Slashdot Mirror
New Theory of Gravity Decouples Space & Time
eldavojohn writes "Petr Horava, a physicist at the University of California in Berkeley, has a new theory about gravity and spacetime. At high energies, it actually snips any ties between space and time, yet at low energies devolves to equivalence with the theory of General Relativity, which binds them together. The theory is gaining popularity with physicists because it fits some observations better than Einstein's or Newton's solutions. It better predicts the movement of the planets (in an idealized case) and has a potential to create the illusion of dark matter. Another physicist calculated that under Horava Gravity, our universe would experience not a Big Bang but a Big Bounce — and the new theory reproduces the ripples from such an event in a way that matches measurements of the cosmic microwave background."
Special relativity, of course, forbids sending information faster than light. A theory supplanting the space-time unification of General Relativity would also supplant special relativity, and hence might not have that limitation. Here's an inteersting tidbit from the article: "Gia Dvali, a quantum gravity expert at CERN, remains cautious. A few years ago he tried a similar trick, breaking apart space and time in an attempt to explain dark energy. But he abandoned his model because it allowed information to be communicated faster than the speed of light."
I'd call that a feature, not a bug!
http://www.geoffreylandis.com
Behold, science.
The catch is, eventually one will be right, and explain things that are out of the scope of Einstein's theories or more accurately explain in-scope things.
Or do you believe we are at the pinnacle of the field, and can achieve no more?
Self proclaimed typo king, and inventor of the bear destroying coffee table (patent not pending).
We have reached enlightenment. We shall now call ourselves Q.
(huuummmm)
Man this is dull.
"I disapprove of what you say, but I will defend to the death your right to say it." - historian Evelyn Beatrice Hall
Horavec's formulation works for certain (perfectly spherical) cases of the stress-energy tensor, not in other cases. In fact it produces some wildly inaccurate results in more realistic cases. Nor is he the first to try this kind of thing. Still, it sounds interesting and further refinements could produce a fully consistent theory which can match observation. When and if that happens then it will be a really major advance. It certainly seems like we're edging closer to something.
"Malo periculosam, libertatem quam quietam servitutem." -- Jefferson
Does this theory suck or is there some pull to it? It just seems so weighty to me.
Help save the critically endangered Blue Iguana
So does this compete with string theory or have a chance modifying it to an eventual theory of everything?
I believe they will all be right, but it will only be from the perspective of the observer/believer which is right at the moment. However when it isn't being observed it will be both right and wrong until observed again. Therefore there are multiple pinnacles and it won't matter which are right or highest. Just have your towel ready because on top of the pinnacle is a little man who is only going to apologize for the inconvenience.
Always have a towell ready.
*Repent!Quit Your Job!Slack Off!The World Ends Tomorrow and You May Die!
It's a PDF version of a PowerPoint deck, so it's not exactly easy to read.
Indeed, informative link but I think your signature should be at the start of your post. I was doing pretty good right up until they plugged the ansatz into the Horava’s action to produce the reduced Lagrangian.
My work here is dung.
Yeah: http://yfrog.com/b9sciencevsfaithbigp
This sentiment is rather old, I'm sure before and when Einstein came about, people were saying the same thing about Newtonian physics. Skepticism about new theories are fine, but I'm sure the science will come to a point where we do discover something better than Einstein's formulas in some areas.
BTW, my physics is really rusty, doesn't one of Einstein's equations devolve into a newtonian equation at slow speed? Which just shows that things are truly built on top of one another.
To differentiate myself from the lot of you bores I shall take a first name: Fah. From this point on I am Fah Q! :)
We have always been at war with Eurasia!
If you reverse the polarity, inject some chroniton particles, and rub Patrick Stewart's head for good luck, it'll still work.
Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
... until they plugged the ansatz into the Horava’s action to produce the reduced Lagrangian.
Huh. I didn't get that far. And I'm pretty sure that whatever it that is, it's illegal in Texas.
1. Gravity is still spooky action at a distance with no causal mechanism defined.
2. I don't think time, as in "time lines" or some kind of unidirectional movement through a medium exists. Now exists, hypostatized out of a past (which stops existing when it stops being now) and which in turn hypostatizes the future (which does not exist.)
3. Electromagnetism is the dominant force in the heavens as it is on Earth.
4. Stars are organisms and they reproduce through fission.
5. Galaxies are powered by vast electric circuits; beads on a string.
When a true genius appears, you can know him by this sign: that all the dunces are in a confederacy against him.
Yet, who is Petr Hoava? He maintains a Web page that offers the following biography.
"Petr Horava received his Ph.D. in 1991 at the Institute of Physics of the Czech Academy of Sciences in Prague. He was awarded the Robert McCormick Research Fellowship at the Enrico Fermi Institute at the University of Chicago, worked as a Research Associate at Princeton University, and won a Sherman Fairchild Senior Research Fellowship at Caltech, before joining the New High Energy Theory Center at Rutgers University in 2000 as an Associate Professor. In 1997, he was awarded the Junior Prize of the Czech Learned Society, and in 1999 he appeared on the list of top three scientists of the Czech Republic of the 90's. He joined the Physics Department at UC Berkeley in 2001."
The liberation of Eastern Europe in 1989 has unleashed an intellectual force that will advance human knowledge by leaps and bounds. 2009 is the 20th anniversary of that liberation.
Buddha bless the Eastern Europeans.
This is healthy. Science can only progress if we accept that thinking outside the box is admissable. If the idea works ehen it will be testable.
Facts are history now plebs have politics for religion on social media.
You fixed it by misspelling General Relativity?
Or maybe you actually meant the theory would be better than 'Reletivity'. That could work.
http://www.chaotickingdoms.com
BTW, my physics is really rusty, doesn't one of Einstein's equations devolve into a newtonian equation at slow speed?
Wouldn't be correct if it didn't. Newton wasn't *wrong*, he just didn't specify the parts he couldn't see. Same with Einstein, same with this.
Yep. It's called the Correspondence Principle when applied to quantum/classical mechanics. Basically, Newton's equations 'fall out' of Einstein's when you assume the speed of light is a big number relative to all other speeds.
Recently, paradigms in physics have been interesting in this respect as the new perfectly subsume the prior in their limits. I am not sure that this is a tautology of science, but it is an elegant means of progression.
Wrong.
Special relativity is built on two principles:
(actually, if you take Maxwell's equation into account, the first is just a special case of the second). Especially it does not postulate that there's nothing faster than light. Rather,
However, you can describe hypothetical faster-than-light particles in SRT (so-called tachyons; those cannot be decelerated to below the speed of light), and AFAIK there have been experiments to look for them. Note however that as soon as you add quantum mechanics to the picture, even with tachyons no information can be transmitted faster than light (local disturbances in he quantum tachyon field only propagate with light speed).
General relativity adds the equivalence principle (locally you cannot distinguish between gravitation and acceleration) and the demand of general covariance (the equations must look the same regardless of choice of coordinates, even if those don't correspond to an inertial system).
The Tao of math: The numbers you can count are not the real numbers.
Then I shall be Fah Q 2!
.evom ton seod gis eht
Same thing in Quantum Mechanics. They devolve into classical equations, if you set Planck's Constant to 0.
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
What, science?
I swear to God...I swear to God! That is NOT how you treat your human!
Well Fah Q both then
Cousin to Sofa King Awesome, I suppose. You people are so immature.
I don't understand this, I don't need faith to believe there is order in the universe. It's been proven that there is a certain amount of order and I can reproduce those measurements if I wanted to see for myself. Causality is equally provable. We don't know how everything works yet but the stuff we are sure about I don't need faith to believe. The other stuff we make our best guess while reserving the right to change our mind pending further data.
Then we need a new theory.
Well, "the same in all systems" in the post above didn't refer to "at different places in the universe", but "as seen/described by different observers in the same part of the universe".
That doesn't mean we don't also assume that the laws of nature are always and everywhere the same. Indeed, that's basically always assumed.
By applying the laws we found locally to observations of distant objects, and seeing if they fit. For example, we can look at the spectra of distant stars and look if we get the same atomic spectral lines as on earth. This works great; so we know that atomic physics obviously works the same in distant stars. Also we can observe the 21cm hydrogen line everywhere in space, so atomic physics seems to apply also in between the stars.
Where we do have some problems is with large scale gravitation (what we describe with dark matter and dark energy). However, the local effects of those deviations are small enough that we couldn't measure them directly anyway, so it's also no evidence that the local laws of physics are different than the distant ones, even if those effects are to be described with modified theories.
No, it's much too small for that. To be an indication for different physics "outside" it would have to be such a large deviation that we would have to have detected the difference if it applied to Earth.
The Tao of math: The numbers you can count are not the real numbers.
Spooky action at a distance doesn't need any finagling to get around lightspeed, because spooky action at a distance doesn't involve any communication. It's already compatible with general relativity (at least, insofar as any quantum theory is compatible with relativity).
A flawed, but illustrative example that should explain why this is so: imagine you have a friend who is flipping a coin... if it comes up heads, he writes an X on two sheets of paper, if it comes up tails, he writes a checkmark on both instead. Both are immediately sealed inside envelopes and mailed to opposites sides of the planet. If you open one letter and see an X, you instantly know the other has an X also. That doesn't require any communication.
A slightly less flawed, and still illustrative extension: Now instead of a coin flip, you have a machine do it based on the decay of a mass of cesium, and you have a perfect envelope which protects against quantum decoherence. The same situation applies, as soon as you open one envelope you know what is contained in the other. The only difference this time is that the letters were entangled and in a superposition of states. However, it's the same mechanism, and no communication is required.
I'm not familiar with this Jesus theory. Because I am open to outside-the-box thinking, I am willing to give you the benefit of the doubt and evaluate your theory based on it's merits, rather than dismissing it out of hand. Can you send me an example where Jesus accurately predicts known experimental results? Also, what experiments would you posit to prove or disprove Jesus? I eagerly await your reply.
Not so. You cannot prove that repeatedly making a measurement in the past is any indication that it will hold in the future. Pointing out that it's worked before is just begging the question, and therefore reproducing the results doesn't help, for it does not mean you'll reproduce the results *again*.
You *must* presuppose that the future is relevantly like the past for empiricism to have any meaning in any context; it's pretty much an irreducible problem.
With that said, such "faith" is, I would argue, essentially to daily living and doesn't really deserve to be categorized as "faith" except in the most pedantic of senses. Without acting under this presupposition, you cannot learn. Anything. I suspect that biologically this presupposition cannot be unlearned since it appears to be intrinsic to learning even in some of the stupider members of the animal kingdom.
No one is questioning the intelligence of the soviets or eastern europeans. The problem was that when they did science, they did it in an inverted way. For example, in Soviet Russia, the particles accelerated you.
Fah Q and the horse you rode in on?
"You cannot prove that repeatedly making a measurement in the past is any indication that it will hold in the future."
Flip side, you can't prove that it won't hold true in the future either. In essence, your argument is a case of argumentum ad ignorantiam.
The bottom line is that you're engaging in fancy footwork trying to get to him to use the word "faith", in which case you then have a basis for moving on to a discussion of "true faith", a belief in God or some such. Faith is belief without proof.
But... if you have proof then you don't need faith. Past personal observation, history, science, math, and orbital mechanics all say that the sun will come up tomorrow. Faith is not needed.
Any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so.
"Faith is belief without proof."
Belief without evidence is called blind faith, science rests on the faith that the universe is ultimately predictable and will continue to exist even if we don't (in other words it believes that the proverbial tree in a forest does indeed make a noise).
There is no way to "prove" that the universe behaves like this but rational people take it as an indisputable fact because the evidence of ones own perceptions is very difficult to ignore particularly when they match the perceptions of other humans. So yes, science is based on faith as is all knowledge that goes further than "I think therfore I am".
"The bottom line is that you're engaging in fancy footwork trying to get to him to use the word "faith"
No he is not, the "bottom line" is that basic scientific philosophy confuses the hell out of people who subscribe to the popular but incorrect notion that science is in the bussiness of "proof". We wouldn't even be having this discussion if epistemology was taught in modern high schools.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
Can you send me an example where Jesus accurately predicts known experimental results?
(I'm not sure if your stay on rejection was genuine or troll-bait, but it's caught momentum and I thought I'd provide an honest response rather than leave the question hanging.)
There's the golden rule, for starters. He didn't invent it, but he was instrumental in the widespread use of its positive statement ("Do unto others as you would have them do unto you" as opposed to "Do not to your neighbor what you would take ill from him"). And the result of following that rule, the rule of initiating kindness, you are statistically more likely to be treated kindly in return. Common sense and anecdotal evidence bear this out as well.
Then there's a bunch of other stuff he said, including things about the Kingdom of Heaven being here and now, forgiveness, faith, and love, that has unfortunately been so steadily downplayed and cloaked in tradition and dogma that it gets lost in the "war" to "win souls" for God. I think the historical Jesus would get along just fine with good-hearted atheists, Muslims, Hindus, Krishnas, Christians, Buddhists, and followers of most any other creed that you can imagine--and he probably had more in common with the Buddhists than we tend to think. He might not agree with all of the beliefs in those various systems, but he was more interested in disciples, people who would emulate his way of living, than converts to his religion, which didn't even exist during his lifetime. In other words, I think he'd be an excellent person to discuss philosophy and religion with, and he'd probably be the first to quell any budding flame wars.
This is of course only my understanding of Jesus. I've put a lot of thought and a decent amount of study into it, so I have a nuanced view not shared by most Christians, but I prefer to simply act in a manner I think he would approve of than to talk about it. It's more challenging and more effective to act, and I lack the agenda to convert people so dislike being perceived as having it. It is still disheartening to see his teachings rejected out-of-hand because of the centuries of stupid, un-Christlike actions of his followers, not to mention the (in my opinion) corruption of his words within the Bible. I hope to change that by trying to live up to the way I think he did. Even if most people who learn from me never find out my source, it is a good way to live.
Your brain is not a computer.