andrew s

QM is a generalised probability theory. The simplest is the one where the "amplitudes " or probabilities sum to one. The next is where the sum of the squares of the "amplitudes " sum to one. This is QM. What Bell showed is that it can't be replicated by a local hidden variable theory with the first type of probability. An example would be a red and green sock each put in a box and separated. On opening one you box know instantly what the result of opening the other would be. You can't do this for QM systems. There are not hidden variables like sock colour. I am not arguing time evolution does not happen in a continuous way. All I am maintaining is that predictions of probability is not the same as being deterministic. Saying a coin will land 50/50 heads/tails is not being deterministic. Being correct 100% of the time in saying the next tossing will give a head and it does or tail and it does is. Regards Andrew

Which supports what I said it only predicts probabilities. To be deterministic it has to predict when it will decay. As mentioned previously not all quantum systems have a wave function and so Schrodingers equation can't be used you need a more general theory. The Pauli matrices for electron spin are an example. Schrodingers cat is a nonsense no macroscopic object can be in such a superposition the interaction with the air it needs to breathe will almost instantaneously decohere it to one state or the other. (Or failing that the CMB will do it just as quickly.) Schrodinger proposed it because it was a nonsense in his view. Regards Andrew PS all the interesting things in QM happen at the point of "measurement " when Schrodingers equation no longer applies. It is still a mystery - the measurement problem is one outstanding problem in the foundations of physics.

Off to play badminton and I predict I will lose most of my matches to much younger opponents. 😊 Regards Andrew

No for the photon you can just calculate the probability of emissions and similarly for the nucleus and QCD. Regards Andrew

Yes in classical mechanics no in QM. There are no deterministic equations for the disintegration of a radioactive nucleus or for the spontaneous emission of a photon from an excited atom. Regards Andrew

So I prepare a dice with 6 up. No matter how often I measure it is stays at 6 (unless I disturbed it). This seems quite normal to me. As I understand it branching only occurs when the probability is not 100% Regards Andrew

Yes but they are not of the initial conditions + differential equation form which you claimed were the basis of our physics. That was the point I was make here. Regards Andrew

@vlaiv we will have to agree to differ. I don't view the state function as real in the way you do. In your world reality lies in a potentially infinite rigged hilbert space. In mine it sits in 4d spacetime. In many world all potential possibilities exist so you went to the pub in one world and in another you did not. 😊 Regards Andrew

But for large system we can't meet your conditions that's why all physical theories revert to course graining. That's what I was pointing out. We can do it that way but don't have to hence Largrangian and Hamiltonian mechanics and principle of least action. In QM you prepare a state (spin up) if you measure it for up or down you get spin up 100% but if you measure at a different angle you can only predict probabilities of less than 100%. In this sense it is not deterministic. Regards Andrew PS not all systems have a wave function (electron spin is one) and you have use matrix mechanics which has no concept of deterministic evolution.

Not if you believe in the "block" Universe. It all exists but we just experience it a moment at a time. Of course Physics doesn't claim to be correct just good at predicting things in the scope of its theories. To be honest I don't understand your initial post on this. However, on determinism there are never exact initial conditions due to QM and even if there were the large number of degrees of freedom means any pretense at prediction is all but impossible. Take a simple example. You can't even in principle say if a photon from a star will hit a particular spot on your CCD detector only the probability of it happening. Once it has arrived the arrival time of the next is only statistically predictable as is the total number of hits in a given time. There are some 86 billion neurons in the brain and many more interconnects. We have no physical theory of it's emergent properties e.g. consciousness. Regards Andrew

Apart from the detection of the Higgs boson and gravitational waves, which were expected, there has been no new clear cut experimental results for theorists to get their teeth into other than dark matter and dark energy. The failure to find dark matter particles leaving both dark energy and matter hanging theoretically and the continuing inability to reconcile general relativity and QFT has left physics with two very good theories and no clear path forward. We need some genuinely novel experimental results to lead theorists out of their mathematics and back to reality (whatever that is). Regards Andrew

I don't think so. A vertical obstruction produces a horizontal diffraction line. In reality the pattern is more complex but it shows the brightest features. Regards Andrew

Yes they did. They will have modelled the effect of the hexagonal mirrors and the secondary support. Regards Andrew

Lot of people are like that too. Regards Andrew

Yes but... ...your not going to like the answer. 42 Regards Andrew

Is the sun's gravity so strong they can fly upside down ? 😊 Regards Andrew

You will need to find the relevant peer reviewed paper. It will have the relevant error bars. However, it s very difficult to calculate systematic errors and all "cosmological " distances rely on what cosmological model you accept. One advantage of the LCDM cosmology is the it is easiest to apply. Regards Andrew See @Gfamily's post above.

I think you'll find it is calculated based on the measured angular dimensions and red shift using models of the gravitational lensing and the LCMD cosmology . Regards Andrew

Photons don't have a reference frame. If they did they would be a rest in it? 😊 Regards Andrew

Not sure this has any impact on coronal heating. In star formation deuterium ignites first before hydrogen. In any case it would tend to migrate to the core where it would be converted to helium. Regards Andrew

They could just be fainter spikes from the arms which are not normally visible. The full diffraction pattern is quite complex. Regards Andrew

As far as we can tell the Universe is not moving in any direction. However, everything on average (I.e. not gravitationally bound) is moving apart. Just as spots on the surface of a balloon as you blow it up. Regards Andrew

@MalcolmM this is the derivation I was looking for. http://www.adamauton.com/warp/emc2.html Regards Andrew

While the ambient temperature may not require cooling regulation of the temperature to a given value makes it easier to apply darks, flats etc. Regards Andrew

Try this then Regards Andrew