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The End Of Gravity As a Fundamental Force
An anonymous reader writes "At a symposium at the Dutch Spinoza-instituut on 8 December, 2009, string theorist Erik Verlinde introduced a theory that derives Newton's classical mechanics. In his theory, gravity exists because of a difference in concentration of information in the empty space between two masses and its surroundings. He does not consider gravity as fundamental, but as an emergent phenomenon that arises from a deeper microscopic reality. A relativistic extension of his argument leads directly to Einstein's equations." Here are two blog entries discussing Verlinde's proposal in somewhat more accessible terms.
Update: 01/12 04:48 GMT by KD : Dr. Verlinde has put up a blog post explaining in simpler terms the logic of the gravity from entropy paper. He introduces it with: "Because the logic of the paper is being misrepresented in some reports, I add here some clarifications."
Update: 01/12 04:48 GMT by KD : Dr. Verlinde has put up a blog post explaining in simpler terms the logic of the gravity from entropy paper. He introduces it with: "Because the logic of the paper is being misrepresented in some reports, I add here some clarifications."
But it sure sounds promising.
And even if it's not true, if the math works, it still might be useful. Newton's and Einstein's theories aren't strictly "true" but they are incredibly useful despite that.
Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
That's one funny thing about math, "close doesn't count", until you get to a certain advanced point. Then we say "this works for all but a few special cases... close enough."
I work for the Department of Redundancy Department.
I couldn't begin to assess how plausible this theory is; neither could most of the people on Slashdot. However, I do know the arXiv is not a peer-reviewed journal, which mean that we can't even rely on the peer-review system to gain information on how sound the underlying research is. Many excellent publications appear on arXiv before being published in excellent journals, but some fairly questionable research ends up there as well.
Rather than post completely uninformed comments on the subject, leave that to people in the field.
So if this is the future...where's my jet pack?
You assume the destination is more important than the journey, young Grasshopper.
Table-ized A.I.
If the math works, then "shut up and calculate" (ascribed to both Dirac and Feynman regarding quantum mechanics). Non-mathematical forms of understanding may follow, eventually, perhaps even including opinions on "truth". If the math does not work, the hypothesis will be quickly abandoned or revised.
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
Philosophers and religious folk will argue over what that might mean.
And while they are all deciding whether God/god/Xenu programmed the universe via voice command or a PADD, I'll be working to convince the Creator that I am self-aware, thus securing a free warp-capable shuttlecraft!
On a more serious note, as is always the case, this "new" line of thought seems to be a better description of something we observe, yet still constrained by our ability to model and describe things. As IANATP (I am not a theoretical physicist, more the applied kind), what does this potentially bring us, other than that better description? You know us engineers will be snickering until you show us something we can do or make shiny with this.
A theory is as good as its predictive power. If it predicts reality better than the previous one, who cares if it's "true", whatever that may mean.
May the source be with you.
The one funny thing about the way the majority of people use math, "close does count", until you get to a certain advanced point. Then we say "this works for all but a few special cases... close enough"
Obviously Newtonian gravity is much more understandable to your average person than say general relativity and also offers a good aproximation of expected behaviors of the physical world.
On the Oregon Cost born and raised, On the beach is where I spent most of my days
My understanding of an "entropic force" is that it can be described in terms of fundamental forces. The pressure in an ideal gas, for instance, can be derived by looking at the impulse created by a single molecule, and then extending that to a collection of N molecules. This guy seems to be saying that gravity is an entropic force and therefore NOT a fundamental force, but it seems to me that entropic forces are just an abstraction that allows us to ignore the underlying fundamental forces. Of course, I didn't read the whole article, but what I read was poorly written and that doesn't inspire a lot of confidence. Maybe I'll take another look if it gets published.
The upshot then is not that you get the right value for G at the end but that you get Newton's inverse square law (up to a scalar) which by itself would be really impressive even if one can't a priori get the value of G.
The inverse square relation comes easily from the fact of 3 spatial dimensions. The gravitational flux from a mass is spread out over a surface of a sphere, whose area is proportional to the square of the radius. It is a perfect analogy of electric fields.
It is possible to derive the same form in many different ways. It is a nice exercise to play with alternative theories of gravity, and see how they are similar or different. However, general relativity has a crucial deviation from the inverse square law, which results in the anomalous orbit of Mercury, for example. This does not mean GR is the final correct answer, of course.
Escher was the first MC and Giger invented the HR department.
Well, it does make a jump from a fundamental force we can't seem to detect into a latent, emergent phenomenon which we, er, also can't detect the source of.
*EVERYTHING* in the universe is based on some fundamental thing which we "cannot detect the source of". Even something as simple as math, or logic, is based on a set of axioms, or givens, which can never, themselves, be explained in terms of where they come from.
In physics, things like quarks (or if there's something that makes those, then that thing), or the fundamental forces, are all currently unexplained regarding why or how they exist.
What this work does (or at least, claims to do) is connect gravity with the rest of physics.
But your opening line is actually quite wrong:
Well, it does make a jump from a fundamental force we can't seem to detect into a latent, emergent phenomenon which we, er, also can't detect the source of.
Not at all. Presently, gravity is an axiom. It is a thing that exists, and upon which much is built, but below which nothing can be known. With this theory, gravity is just like things built upon gravity (such as orbits, gravitational singularities, etc.), which can all be explained by something below them. At some point, everything ends up as an axiom. This theory removes one of science's present axiom, and any time you can do that, you've done nothing less than fundamentally enhanced our understanding of the universe.
If gravity is truly not fundamental and works as described by the paper, then you can kiss the antigravity machine goodbye!
Then we say "this works for all but a few special cases... close enough."
Actually we don't - we just say that we don't know any way to do it better and it seems to work outside of these cases....so until someone can come up with something better we'll go with the best we have.
Do you have any concrete prediction of religion which became true? And no, "everything will happen exactly as the god wants" is no prediction (unless you accompany it with an exact description of what the god wants). It is an explanation, though (it explains why things happen as they do, namely "because god wants them that way"), it's just not a very satisfying explanation (well, unless you are a True Believer(TM), then the explanation is perfectly satisfying :-))
The Tao of math: The numbers you can count are not the real numbers.
You're muddling the distinction between the concept of exact measurement with exact model.
When we say that Newtonian physics is "about" right, we're saying that, given the properties of the area of the physical world we inhabit (about sea level on an Earth sized planet), Newtonian physics is a model that can predict the behavior of bodies in motion pretty accurately. Relativity theory models those same bodies more accurately, and in a wider area of application. In this way, our models of the universe could be said to be asymptotically approaching "correctness".
When we say that the speed of light is "about" 3 x 10^8 m/s, everybody but the most retarded physics students know that it's not exactly that, but that that number is close enough that it's usable. Same as saying pi = 3.141 and g = 9.81 ms^-2 at sea level on Earth. Those are imprecise but "close enough" approximations of natural constants which do not have integer values, so we just truncate them to the desired level of accuracy for the current use. I don't need pi to a hundred places to be able to triangulate the hats on the sports oval for the experiment in 10th grade. Hell, pi to eleven places will calculate Earth's circumference to within a millimeter, which is "accurate enough" for pretty much all everyday uses.
Don't mix these two concepts, a model can be 100% accurate even if we are incapable of measuring fully, and vice versa.
I hate printers.
Insight.
You know, when Newton figured out the fundamentals of physics, he didn't do so to produce new shiny toys, but to understand the universe. Newton was philosopher, not engineer.
The Tao of math: The numbers you can count are not the real numbers.
one key one was newton's assumption that the effect of gravity was instant.
If you mod me down, I will become more powerful than you can imagine....
Instead of seeing ourselves as separate from everything around us, this view allows us to recognize that we are embedded in a fractal feedback dynamic that intrinsically connects all things via the medium of a vacuum structure of infinite potential. This research has far reaching implications in a variety of fields including theoretical and applied physics, cosmology, quantum mechanics, biology, chemistry, sociology, psychology, archaeology, anthropology,
My bullshit detector just asplode.
Yo dawg, I heard you like the Ackermann function, so OH GOD OH GOD OH GOD
Well, that's what I meant. "Earth' circumference" is a reasonable concept that is usable, despite the fact that Earth is not a regular sphere, nor is its surface smooth.
Modelling the Earth as a sphere is a better model than the flat Earth model, but not as good as modeling it as an integrated ellipse. Yet, this is still not a perfect model. (I actually don't know what the current "best" model is. I only know that Earth is slightly flattened due to centrifugal forces and other effects.)
I concede, however, your point that a model can't be proven to be correct if its accuracy has been demonstrated to the limit of our ability to measure it. That's what I was alluding to in mentioning Newtonian physics; the model was good enough to measure their physical universe to the accuracy that they had access to. I.e., relatively rudimentary experiments carried out on the ground.
I think you and I agree, I was just not clear in my earlier post what I meant. Apologies for that.
I hate printers.
just because every science article like this has a high number of posts saying "correlation is not causation" does not mean that science articles cause "correlation is not causation" posts. Correlation is not causation.
> Is our model of PI more accurate than our measurement of a circle in reality?
Good question; I've often wondered myself, and wish to know the answer.
"Gravity however, opposes entropy, since it pulls particles together, into a lower entropy state."
I'm not well versed on entropy / thermo-dynamics. The basis of making any of this intuitive is an elastic band - which apparently is a good description of a thermal entropy-chamber with an external force stretching a polymer chain. The temperature affects the restorative force which resists the stretching. In general, this force is not considered a fundamental force. It is the result of entropy - of individual atoms traveling random paths such that a lowest energy state is sought. The net migration of atoms - the diffusion can, on a macroscopic level, have a directional force measured. But this isn't a direct force (like weak-electro-magnetic or the strong nuclear force) - instead it's a net-force - aggregating all atomic paths given a particular orientation of matter at a given point in time.
The next critical piece of information is the mathematical representation of the universe as a 2D holographic surface. Or rather, looking at any particular event as a 2D surface that encloses any piece of information we wish to observe/describe. All the matter/energy/information within the surface is described mathmatically by the surface itself.. And thus the surface carriers information.. And consequently has an information density - the author describes a number of bits per unit area of information.
The author describes a maximum possible density - a minimum surface area that can hold a bit. And this is described as the event horizon of a black-hole.. Namely a 2D sphere with 100% information storage.. Any information that is absorbed by the black-hole corresponds to a growth of the sphere such that the total area has increased slightly, and thus can facilitate an extra bit of information.
Thus any region of space can be thought of as having an enclosed surface.. And if there is ANY energy there-in, there will be bits of information on that surface of a corresponding density.
For two surfaces enclosing different sizes of matter/energy, the density of the surfaces will be different.. Likewise, if two surfaces enclosing the same matter are of different sizes, the density will be different.
The final piece is describing a natural migration of this energy density. Namely, that energy/information that 'moves' from one surface to another will be traveling through different information-densities. Much like a gasious atom moving through a medium. The assymetries in the information-surfaces (like the assymetries in the atmosphere) will constrain the degrees of freedom of the energy. There net effect is equivalent - diffusion. Or more generally, that the laws of thermodynamics dictate the aggregate forcing functions used to describe the enclosed system.
The author then uses various equations to bring about entropy to the classical Neutonian F=ma (specifically F = Gm/r^2), and more impressively into red-shift equations for Einsteins relativity. Meaning he's able to relate the classical force of gravity into more-intuitive/tangible elasticity equations.
The end result is that he feels he can do away with action-at-a-distance, space-time, and gravity as a force. By saying that the attractive force of stellar bodies is really the diffusion of energy as defined by the laws of entropy. Whenever you have a 'gradient' between two adjacent arbitrary surfaces, you'll have a diffusion (as you'd naturally expect in fluids / gasses). This gradient typically has a complex measureable path between 2 or more massive bodies.. And thus any matter traveling along those paths will experience reduced degrees of freedom consistent with entropy/diffusion. The net motion can be measured as a forcing function equivalent to Neuton/Einstein. But the important thing to take away is that this is a NET motion.. NOT a natural force exerted on each particle - as a charged electric field would produce.
This is fundamentally why we have so much difficulty trying to incorporate gravity i
-Michael
It also seems to tie together arrow of time and gravity. The only accepted explanation for the fact that time is unidirectional is that entropy increases with time.By tying the concept of gravity and time together, this theory probably puts us closer to "Grand unified theory".
http://slashdot.org/submission/1062723/Cheap-mobile-data-plan?art_pos=2
I didn't realize $4.99 + tax was advanced math. We almost always use math in a close enough context. Close doesn't count in pure math, but as soon as you apply it to something real you're always talking about close enough.
When someone simply holds an opinion, maybe even based on some subset of all known facts, that there is no God, that isn't by itself a religion. But the claim that Atheism as a formal, organized opinion isn't a religion is a different position. If you look at these threads on Slashdot, they start off about subjects such as sciences, and sooner or later, fanatics for both sides start arguing about God. While personally, I don't think I'm a fanatic, and you probably don't think you are either, I admit there are religious fanatics galore on my side. On your side, you have a bunch of Atheist religious fanatics, whether you acknowledge them or not. I'm talking about the Atheists who post the "everybody who isn't a moron knows that Atheists are superior." type remarks. Notice that we have some of that 'intelligence is the absence of religion' part right above this thread.
This sort of atheism is a religious belief system, as in: "My Atheism proves I'm smarter, and my being smarter justifies my Atheism." That's the exact same mechanism as "Of course the Bible was written by God, it says so right in the Bible." Your movement has its ignorant and abusive people who rely on circular logic and cliches to justify their opinions rather than any acts of reason. Your fanatics behave just as badly as our fanatics. You even have organized spokespersons who claim to speak for you. You may find some of them distasteful, or think that they are wrong, but if you are a typical rational atheist you tolerate them, just as many Christians tolerate Jerry Falwell or Pat Robertson even while disagreeing with much of what they espouse. What makes your beliefs a religion is you have plenty of religious fanatics, just as we do.
Who is John Cabal?
I believe you are conflating the general usage of the word 'theory' with the scientific usage of the word 'theorem'.
Is our model of PI more accurate than our measurement of a circle in reality?
There are no naturally occurring perfect circles. A circle just the concept of a perfectly symmetrical ellipse. I could be mistaken but I'm almost positive that its impossible to form a perfect circle in a universe were there are more then 2 particles interacting.
Cool art gallery, if you're into that sort of thing.
Well He said that He would take us out of the Land of Egypt and He did that... Oh, you wanted predictions in terms of physics. And for current-day events. Yeah, God's an arbitrary SOB sometimes.
For instance the question of why there is inertia is addressed by the work of Higgs and the theoretical Higgs boson.
No, it isnt addressed by it. This is just another theoretical model.
In the case of gravity, begin with Newton.
F = Gm'm"/d^2
This is a model. This does not explain why there is gravity. The fact that we eventually found instances that contradict it lead to another model, general relativity. General relativity doesnt explain why there is gravity either, and we have since found cases where this model too many not hold ('dark energy'.) The Higgs wont dig us out of this lack of understanding, because nobody understands why things at these scales (see the photon) behave the way they do.
120 years ago things were thought to be much simpler. Proton, Electron, and then Photon. That was it. Back then we could at least understand the models, but understanding the model is not the same as understanding reality (obviously, since we were wrong.) Now we have quantum theory and particles behaving like waves (or maybe its waves behaving like particles) culminating in the situation that nobody really even understands how reality could even be like the models.
The model is all we have, and its not a description of reality, but instead a tool to predict observation.
With a good enough model I can tell you where every pool ball on the table will end up. That model need not represent the reality that the pool balls are made up of trillions of atoms each made up of quarks and electrons, that the balls bounce against each other because the individual electrons repel each other while also binding atoms together, that the amount of kinetic energy (heat) in the balls will change, that even the shape of the balls changes as they move.
The pro-pool player need not understand what is really going on to make the shot. His model, just like the model with individual atoms, is just a tool to make predictions. The little boy can ask "why" and the adult can answer, but that answer is not actually correct.
Why do things in motion tend to stay in motion? Nobody knows! We call it Inertia.
"His name was James Damore."
He's not abusing the word "understand" (well, maybe a little), he's just using it in a slightly different context. You may be able to predict your wife's behaviour, but if it came down to some sort of rule (she will always choose option 2 in the bottom half of an hour, option 1 in the top half for example) you might not say you understood her. You could predict her behaviour, but you would have no idea why she made choices that way. In reality, you do understand, at least to some degree, why she makes the choices she does.
Copernicus, Kepler et. al. correctly deduced that the planets move in ellipses around the sun (that is, how the planets move), but they had nothing to say about why they should do so. It wasn't until Newton came along that we understood some of the why.
It's true that our understanding of the mechanisms behind quite a bit of physics is a little fuzzy. Until fairly recently both inertial mass and gravitational mass just were. We didn't have any real explanation for why they exist, whether they were always equal, etc. The Higgs field explains much of that, and also connects it with some interesting cosmology fairly elegantly.
> This sort of atheism is a religious belief system
You are technically correct in that when I go to dictionary.com, the word "religion" as it's defined there could be used to describe ANYTHING. You are using that as an excuse to attempt to surrepticiously equate our logic with your lack of logic, and claim they're the same, or at least imply that our belief system is just as groundless as yours.
This is what you are saying: "Hey look, we've got a belief system, you've got a belief system, that means you're just like us! How dare you criticize our position, how dare you impune the names of people who have a belief system."
So let's stop using the word religion, as technically you are correct, it clearly does not differentiate the two positions. (( I strongly object to the use of the term Religion to describe my belief system, as it's primary use (despite what dictionaries say) is equated with "belief in imaginary deities", and my belief system clearly does not include that. I strongly object to having my belief system associated with your belief system. That's what calling it "a religion" does. ))
So what shall we call your religion or belief system? I suggest "magic".
What shall we call my religion or belief system? I suggest "science".
There. No way in hell you can claim science is magic and thus suggest we've got anything in common, other than the fact that we both have a "belief system". You believe in magic. I believe in science.