New answers tagged

-1

@curious One stated- "A photon doesn't oscillate. the field does." A counter theory is provided that shows that mass components of a photon does oscillate and they cause the EMF behavior. https://youtu.be/xPmNDQuufqY and given on www.mono-charges.com Agree with the other frequency statements giving energy. Disagree with "There is nothing complicated ...


0

There is no "point of view of the photons", you can't attach a frame of reference to them. Best if you imagine the photons as waves, and as these waves are propagating with $c$. The classical time dilatation, length contraction formulas (you know, everywhere the $\frac{1}{\sqrt(1-\frac{v^2}{c^2})}$ in them) are defined only for macro-sized objects going ...


-3

According to the book, Feynman said that one valid interpretation is that on its way from the emitter to the photoscreen, the photon actually takes every possible path. That's right. The photon has an E=hf wave nature. It is not a point particle. Think of it as something like a seismic wave. Imagine a seismic wave travelling from A to B on a gedanken plain....


0

Apart from the 'yes' as the first word in @Daniel's answer, I think the rest of his answer is correct. EPR claimed some 'spooky action at a distance', and that it proved QM was not true. Bell's theorem and inequalities, and the experiments carried out, proved that there was no such issue, that QM does not allow a local hidden variable explanation, by ...


0

Supposing that you know well the Bell test experiments with all its devices. The Bell theorem made a QM prediction about the correlations between entangled photons. This prediction is different than the realists one. Bell expected that the realists may not do better than 50% with a full photons detection. In fact, not-canonical-QM theorists know how to ...


2

Yes - these experiments have been conducted, most famously by Aspect et al., but also by others, see Wikipedia. They all observed violations of Bell's inequalities - Our world is therefore not local-realistic in the sense of Einstein. An extension of Bell's inequalities by Legett (Legett inequalities) holds for non-local realistic theories. Their violation ...


5

I would like to add a few things to ACuriousMind's answer. What Greene most certainly intends to say is every path(even faster than light ones i.e. those which are not time-like everywhere) contributes to the propagation amplitude. In fact,since every path in space-time contributes with equal weight, there are also paths which go "back in time" and "come ...


18

The paths of the Feynman path integral are not actually taken. The phrase "takes every possible path" is a mangled statement of the mathematical instruction to take the integral of $\exp(-\mathrm{i}S)$ over all possible paths for the action $S$ to get the probability amplitude of something happening. It is a fact of quantum mechanics that this integral ...


3

As mentioned in comments, a photon is "delocalised", so it feels the whole system. You may imagine a photon as a long-long wave (to have a defined frequency) and as such it interacts with the whole material. More strictly, one can say that the source of photon is the whole set of charges, so the photon is a collective mode of excitation of a given system. ...


1

Currently, we don't even know why the laws of quantum physics exist or what they are dependent upon, we only observe their properties, their results. The "random" decay of an atom is not without cause, it's machinations are simply unpredictable, too complex to predict accurately and therefore we call them "random" but then prove they are not random through ...


4

If all truncated $n$-point functions vanish for $n>2$ (i.e. we are dealing with a so-called generalized free field), microcausality for vacuum expectation values and at the operator level are equivalent. The former, on its turn, follows from Lorentz invariance alone in the case of scalar (but not necessarily free) fields, as shown by Pierre-Denis Methée, ...


0

In quantum field theory, vector bosons are subatomic particles known as force carriers which are the quanta of their respective fields. For instance, the photon is the quanta of the electromagnetic field, thereby mediating the electromagnetic force. In particle physics, fundamental forces are seen to arise from the emission and absorption of virtual ...


1

The Einstein equations which describe general relativity do not make a difference between waves propagating forward in time and waves propagating backwards in time. Just as the Maxwell equations, which describe electromagnetism, allow both solutions for waves propagating forward in time as well as for waves propagating backwards in time. However, for an ...


1

Gravitational waves are on the same footing as electromagnetic waves - they are lightlike processes, propagating with speed of light c. For all fundamental problems concerning time, we may not forget to have a look at the corresponding proper time. The proper time of lightlike processes is zero, their spacetime interval is empty. Observers are synchronizing ...


1

I was laying awake last night thinking about this very question, there may be a way to test this by looking for a specific type of signal in something like the LIGO. This type of signal would precede the actual event that created the signal (a binary merging event 2ly away would arrive 2 years prior to the actual event occurring) and the data should be "...


3

We don't believe this is possible. The justification for this belief is nothing less and nothing more than experimental observation. We have never observed a process where an effect comes before its cause, so we simply reason inductively to establish a postulate that the preferred order of events in physical processes is always the same, for any observer. ...



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