Actually concave would also be a de Sitter space. Concave is just like convex - just looking it from the other side. If you take any point on a convex or concave shape, you'll see it curves in the same way in every direction. But a saddle curves up in one direction and down in the other direction. That's what makes it anti de sitter
> Well, it helps by ensuring that less energy is wasted pursuing it. See?
So... basically you'd call a halt to all theoretical physics since none of the current new theories are currently testable, and won't be without further investigation.
If you can prove that string theory isn't ever going to be testable, then you can win a nobel prize.
If you are arguing that it's not possible to test it at this very moment, then you should support trying to improve on it, so I don't see how calling it not science helps anything.
I don't know if you're just making a weak joke or if you're actually making a brilliant joke because that's exactly what does happen.
Basically you end up with a whole bunch of terms that are infinity (like from trying to divide by zero). Then you do a magic trick with the math and cancel the infinities. This technique is called renormalization.
As a quick example, a charged object has energy from its electrical field, E = q^2 / (8 pi r). But an electron is a point particle - it has a radius of 0. So you end up dividing by zero and finding that the electron has an infinite energy (and thus also infinite mass)
So then you say that the electron itself also has a mass (a bare mass).. but when you put the numbers in divide by zero again and you find the bare mass is negative infinity.
So now you say the bare mass + electric field mass = infinity + -infinity, then wave your hands around and say the answer is 9.1x10^-31 kg:-)
I had an attempt at explaining the de sitter space:
If our universe was completely flat, with 3 ordinary dimensions of space and 1 dimension of time, then we'd call that Minkowski space, and the ordinary euclidean geometry that you learnt at school would be correct (angles in a triangle add up to 180 degrees etc)
But our universe is actually curved, like a ball, and we have special relativity. We call this space the "de Sitter space".
If the universe was curved, but more like saddle, then we would call that the "anti de Sitter space" (since a saddle curves in a way that is kinda opposite to how a saddle curves).
In mathematics and physics, n-dimensional anti de Sitter space, sometimes written AdSn, is a maximally symmetric Lorentzian manifold with constant negative scalar curvature. It is the Lorentzian analog of n-dimensional hyperbolic space, just as Minkowski space and de Sitter space are the analogs of Euclidean and elliptical spaces respectively. It is best known for its role in the AdS/CFT correspondence.
Here's my simple attempt:
If our universe was completely flat, with 3 ordinary dimensions of space and 1 dimension of time, then we'd call that Minkowski space, and the ordinary euclidean geometry that you learnt at school would be correct (angles in a triangle add up to 180 degrees etc)
But our universe is actually curved, like a ball, and we have special relativity. We call this space the "de Sitter space".
If the universe was curved, but more like saddle, then we would call that the "and de sitter space" (since a saddle curves in a way that is kinda opposite to how a saddle curves).
A computer has to remember things during its normal operation. For example it remembers what letters you've just typed so that it can display them on the screen. It remembers what the mouse cursor is at the moment, and so on. If the computer remembered all these details forever, its memory would quickly be used, so from time to time the computer has to forget all the memories that are no longer needed. If you write a document then close that document, the document is stored away and memories of it forgotten. The part of the computer software that is responsible for making sure that these memories are forgotten and making that memory available to remember new things is called the garbage collector.
I would love to have a second panel for that comic to continue from "dunno"
Scientist: "but lets find out" Scientist: "hmm, interesting it appears to predict gravity out of nowhere" Scientist: "more curious, it also appears electromagnetic forces" Scientist: "hmm, it's getting complicated, but wow it manages to fit nicely with both quantum mechanics and general relativity" Other guy: "What haven't you proved the Theory Of Everything yet? You must be crap."
Well done, an planet is not an egg. Now try to think a bit further please.
The vast majority of a planet like Venus is liquid. If you did somehow apply a suddenly torque on the surface of the planet, then think about what would happen. Play with the egg and try to think it through. And no, you can't eat a planet.
> This boundry allows for 2 different types of math to be directly applicable in the near field and in the far field.
Which doesn't help when you have something very small and very massive, so that both fields are required at the same time. For example a small black hole. The problems with the Standard Model are well known.
> You then claim I am a hyprocrite without any basis at all.
They hypocrite bit is to attack string theory because its currently not testable, then push forward another hypothesis which is also currently not testable
> Actually, that's not true. There are alternatives, including loop quantum gravity.
Quantum loop gravity is not an alternative for someone bashing string theory because of its lack of predictions, since quantum loop gravity doesn't make testable predictions either.
> String theory has been kicking around for 20 years, and essentially no progress has been made.
> I like how you conveniently forget that you have to buy a highly specialized laser printer and transparencies to accomplish that.
Hmm? No people have done on it a 300DPI printer with bog standard transparencies. You can even download the source code and do it yourself if you want: http://www.corticalcafe.com/prog_CGHmaker.htm
> And the "display a hologram on a TFT is completely ridiculous. I assume you're talking about this [siggraph.org] A few nvidia supercomputers running 65 projectors into a screen? Yup, feasible.
I've done it on a 1024x768 LCOS. Admittedly the hologram isn't going to be very big at all, but it still has many uses. For example displaying moving points of light.
Slashdot Mirror
Actually concave would also be a de Sitter space. Concave is just like convex - just looking it from the other side. If you take any point on a convex or concave shape, you'll see it curves in the same way in every direction. But a saddle curves up in one direction and down in the other direction. That's what makes it anti de sitter
> Well, it helps by ensuring that less energy is wasted pursuing it. See?
So... basically you'd call a halt to all theoretical physics since none of the current new theories are currently testable, and won't be without further investigation.
If you can prove that string theory isn't ever going to be testable, then you can win a nobel prize.
If you are arguing that it's not possible to test it at this very moment, then you should support trying to improve on it, so I don't see how calling it not science helps anything.
(Just to add, if you want to read more about renormalization, see http://en.wikipedia.org/wiki/Renormalization )
I don't know if you're just making a weak joke or if you're actually making a brilliant joke because that's exactly what does happen.
Basically you end up with a whole bunch of terms that are infinity (like from trying to divide by zero). Then you do a magic trick with the math and cancel the infinities. This technique is called renormalization.
As a quick example, a charged object has energy from its electrical field, E = q^2 / (8 pi r). But an electron is a point particle - it has a radius of 0. So you end up dividing by zero and finding that the electron has an infinite energy (and thus also infinite mass)
So then you say that the electron itself also has a mass (a bare mass).. but when you put the numbers in divide by zero again and you find the bare mass is negative infinity.
So now you say the bare mass + electric field mass = infinity + -infinity, then wave your hands around and say the answer is 9.1x10^-31 kg :-)
I had an attempt at explaining the de sitter space:
If our universe was completely flat, with 3 ordinary dimensions of space and 1 dimension of time, then we'd call that Minkowski space, and the ordinary euclidean geometry that you learnt at school would be correct (angles in a triangle add up to 180 degrees etc)
But our universe is actually curved, like a ball, and we have special relativity. We call this space the "de Sitter space".
If the universe was curved, but more like saddle, then we would call that the "anti de Sitter space" (since a saddle curves in a way that is kinda opposite to how a saddle curves).
In mathematics and physics, n-dimensional anti de Sitter space, sometimes written AdSn, is a maximally symmetric Lorentzian manifold with constant negative scalar curvature. It is the Lorentzian analog of n-dimensional hyperbolic space, just as Minkowski space and de Sitter space are the analogs of Euclidean and elliptical spaces respectively. It is best known for its role in the AdS/CFT correspondence.
Here's my simple attempt:
If our universe was completely flat, with 3 ordinary dimensions of space and 1 dimension of time, then we'd call that Minkowski space, and the ordinary euclidean geometry that you learnt at school would be correct (angles in a triangle add up to 180 degrees etc)
But our universe is actually curved, like a ball, and we have special relativity. We call this space the "de Sitter space".
If the universe was curved, but more like saddle, then we would call that the "and de sitter space" (since a saddle curves in a way that is kinda opposite to how a saddle curves).
A computer has to remember things during its normal operation. For example it remembers what letters you've just typed so that it can display them on the screen. It remembers what the mouse cursor is at the moment, and so on.
If the computer remembered all these details forever, its memory would quickly be used, so from time to time the computer has to forget all the memories that are no longer needed. If you write a document then close that document, the document is stored away and memories of it forgotten. The part of the computer software that is responsible for making sure that these memories are forgotten and making that memory available to remember new things is called the garbage collector.
There you go.
I would love to have a second panel for that comic to continue from "dunno"
Scientist: "but lets find out"
Scientist: "hmm, interesting it appears to predict gravity out of nowhere"
Scientist: "more curious, it also appears electromagnetic forces"
Scientist: "hmm, it's getting complicated, but wow it manages to fit nicely with both quantum mechanics and general relativity"
Other guy: "What haven't you proved the Theory Of Everything yet? You must be crap."
But somehow they all know about the CIA drug smuggling.
Well done, an planet is not an egg. Now try to think a bit further please.
The vast majority of a planet like Venus is liquid. If you did somehow apply a suddenly torque on the surface of the planet, then think about what would happen. Play with the egg and try to think it through. And no, you can't eat a planet.
Oh I get it - you think that because it was someone that you like that they should be allowed to do illegal things.
How is that any different to said terrorists just dialing 999 and reporting some false bomb in North London? Should we close down the phone lines too?
So basically you're against all form of police questioning, since witnesses can just lie?
And how is your example any different to just calling 911/999 and telling the police a lie? Are you saying that we should close down 999 as well?
What exactly is wrong with reporting a crime that your neighbor did?
How is that any different to doing that then posting the 'evidence' to the police?
> rotations of planets don't just 'stop momentarily'. once stopped, it stays stopped
Take a raw egg and spin it. Then stop it suddenly and then release. The egg will start spinning again.
Thousands of smaller lumps would have a massively larger surface area, so wouldn't they fall a lot faster? So within a year or so they'd be gone, no?
> This boundry allows for 2 different types of math to be directly applicable in the near field and in the far field.
Which doesn't help when you have something very small and very massive, so that both fields are required at the same time. For example a small black hole. The problems with the Standard Model are well known.
> You then claim I am a hyprocrite without any basis at all.
They hypocrite bit is to attack string theory because its currently not testable, then push forward another hypothesis which is also currently not testable
> Neither quantum nor relativity require these extra dimensions to be testable
Right, but since they contradict each other, they clearly aren't the right answer. Something more is needed.
> There appears to be some good work coming out recently that has accepted that time is not a dimension at all
And this is testable, today? If so, I'd love to hear of it. If not, then you're a hypocrite.
You keep stating that string theory is unprovable by design. If you can prove this, you'd win a Nobel prize.
> an untouchable, unverifiable ... untestable .. theory
Again, if you can prove that it is, and always will be, unverifiable and untestable, then do so.
You really should clear up your misunderstanding about this.
> If any 1 person has a theory on their own that is inherently unprovable
If you can prove that its inherently unprovable then you can win a noble prize. The rest of your post is garbage based on this misunderstanding.
There are no alternative theories that are testable. So are you seriously suggesting that there should be no funding at all for modern physics?
> Actually, that's not true. There are alternatives, including loop quantum gravity.
Quantum loop gravity is not an alternative for someone bashing string theory because of its lack of predictions, since quantum loop gravity doesn't make testable predictions either.
> String theory has been kicking around for 20 years, and essentially no progress has been made.
Lol
> I like how you conveniently forget that you have to buy a highly specialized laser printer and transparencies to accomplish that.
Hmm? No people have done on it a 300DPI printer with bog standard transparencies. You can even download the source code and do it yourself if you want: http://www.corticalcafe.com/prog_CGHmaker.htm
> And the "display a hologram on a TFT is completely ridiculous. I assume you're talking about this [siggraph.org] A few nvidia supercomputers running 65 projectors into a screen? Yup, feasible.
I've done it on a 1024x768 LCOS. Admittedly the hologram isn't going to be very big at all, but it still has many uses. For example displaying moving points of light.
Btw my PhD thesis is on this :-D You can read it if you want:
http://adsabs.harvard.edu/abs/2009arXiv0902.0551T