Curvature is not "measured with respect to [an embedding] space". If you have a triangle and the sum of the angles is not 180 degrees that's a non-Euclidian (curved) space.
But that's not how the word "curved" is used in everyday life. Call it non-Euclidian if it's non-Euclidian. Redefining common words only leads to confusion.
Participating in a discussion about an article titled "the quantum source of space-time" to say that basic concepts are nonsense because some words do not have the same meaning as in everyday life also leads to confusion.
"Entanglement lets the measurement of one particle instantaneously determine the state of a partner particle, no matter how far away it may be" No. No! No!!! This meme has really got to die. A measurement of one entangled particle does NOTHING to the other particle. Its state is exactly the same as it was before. In fact, the whole concept of "before" and "after" a remote measurement doesn't even make sense because i…
You are asserting something as true that is actually under dispute. Whether the state of the particle was already determined is the million dollar question. Importantly, under non-local theories, it doesn't have to be. Superpositions can be real and not just mathematical entities.
It's only disputed by people who haven't actually looked at the math.
And I didn't say the state of the particle was already determined. It wasn't. Yes, of course superpositions are real. Yes, of course the Bell inequalities are violated. Yes, this eliminates all local hidden variables theories. Yes, it seems like this necessarily leads to the conclusion that there is spooky action at a distance. But that's wrong. To see why, read the paper or watch the video.
The concept of "curvature of space" is obvious nonsense because curvature is measured with respect to space. This is not really true. If you take a flat two dimensional space, a sheet of paper, this space has no intrinsic curvature. You surely now imagine this sheet of paper laying flat on a table in front of you embedded in our usual three dimensional space. Now pick it up and role it to form a cylinder. This gives…
"Extrinsic curvature" is normally called just "curvature". "Intrinsic curvature" isn't normally called anything because it has minimal relevance to everyday life. If you talk about "curvature of space" the natural assumption is that you mean extrinsic curvature.
But in general relativity extrinsic curvature is the irrelevant thing, it's all about intrinsic curvature. We don't think of space-time being embedded in a higher dimensional space but we still talk about curvature of space-time, its intrinsic curvature.
These demonstrations with balls rolling on a stretchable rubber sheet to visualize gravity are really misleading in this regard because they use a good deal of extrinsic curvature to make things work but in reality mass doesn't deform space-time into a fifth dimension or at least it doesn't necessarily do so.
This message clarifies what you mean. But you said before "A measurement of one entangled particle does NOTHING to the other particle. Its state is exactly the same as it was before.". By measuring (one of the particles in) the system you are collapsing its wave function. Doesn't that mean the state of the system (both particles) is affected?
No. Collapse doesn't actually happen. Collapse is an approximation to the truth. It's a very (very!) good approximation for systems with a large number of mutually entangled degrees of freedom, but it is an approximation nonetheless. See the links I pointed to earlier to understand why.
Doesn't "the truth" involve any change in state at all? I'll look at your answer to quantum mysteries when I have time. But I suspect your original comment could have been phrased "the standard interpretation of quantum mechanics has to die"...
Here's a recent lecture by Erik Verlinde in which he tries to explain both dark energy and dark matter using entropic gravity: https://www.youtube.com/watch?v=PSYXt3Xu3xI I'm not a physicist, but he seems to be invoking similar ideas to Raamsdonk: that spacetime and gravity are emergent properties that boil down to entanglement somehow. But the loop quantum gravity people have been saying something like that for ages…
I am a physicist... The most interesting (to me, at any rate) bit of this article are susskind's observations on computational complexity. As a precocious undergrad I put forward the idea that gravity and time dilation were the same thing, and both stemmed from the universe needing a constant amount of "time" to compute the interrelations between the particles in a volume of space - and if there were more particles m…
This is a fascinating idea. Could you elaborate on how you think the additional computational complexity would give rise to attraction between particles in matter-dense regions?
Here's a recent lecture by Erik Verlinde in which he tries to explain both dark energy and dark matter using entropic gravity: https://www.youtube.com/watch?v=PSYXt3Xu3xI I'm not a physicist, but he seems to be invoking similar ideas to Raamsdonk: that spacetime and gravity are emergent properties that boil down to entanglement somehow. But the loop quantum gravity people have been saying something like that for ages…
I am a physicist... The most interesting (to me, at any rate) bit of this article are susskind's observations on computational complexity. As a precocious undergrad I put forward the idea that gravity and time dilation were the same thing, and both stemmed from the universe needing a constant amount of "time" to compute the interrelations between the particles in a volume of space - and if there were more particles m…
Why does it imply a simulation? Perhaps it can be explained by an anthropic argument: Perhaps the kind of mechanics behind spacetime in which time evolution is computed in a stepwise manner depending on density are extraordinarily more likely because they somehow allow for much simpler mechanics (sets of laws with lower entropy are more likely to be the ones we find ourselves in, especially so if we assume that all non-physical sets of laws are realized as well, so that the impact of such a difference in entropy on the probabilties could be vast).
Here's a recent lecture by Erik Verlinde in which he tries to explain both dark energy and dark matter using entropic gravity: https://www.youtube.com/watch?v=PSYXt3Xu3xI I'm not a physicist, but he seems to be invoking similar ideas to Raamsdonk: that spacetime and gravity are emergent properties that boil down to entanglement somehow. But the loop quantum gravity people have been saying something like that for ages…
I am a physicist... The most interesting (to me, at any rate) bit of this article are susskind's observations on computational complexity. As a precocious undergrad I put forward the idea that gravity and time dilation were the same thing, and both stemmed from the universe needing a constant amount of "time" to compute the interrelations between the particles in a volume of space - and if there were more particles m…
Beautiful stuff, man. One of the more interesting questions I've seen asked in my casual hobby readings lately is: "Is the Universe quantized?" Meaning of course, is there a final limit to how small things get, and, with the passing of time, does it flow freely or pass in very tiny quantized periods?
Sorrt, but you're flat-out wrong, and the sources you link aren't credible. (That's not even a journal paper.) I suggest you read Scott Aaronson's explanation of why you're wrong (he understands this better than me): http://www.scottaaronson.com/blog/?cat=33
Here's the credible citation: http://arxiv.org/abs/quant-ph/9605002 (It's ironic, BTW, that you should complain that my citation is "not even a journal paper" when yours isn't either.) And BTW2, Aaronson's blog post doesn't contradict my position. The Bell inequality violations are indeed real. They just aren't caused by "spooky action at a distance." They are caused by the classical correlations that arise when you…
>It's amazing how the Physics world bifurcates into two camps: those who think that the connection between entanglement and measurement is common knowledge, and those who adamantly deny that it is true.
The fact that there are two legitimate camps means that no one knows for sure what is happening. And you are obviously in one of those camps. So to insist the world is a particular way is to deny how much is still unknown and acknowledged by others in the physics community.
"The theory holds that gravity is geometry: particles are deflected ... not because they feel a force ... but because space and time around the object are curved." Can anyone explain to me why it can't simply be a force? If you accept that gravity is caused by energy and not mass (which is obviously the case), then I see no reason a photon can not experience a force. So what is the reason to insist it's geometry? And…
Good questions. It could be a force - if someone finds a theory that describes all the observational data. They haven't. The reason to insist geometry is that general relativity manages to predict extremely accurately the result of all gravitational experiments/observations as of 2015. In science, prediction comes before explanation, meaning if you have to accept whatever explanation the best predictive theory offers…
" In science, prediction comes before explanation"
I'm going to be a little picky about your choice of language here.
It seems to me that, at least that your are predicting randomly, you can't possible make predictions with a good model, that is, a good explanation.
What do you mean by that? (Obviously you don't mean necessarily literally on paper) Do you claim that the predictions that are made about what is observed are false, or that the interpretation is wrong, or? Surely you don't mean that by interpreting it in a particular way, it causes different things to happen, so I can't think of anything other than those two.
I think he means that the "entanglement" as understood by general public, i.e. as "I do something to particle A, and suddenly particle B changes" is an invalid way of reading the math; you didn't do anything to B, you merely figured out, by interacting with A, in which world you're in.
You see, this is the thing that kills me when thinking about the quantum world. The Many Worlds interpretation is so clean and obvious, except for one thing - it requires creating a new universe for each quantum entanglement event. Gah!
Of course that does make me think about forking processes and copy-on-write, and the idea that our reality is just a simulation in a computer and that maybe creating new universes is not as expensive as we might at first think...