Link: On the Origin of Gravity and the Laws of Newton.
Verlinde won the Spinoza prize (2.5 million euro) last year for his theory. He also thinks it explains dark energy.
http://www.science20.com/hammock_physicist/it_bit_how_get_rid_dark_energy
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Before the big bang
- Thread starter Mazulu
- Start date
Link: On the Origin of Gravity and the Laws of Newton.
Verlinde won the Spinoza prize (2.5 million euro) last year for his theory. He also thinks it explains dark energy.
http://www.science20.com/hammock_physicist/it_bit_how_get_rid_dark_energy
From the same article,Link: On the Origin of Gravity and the Laws of Newton.
Verlinde won the Spinoza prize (2.5 million euro) last year for his theory. He also thinks it explains dark energy. http://www.science20.com/hammock_physicist/it_bit_how_get_rid_dark_energy
On the Origin of Gravity and the Laws of Newton said:The statistical tendency to return to a maximal entropy state translates into a macroscopic force, in this case the elastic force.
So if we wanted to generate an artifiical gravity field, then we have to do something that maximizes entropy. We want to try to duplicate the phenomena of gravity using the same mechanisms that work for natural gravity. Is this a fair statement?
From the same article,
So if we wanted to generate an artifiical gravity field, then we have to do something that maximizes entropy. We want to try to duplicate the phenomena of gravity using the same mechanisms that work for natural gravity. Is this a fair statement?
I think that Verlinde's theory is just one of several entropic gravity theories. His involves the holographic theory which many find dubious. The set of people that find entropic gravity dubious is probably larger. But as we all know we don't vote on scientific truth.
The key phrase in all these entropic theories is "degrees of freedom". If I understand it, the curvature of space provides a statistical bias for movement or position in the direction of center of mass and center of curvature. If you consider a sphere centered on the center of gravity, we know that the space inside the sphere is a little larger than the surface area of the sphere would lead us Euclideans to believe. So for a particle sitting on the sphere, there are more degrees of freedom toward the mass and less away. Any random motion of the particle would be biased toward the center. Perhaps the wave function of the particle is involved. Particle spin is probably also involved. It is probably way more complex than that but that is my general impression (which could be completely wrong).
So I don't think you will find any gravity beam technology in these entropic theories unless you can think of a way to bias degrees of freedom in a controlled direction. We would have to assume that bending space is out of the question, since that would mean controlling large amounts of matter and energy. I gather that you are operating within the constraint that photons are the answer. Photons do carry energy and so they do contribute to the curvature of space to a small degree. But it seems to me that any mechanism to use that for producing gravity (esp using photons) would wind up being a Acme product in a Roadrunner cartoon. I think I know how I would approach finding a solution to such a problem but it would possibly show that such a thing is impossible. You seem to approach problems by assuming a solution is always possible. My experience tells me otherwise.
Well, if I have to bias degrees of freedom in order to come up with a gravity field, then information theory comes to mind. But I have to find my text books and review this stuff.So I don't think you will find any gravity beam technology in these entropic theories unless you can think of a way to bias degrees of freedom in a controlled direction. We would have to assume that bending space is out of the question, since that would mean controlling large amounts of matter and energy. I gather that you are operating within the constraint that photons are the answer. Photons do carry energy and so they do contribute to the curvature of space to a small degree. But it seems to me that any mechanism to use that for producing gravity would wind up being a Acme product in a Roadrunner cartoon. I think I know how I would approach finding a solution to such a problem but it would possibly show that such a thing is impossible. You seem to approach problems by assuming a solution is always possible. My experience tells me otherwise.
But vaguely, I remember that the bit rate is less than/equal to twice the sampling frequency, or something like that.http://en.wikipedia.org/wiki/Nyquist_rate said:The Nyquist rate is the minimum sampling rate required to avoid aliasing, equal to twice the highest frequency contained within the signal.
The idea is to try to use the bit rate to satisfy the need for "degrees of freedom". If we vary the sampling frequency (linearly), then we vary the bitrate and hopefully degrees of freedom. Like I said, it's been a long time since I've looked at this stuff.
Well, if I have to bias degrees of freedom in order to come up with a gravity field, then information theory comes to mind. But I have to find my text books and review this stuff.
But vaguely, I remember that the bit rate is less than/equal to twice the sampling frequency, or something like that.
The idea is to try to use the bit rate to satisfy the need for "degrees of freedom". If we vary the sampling frequency (linearly), then we vary the bitrate and hopefully degrees of freedom. Like I said, it's been a long time since I've looked at this stuff.
So what are you going to do? Hook up some video encoders on the front of your space ship? I have read that the holographic principle does say that information is involved with gravity and spacetime, but the amount of information required for any perceivable effect is many many orders of magnitude more than you can muster with some electronic circuits. Think about it. All the information in the entire earth is required to make 1G of gravity. The amount of information in a spaceship has to be much much lower.
That's the best idea I can come up with. But you have the right idea. Frequency sweeps also mean that you're emitting a field with a changing bit rate, one might hope to get the degrees of freedom to change as a function of time in some linear way. Trying to curve space-time in some way that leads to propulsion is like poking a mountain with a feather.So what are you going to do? Hook up some video encoders on the front of your space ship? I have read that the holographic principle does say that information is involved with gravity and spacetime, but the amount of information required for any perceivable effect is many many orders of magnitude more than you can muster with some electronic circuits. Think about it. All the information in the entire earth is required to make 1G of gravity. The amount of information in a spaceship has to be much much lower.
I can't work out the math, I can only suggest the idea that while we can't use Juper mass amounts of mass-energy to power an Alcubierre drive, maybe we can pull some entropy trick on nature. Maybe we can emit some EM field with a changing entropy. If done right, maybe we can get the same Alcubierre drive result using entropy instead of energy.
What good is all of this holographic universe chatter if we can't try to take advantage of it with some kind of engineering that mimics gravity?
You can't appreciate how much time and thought it took to come up with that little trick of causation. Gravity causes light to redshift; why can't it work in reverse? In chemistry, chemical reactions can run forwards or backwards.
I have been thinking about this question or reversibility. Nobody here ever really addressed this. While I am not too excited about your gravity beam idea, I think this reversibility question is very interesting. I am pretty sure that it can't work in reverse but so far I have not been able to explain why. Currently I am taking a course in Abstract Algebra and I think the answer lies there. A smart guy friend of mine suggested that algebra holds answers to a lot of very interesting question. All these processes, such as the one that allows warped spacetime to change the wavelength of a photon, are transformations. If you could write down the transformation in matrix or more probably tensor form, then all you need to do is see whether that tensor is invertible. In other words if some transformation takes the spacetime curvature to photon wavelength then its inverse would take the wavelength and transform that back to the curved space. I can't do this yet and probably will not get to working with tensors for many months, but my guess is that there is no inverse. My thinking is that a photon is a simpler object than space time curvature, and that would seem to mean that it is a one way transform. But I am not very far into the class and am taking it slow so don't expect me to have an answer anytime soon.
I have been thinking about this question or reversibility. ... All these processes, such as the one that allows warped spacetime to change the wavelength of a photon, are transformations. If you could write down the transformation in matrix or more probably tensor form, then all you need to do is see whether that tensor is invertible. In other words if some transformation takes the spacetime curvature to photon wavelength then its inverse would take the wavelength and transform that back to the curved space.
I should add that if the transform is reversible, that still does not mean your gravity beam idea will work. The problem is that your photons never actually change wavelength. So you also need to see if your chirp idea has any similarity to the actual transform. I think that you will find that there is nothing going on that looks like a transform from curvature to wavelength. I am pretty sure that it is possible to create mathematical models of both the actual transform and your simulated transform. So even if the curvature to wavelength transformation is reversible, you also need to make a curvature to simulation transform, and see if that is reversible. If it is then you only need to "implement" (as you like to say) that transformation. And it also should predict the actual experimental results.
You could use this method to find new ideas for gravity generation. Just get a program like MatLab or similar. Or just write simulations using tensors in whatever programming language you wish.
Disclaimer: I am really talking way above my skill level here so you might want to talk to someone knowledgable about this.
I don't think he was saying that the bored photons where responsible for what was happening, only that they don't get bored because they don't experience time. He was trying to find evidence in the CMB of gravitational waves, but surprise, surprise they didn't find any evidance of gravitational waves from black holes coming together from before the big bang. I think it would mostly be because gravitational waves don't actually exist, so then you wouldn't find any evidence of them in the CMB anyways.I watched the video. I didn't understand how bored photons waiting around for googles of years in the last aeon became the big bang of this aeon. It left me with the feeling that whatever happened to lead up to the big bang is not well explained by science.
I don't think entropy and gravity have any fundemental quality with each other. The amount of entropy is just different near a source of gravity. Things should always move out to be disorderly. But gravity pulls everything together, so then they don't have much more to do with each other than just that. Forces of nature affect the entropy but entropy itself is not a force. I think it would only take a better understanding of dark energy or the inflaton field or why the universe expands the way it does in the first place. If space is actually increasing in distance and this what causes the red shift of light traveling accross the universe, then it would allow for FTL travel. Galaxies travel FTL away from us because of this. So then creating a warp bubble probably wouldn't even be necessary, you would only have to increase the amount space was expanding at the location of a ship.So if we wanted to generate an artifiical gravity field, then we have to do something that maximizes entropy. We want to try to duplicate the phenomena of gravity using the same mechanisms that work for natural gravity. Is this a fair statement?
Chemistry has reversible chemical reactions. http://en.wikipedia.org/wiki/Reversible_reactionI should add that if the transform is reversible, that still does not mean your gravity beam idea will work. The problem is that your photons never actually change wavelength. So you also need to see if your chirp idea has any similarity to the actual transform. I think that you will find that there is nothing going on that looks like a transform from curvature to wavelength. I am pretty sure that it is possible to create mathematical models of both the actual transform and your simulated transform. So even if the curvature to wavelength transformation is reversible, you also need to make a curvature to simulation transform, and see if that is reversible. If it is then you only need to "implement" (as you like to say) that transformation. And it also should predict the actual experimental results.
You could use this method to find new ideas for gravity generation. Just get a program like MatLab or similar. Or just write simulations using tensors in whatever programming language you wish.
Disclaimer: I am really talking way above my skill level here so you might want to talk to someone knowledgable about this.
It depends upon the change in Gibbs free energy.
http://en.wikipedia.org/wiki/Gibbs_free_energy
Gibbs Free energy includes potential energy AND a change in entropy.
I don't think entropy and gravity have any fundemental quality with each other. The amount of entropy is just different near a source of gravity. Things should always move out to be disorderly. But gravity pulls everything together, so then they don't have much more to do with each other than just that.
Your intuitive approach to science is never going to serve you very well. We all do it, some more than others. I am more towards your and Mazulu's end of the spectrum than I would like to be. I hope to someday correct that at least partially. But it is a really bad idea to intuit physics simply because it is very often wrong.
The second law doesn't say that things converge towards a spatially uniform configuration. The second law says that the physical systems evolve towards states of a greater entropy (a measure of disorder). It's a completely different thing than uniformity. What Robert presents as "our intuitive understanding of the second law" is actually completely orthogonal to the second law. It has nothing to do with it in general. ...
Yes, gravity tends to clump things. They evolve into "compact" configurations. But this fact is in no tension with the second law of thermodynamics whatsoever. The only reason why Robert thinks that there is a tension is that his thinking is sloppy - perhaps deliberately sloppy. The existence of the attractive gravitational force is not only consistent with the increasing entropy: one makes another more natural in this context. In fact, the maximally clumped configurations of matter tend to maximize the entropy - they're the black holes that carry the maximum entropy that can be squeezed into the same volume.
Whenever attractive gravity dominates, higher entropy becomes associated with non-uniform matter distributions, and these two descriptions therefore apply to a typical state of matter in the future. The previous sentence may sound counter-intuitive to someone but if it is so, it proves that his or her intuition is failing completely (because every sensible person knows that gravity naturally clumps things and future configurations naturally have a higher entropy so clumped objects that will actually be created or evolved in the future must have a higher entropy). The emotions show nothing wrong about cosmology, thermodynamics, or their union. Science is not about the emotions or intuition of uneducated, slow people with bad scientific intuition.
Although it may sound unpopular, there are many fewer people than 6 billion in the world who can actually use their intuition to answer both deep and elementary physics questions, and Robert is unfortunately not in the lucky group. Well, I know that people prefer to hear that everyone should build on their intuition because everyone, including mediocre crackpots of Garrett Lisi's caliber, are new Einsteins. Well, people like to hear it but it is a lie. There are only 100-200 intuitive Einstein equivalents in the world and none of them thinks that Lee Smolin or Garrett Lisi is a good physicist. Everyone else - about 6.5 billion people - should mechanically learn the important insights found by the smarter people.
From: http://motls.blogspot.com/2009/01/myths-about-thermodynamics-and-gravity.html
Chemistry has reversible chemical reactions. http://en.wikipedia.org/wiki/Reversible_reaction
It depends upon the change in Gibbs free energy.
http://en.wikipedia.org/wiki/Gibbs_free_energy
Gibbs Free energy includes potential energy AND a change in entropy.
I don't see how that contradicts anything I said.
It has so far, but I guess that would depend on what you think of as disorder and order. I always tend to get the two mixed up. Say you failed to clean up your room so then you had various things slung all over distributed fairly evenly throughout it. Would you say that is more orderly? I keep forgetting that cleaning up your room increases its disorder...Your intuitive approach to science is never going to serve you very well. We all do it, some more than others. I am more towards your and Mazulu's end of the spectrum than I would like to be. I hope to someday correct that at least partially. But it is a really bad idea to intuit physics simply because it is very often wrong.
From: http://motls.blogspot.com/2009/01/myths-about-thermodynamics-and-gravity.html
All entropy really means is that there are no outside forces acting on things that make them behave one way or another. That is why it is one of sciences biggest riddles. There is no force that acts on things that make things run one way forward in time and another if backwards in time. If entropy actually had an effect on things as they moved forward in time then we would have already solved this riddle. They are just cut loose and allowed to travel one way or another. The enrtropy is just a generalization of the combined random behaivor.
I don't think the person who assigned order and disorder to entropy was even that scientifically intuitive.
It has so far, but I guess that would depend on what you think of as disorder and order. I always tend to get the two mixed up. Say you failed to clean up your room so then you had various things slung all over distributed fairly evenly throughout it. Would you say that is more orderly? I keep forgetting that cleaning up your room increases its disorder...
I would say to that the act of cleaning up your room is going to burn some calories. That is heat. That is entropy increasing. It is also true that if you messed up your room it would burn some calories. That is entropy increasing. Entropy always increases.
That may be true for the air in your room, but not for any of the objects in it. But then your AC would kick on to keep it the same room temperature after you where done...I would say to that the act of cleaning up your room is going to burn some calories. That is heat. That is entropy increasing. It is also true that if you messed up your room it would burn some calories. That is entropy increasing. Entropy always increases.
That may be true for the air in your room, but not for any of the objects in it. But then your AC would kick on to keep it the same room temperature after you where done...
Actually the act of moving the objects around will heat them up. Friction with the environment. Heck, even the photons reflecting off of shiny objects will cause bursts of infinite energy all over the room, that would heat things up considerably. Intuitively speaking that is.
You're trying to view entropy from the wrong angle. An increase in entropy simply means there is less available energy. Like a wound-up clock running down; or a decrease in temperature difference inside a system.
"Order" and "disorder" are slightly misleading terms and are best avoided. Which is more ordered: 2 atoms of hydrogen and one of oxygen - or a single molecule of water? Looking at both in terms of order and disorder can be confusing. The correct answer is the molecule of water has more entropy because in the other case - before the atoms combined - there was energy available.
"Order" and "disorder" are slightly misleading terms and are best avoided. Which is more ordered: 2 atoms of hydrogen and one of oxygen - or a single molecule of water? Looking at both in terms of order and disorder can be confusing. The correct answer is the molecule of water has more entropy because in the other case - before the atoms combined - there was energy available.
LOL, your just mad because in the one experiment similar to what I was saying that could be shown in a video, did show an increase in energy even though it was just through a cable and not even an actual waveguide.Actually the act of moving the objects around will heat them up. Friction with the environment. Heck, even the photons reflecting off of shiny objects will cause bursts of infinite energy all over the room, that would heat things up considerably. Intuitively speaking that is.
I would say that Human beings can counter the effects of entropy. They just didn't have human beings inside of the box of gas when they performed the experiment. Just like they didn't have electromagnetic energy inside of the box when they performed the experiment.
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You just have to switch the words "order" and "disorder" around. So then a single molecule of water from 3 atoms would be more disordered. They would no longer be "put up" in their seperate places.You're trying to view entropy from the wrong angle. An increase in entropy simply means there is less available energy. Like a wound-up clock running down; or a decrease in temperature difference inside a system.
"Order" and "disorder" are slightly misleading terms and are best avoided. Which is more ordered: 2 atoms of hydrogen and one of oxygen - or a single molecule of water? Looking at both in terms of order and disorder can be confusing. The correct answer is the molecule of water has more entropy because in the other case - before the atoms combined - there was energy available.