand? What causes the sky look blue? What cause airplanes to stay in the air rather than fall to the ground? Indeed, I would suggest that most basic books for kids and adults that are filled with questions and answers about scientific facts generally follow the format of looking for causes. So when a layperson asks questions about Relativity and Gravity, they are, like classical scientists, looking for cause and effect relationships. What property of matter causes geodesics to curve near them? Would the collision of two photons cause them to slow down as a result? What factors determine the strength of gravitational force? Perhaps it would help the general public if scientists were more clear that they either don't know of a specific cause (e.g., the causal connection between energy/momentum and gravity), or that they don't think that there is a classical cause-effect relationship (e..g, as sometimes is claimed in quantum mechanics), or if there are a variety of causes (as there are in global warming), or if the causes are not what they seem (e.g., the fact that coffee drinkers have higher rates of cancer is not caused by the coffee, which may actually be preventive, but by the fact that coffee drinkers on average smoke more than non coffee drinkers. Edited July 9, 2016 by disarray
ajb Posted July 9, 2016 Posted July 9, 2016 The question is are you looking for a mathematical description of the some mechanisms - so some calculations of some observables that we can measure - or do you want more? If you want more, then you are really getting into metaphysics and maybe religion - both of which cannot give you clear answers.
Mike Smith Cosmos Posted July 9, 2016 Posted July 9, 2016 (edited) WOE , A moderator might well say " what has this got to do with "gravity waves and the aether " . But in a way it has everything to do with ( Gravity Waves and the Aether ) . Because , both space-time , gravity waves, and Aether, . Every one of those three are in the WHY area of unknown , rather than the HOW area of the Unknown . Basically because this area of endeavour is so UNKNOWN . So my case rests for , certainly in this instance , we need a lot more WHY , areas explored. Do we not ? Mike Edited July 9, 2016 by Mike Smith Cosmos
ajb Posted July 9, 2016 Posted July 9, 2016 So my case rests for , certainly in this instance , we need a lot more WHY , areas explored. Do we not ? You should read up on metaphysics and the philosophical implications of modern physics. I hope someone here can offer you some suggested reading as I cannot.
disarray Posted July 9, 2016 Posted July 9, 2016 (edited) The question is are you looking for a mathematical description of the some mechanisms - so some calculations of some observables that we can measure - or do you want more? If you want more, then you are really getting into metaphysics and maybe religion - both of which cannot give you clear answers. Well, perhaps giving accurate answers to questions from the general public about Relativity and Quantum theory seems impossible because of the higher math knowledge needed. But as I look through hundreds of answers about general science questions, including those about gravity and relativity, I in fact see that one can make an attempt to give some sort of answer to just about any question without resorting to higher mathematics: Q: What keeps an airplane in the air: A: Four forces keep an airplane in the sky. They are lift, weight, thrust and drag. Lift pushes the airplane up. The way air moves around the wings gives the airplane lift. Q: What property of matter causes geodesics to curve near them: A: Matter produces gravity. We don't exactly know how this works because we do not have a sufficiently detailed theory of gravity that covers the graininess of matter and energy in a 'quantum theory of gravity'. Anyway, gravity according to general relativity is equivalent to the geometric properties of space-time; in fact they are equal and inseparable descriptions which you are free to move between. Geodesics are geometric objects which represent the straightest possible line that can be drawn between two points, so whenever you talk about what geodesics look like, you are invoking the geometric description of gravity and not its familiar Newtonian description in terms of forces. Geodesics curve near matter because the geometry of space-time is curved...another way to say that gravity is present. Your question is now equivalent to asking why it is that on a flat piece of paper, a straight line is 'straight'. It is the result of the fact that the background space is the way it is. https://einstein.stanford.edu/content/relativity/qanda.html I do not know whether scientists themselves could or should focus a little more on looking for cause-effect questions (for the sake of our future, or whatever). I do not know whether an increased focus on causation would lead to greater scientific progress, particularly when a slavish focus on cause-effect may hinder progress in the field of quantum theory. However, it does seem that looking a little more for explanations, as well as for what measurements reflect what happens, and how we can make predictions, and how we can make rockets, etc., might be productive. Edited July 9, 2016 by disarray
ajb Posted July 9, 2016 Posted July 9, 2016 Well, perhaps giving accurate answers to questions from the general public about Relativity and Quantum theory seems impossible because of the higher math knowledge needed. This is true. For more 'mechanical' situations people can 'see' what is happening - even if they cannot understand the mathematics that is actually involved. But as I look through hundreds of answers about general science questions, including those about gravity and relativity, I in fact see that one can make an attempt to give some sort of answer to just about any question without resorting to higher mathematics: Q: What keeps an airplane in the air: A: Four forces keep an airplane in the sky. They are lift, weight, thrust and drag. Lift pushes the airplane up. The way air moves around the wings gives the airplane lift. So you have a description of the mechanisms involved - all of which can be described using mathematics. Q: What property of matter causes geodesics to curve near them: Well, we know how matter acts as a source of gravity within general relativity. This is the best answer one can give right now. I do not know whether scientists themselves could or should focus a little more on looking for cause-effect questions (for the sake of our future, or whatever). I don't quite follow your point - lots of science is about understanding mechanisms of cause and effect. In physics this us usually understood mathematically.
disarray Posted July 9, 2016 Posted July 9, 2016 (edited) You should read up on metaphysics and the philosophical implications of modern physics. I hope someone here can offer you some suggested reading as I cannot. One can indeed find information about different theoretical and philosophical perspectives about such things as relativity. Philosophy of science example: Harvey Brown takes sides in a debate about the explanatory role spacetime plays. (Although Brown repeatedly expresses solidarity with those who deny that spacetime exists, all parties to this debate are substantivalists -- they accept that spacetime exists. So Brown, too, accepts this view, for purposes of his argument). According to (what Brown alleges is) the dominant view among substantivalists, the geometrical structure of Minkowski spacetime plays some role in explaining why moving rods shrink and why moving clocks run slow. Brown rejects this view. He asserts, instead, that in order to explain why moving rods shrink we must appeal to the dynamical laws governing the forces that hold the parts of the rod together. The geometry of Minkowski spacetime plays no role in this explanation. http://ndpr.nd.edu/news/25025-physical-relativity-space-time-structure-from-a-dynamical-perspective/ Also, one can find information about the philosophical (social) implications of Relativity: Einstein’s theories of relativity have not only affected our daily lives in such basic ways as how we heat our homes, reach our destinations, and measure our days. His theories of relativity were used by philosophers, politicians, and activists to turn moral philosophy upside-down. Relativity fueled postmodernism and philosophic relativism. https://helix.northwestern.edu/article/einsteins-theory-relativity-implications-beyond-science And of course, one can find information as to how Relativity affected philosophy in general: General relativity raises questions about the relation between physics and geometry, denying the latter its traditional role as an a priori discipline. That is the main philosophical relevance of relativity theory. But the theory also bears on the traditionally metaphysical dispute whether all motion is relative and whether space and time are relations among things or exist independently. Both sides of the metaphysical debate cite relativity as supporting their position. http://forums.philosophyforums.com/threads/philosophical-implications-of-einsteins-theory-of-relativity-12199.html In general, I think that the distinction between "how" and "why" is often a gray one, just as, often, is the distinction between science and philosophy. Indeed, both fields tend to have their roots in magic, myth, and religion. Edited July 9, 2016 by disarray
Mordred Posted July 9, 2016 Posted July 9, 2016 As far a what is meant by the terminology and geometry behind spacetime. The best answer is learn the calculations
disarray Posted July 9, 2016 Posted July 9, 2016 (edited) Disarray: I do not know whether scientists themselves could or should focus a little more on looking for cause-effect questions (for the sake of our future, or whatever). I don't quite follow your point - lots of science is about understanding mechanisms of cause and effect. In physics this us usually understood mathematically. I was rephrasing Mike Smith Cosmos' comment: "we need a lot more WHY , areas explored. Do we not ?" My line of argument was that "why" questions do indeed become rather pointless philosophical vagaries unless one can phrase the "why question" in a way that more specifically resembles scientific investigation , e.g., "what causes" type of questions. I take your point that science does indeed do plenty of investigation of causes, as long as the answers seem to be useful....And indeed, evolutionary psychologists point out that the brain is so effective because it is so goal oriented, as opposed to just being idly speculative. One wonders, though, whether a bit more idle speculation would ultimately bring productive results. Indeed, I wonder how many inventions and discoveries began, for the most part, with idle speculation, e.g., Einstein's "I wonder whether one could see ones reflection in a mirror held in front of ones face if one was traveling at or near the speed of light." On the face of it, what possible use could such a question seem to have. As far a what is meant by the terminology and geometry behind spacetime. The best answer is learn the calculations Well, yes, of course. But it does help to learn the concepts as one learns the calculations, and for most people, that often involves asking questions such as "what causes....", "why does that happen," "what if," etc. As I mentioned previously, people have different types and configurations of learning "intelligences," which means that many people, especially when it comes to the mystifying concepts of relativity and quantum theory, will nowadays want all sorts of educational aids (e.g., metaphors, illustrations, stories, film clips, descriptions, explanations, etc.) in addition to just learning the math. In many people's minds, just learning the math is just rote learning (despite the fact that those proficient in math can see logical connections that the average person can't). And rote learning, as we know, may be effective, but is often discouraging and unsatisfying. Edited July 9, 2016 by disarray
Mike Smith Cosmos Posted July 9, 2016 Posted July 9, 2016 (edited) .------------------------------- WHY is there not an ' Aether like Medium ' within space-time , for gravity waves to propagate? When nearly every other wave , vibration , and oscillation , in the entire Universe , uses such a type of facility to efficiently propagate its energy or information ? -------------------------------- . Mike Edited July 9, 2016 by Mike Smith Cosmos
ajb Posted July 9, 2016 Posted July 9, 2016 .------------------------------- WHY is there not an ' Aether like Medium ' within space-time , for gravity waves to propagate? When every other wave , vibration , and oscillation , in the entire Universe , uses such a type of facility to efficiently propagate its energy or information ? -------------------------------- Not a physics question - we have no idea why and cannot hope to answer that.
Mike Smith Cosmos Posted July 9, 2016 Posted July 9, 2016 (edited) Not a physics question - we have no idea why and cannot hope to answer that.Well ! , for something so , overarching , important , necessary and interesting , we jolly well should try and find out , if we are scientists, this is our subject ( nobody else's ) ? Who else is there that could approach such a ' Question ' ? If we were in the same boat with another discipline , like medical , and we had an outbreak of Bubonic Plague . A practitioner would not just say " Not my Remit " . It is ALL relevant ' hands to the mill ' is it not . Not " Bubonic Plague" no , don't know why we should have one in 21 st Centuary , Not a relevant question. We would have to all have a go at using whatever mental dexterity we have available to help with answering ( WHY, have we got a Bubonic Plague in the 21 st Century ? ) Mike Edited July 9, 2016 by Mike Smith Cosmos
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