elektropionir

It is just weird that papers like this can be published. "Deep learning signal prediction effectively eliminated EMI signals, enabling clear imaging without shielding." - this means that they have found a way to remove random noise, which if true, should be the truly revolutionary claim in this paper. If the "EMI" is not random you can just filter it so you don't need what they are doing. If it isn't random, whatever they are doing can "predict" the noise, they even use the word in that sentence. They are claiming that they can replace physical filtering of noise before it corrupts the signal (shielding) with software "removal" of noise after it has already corrupted the signal. This is simply not possible without loss of information (i.e. resolution). The images that they get from standard Fourier Transform reconstruction are still pretty noisy so on top they "enhance" the reconstruction by running it through a neural net. At that point they don't need the signal - just tell the network what you want to see. The fact that there are no validation scans using known phantoms is telling.

The reason why they know about it at all is because it was tracked using military equipment designed to track potential threats in the air. They know the trajectory of the fireball with very high accuracy and they can model where exactly it impacted the ocean.

Here is a talk in which he mentions specific experiments:

https://youtu.be/LGd8p-GSLgY?t=3512

This is a fairly old talk and if you do a bit more digging I think he has other talks with more experiments.

I don't think there is consensus that decoherence = measurement. This is a sophisticated experiment that controls the level of position information being "radiated" to the environment. But Born's rule and the measurement postulate are still baked into the fact that you are then measuring the interference pattern.

One thing I never quite understood about the decoherence argument for resolving the measurement problem is that it forces the "collapse" to happen with local interactions. This of course makes sense since you want to think of a measurement as a "normal", unitary process. This means the environment has to "enact" the projection operator through interactions. If you have the most basic EPR pair, how can this happen? How can you decohere the wave function of the spacelike separated counterpart (B) by locally measuring the other spin (A) and then letting the environment project out the state of B through local interactions? In this experiment https://arxiv.org/pdf/1511.03190.pdf they have two detectors 60 meters apart in a subbasement of a castle. What are the interactions in those hallways that are carrying the correlation from the decoherence/measurement on one side of the experiment to the other, faster than light to maintain the correlations. This seems too basic of a question so I don't know if I'm just missing something obvious, but to me it seems like a pretty straightforward argument that the collapse cannot happen through decoherence. I've only dug out one random paper that mentioned this argument with very little subsequent referencing of it.

How do you know it would be the same? That's an assumption. The measurement problem is a problem because quantum mechanics postulates two types of processes "normal" unitary evolution and "measurements" that project out the wave function into eigenstates of the measured operator. This is obviously inconsistent since there is no definition, formal or operational of what process is a measurement and what process isn't a measurement. How do you know that your measurement apparatus isn't just evolving unitarily (which is what you would expect if it was a "normal" system) until someone looks at it to read out the results. Consciousness enters only in the fact that for anyone to know what happened to the experiment someone has to do the readout (otherwise you're just writing equations). At the point of readout you can't tell who or what did the collapse.

Consciousness comes indirectly into quantum mechanics through the measurement postulate. You have to assume something special about measurement which breaks unitarity. Not all physicist are convinced, but it is the traditional way quantum mechanics is taught (all of the "transition probabilities" are really measurement probabilities). The problem is that you can't tell if your apparatus caused the collapse or if it was you that measured the apparatus that then caused the collapse. And because you can only know that something was "observed" when a conscious physicist makes that final readout you end up with a solipsistic situation where the only thing you can be certain of is that it was that last conscious observer that could have for sure collapsed the wave function. It could be that the collapse happened in the apparatus itself but as far as I know you have no way of telling the difference between it projecting the wave function of the measured system or you projecting the wave function of the apparatus into a pointer state. Basically consciousness sneaks in through the fact that there is no definition of what constitutes a measurement - what makes one physical process a measurement as opposed to all others that are unitary and the only thing you are certain of is that final "conscious" readout should count as measurement.

They did diffusion tensor imaging. What this does, using MRI, is determine the local anisotropy of water flow in each voxel. You assume that this anisotropy aligns with with the axis of axons, since they limit the diffusion of water across their axis (water diffuses along them). You can then use the principal directions of the diffusion tensor to estimate in what direction the water, i.e. the axons are "flowing" giving you an approximate picture of how axons connect different parts of the brain.

I made notes some time ago that cover the linear algebra needed for Quantum Mechanics in some details and then go on to introduce basic QM at the end:

https://graybits.biz/notes/quantum_mechanics/preface

There are ideas for slowing them down and even returning them back to Earth, at least in principle:

http://www.centauri-dreams.org/?p=31913

Nothing that could be implemented in any foreseeable future though.

This also let you make "memory peekers". It was just a simple assembly program that would offset the pointer to a bitplane based on the mouse vertical movement. You could "look" at the RAM and it was one way to rip images since you would see the bitmaps of images from the game still in RAM after the reset.

You can't transmit information through entangled pairs. What is instantaneous is the change of the state for the whole system (the pair) after you measure one of particles. However the result of that measurement (if it's non-trivial, i.e. if the measurement actually changes the state) is fundamentally random so the only thing you would be seeing is perfectly and instantaneously correlated noise on both ends.

You're right, it's a typo, the sum was on the wrong side. I fixed the equation. Thanks for catching it. Please let me know if you find any other issues. I wrote the original notes a while ago and I had to do some adjustments to make the LaTeX source work with MathJax so there might be other typos.

BTW, |u> = u_i |e_i> would be the correct equation in Einstein notation where the u_i |e_i> would be a contraction in which the summation along repeated indices is implicit. When you're dealing with a lot of tensor multiplication this notation is very useful because of its clarity and compactness.

Submitter here. Sorry about the layout problems. I hate usability issues like these and I just did some quick fixes. Should work a bit better on narrower screens.

I was more excited about the content and getting that right that I just didn't test the layout before posting (I have large monitors so my defaults were not geared toward small screen sizes). I had an eye exam today so I could literally only now see these comments since my pupils were dilated.

I hope you can now get to some of the quantum mechanics stuff.

I think it's more likely we'll see an asteroid mining economy bringing lithium for batteries on Earth than millions of 1km holes with 20 ton weights storing energy for single charges of electric vehicles.

Whatever local (i.e. small scale) energy storage we have in the future you can probably bet (from first principles) with 99% certainty it will be based on the electromagnetic force. Gravity is too weak to be practical for smaller scale storage and cannot give mobile storage units since you have to deal with huge weights. For large scale see the "pumped storage" system already mentioned in this thread. Just for illustration, the "Taum Sauk Hydroelectric Power Station" can produce 175MW of continuous power. If you dropped the 18T weight in the 1km shaft you'd get about 13MW averaged over the 14s fall. Then you have to lift it up again if there are still enough pieces left.

Even if you found a way to store energy in nuclear interactions (i.e. "charge a nuclear battery") you don't want to have a bunch of containers full of radioactive material all over the place. If one thought it through, I wouldn't be surprised if there are in-principle issues for the charging part similar to the ones with gravity.

Since we don't know of any others, this leaves only the electromagnetic force to store energy with sufficient mass (or volume) density in practical ways. Whatever it ends up being (chemical batteries, supercapacitors or something else) the future local energy storage unit will separate and hold charges apart.

The energy density for gravity is just immensely small, that's why you need dams holding back rivers to use them to generate electricity. For a 1km hole (that's in the middle of their 500m - 1500m range) you have an energy density of 10kJ/kg of the weight that stores the energy. The energy stored in a Tesla roadster battery pack is around 50kWh which is 180MJ. This means that you need a 18,000kg weight in a 1km deep (immovable) hole to have the equivalent of a Roadster battery pack. I'd go with the battery pack.