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A Photon has no mass. It can’t rest.

A) A Photon has no mass. B) A implies “It can’t rest”. C) Therefore it doesn’t have rest mass. D) Photon rest mass is zero.

Assertion and reasoning; A is correct. B is correct and follows from A. C is correct, it does follow from B. But D is incorrect it does not follow from A, B, or C. Its erroneous, a sloppy language that has been thought to be correct for ages now.

The trick is to realize there is no property called mass of photon — at-least in the same sense as it is for other particles with mass, therefore no rest mass. To say rest mass is zero is a special value of mass or rest mass. It just doesn’t have rest mass, as it neither has mass, nor rest, which are equivalent formulations, one leads to other. But A, B or C do not lead to D. They are not equivalent way of saying each other. They invalidate each other actually.

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What happens when squirrels do not move.

Stationary state and squirrels !

Okay so the squirrel isn’t moving around so much, giving a fuzzy image. We can call the instant during which the squirrel wasn’t moving akin to a “gross” stationary state.

But why is the railing of window fuzzy? It isn’t moving !


Due to diffraction enough light is coming from the other side of the iron bar, to enable us to see whats there. That quadrangle is diffracting the light. But why its fuzzy?

Diffraction is by its own very nature even though purely classical in many sense, fuzzy towards energy if time window is small. [due to energy vs time uncertainty]

That is, full energy cycle isn’t available, because a small time window is chosen. If you time-lapse the photograph, diffraction will become quite insignificant. Although it might still be there depending on details.

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The time-energy uncertainty relation.

The time-energy uncertainty relation is a blessing in disguise which comes in handy to check various values that are quoted, so as to see if something is inconsistent or not. It’s very powerful in guiding to check if we are ourselves making something silly or not.

I have described in two recent articles — will link later, why.

1. One must be careful what energy and what time one is relating to, one just does not take any time and any energy and make a relation, in-fact one can see who is a good physicist from one who is a novice, by seeing how this relation is used by him.

This was joked by Landau: I can measure the energy and then look at my watch, time is just a parameter. But Einstein and Niels Bohr argued “during a very short time interval one must be careful what energy is allowed and what is not, there is a constraint on the windows of errors or uncertainties”.

2. Life-times are arbitrary variables as are energies, their means are not necessarily linked inversely as in case of the uncertainty relation itself, the latter gives a relation between the error-window which are linked inversely.

So watch out how much inconsistent description is given in an average article eg in Wikipedia and even in our text-books. These are training the future physicists very wrongly. One needs experience of solving good problems, one is to work in experiments of highest standard and understand them.

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Further OPERA of a comprehensible universe.

Following are the serious physics based remarks, analysis or studies I have made so far on OPERA collaboration’s experimental result or ones that can be read in this context. This measurement has surpassed in my opinion all bounds of doubt and uncertainty. What remains is an anomaly, in this article I will give some suggestions on how anomalies if any can be addressed and make other pertinent remarks.

Before that here are the serious articles on OPERA so far — only 1 humor based article is on OPERA with popular musical analogies, I will mention it just for the heck of it and presume it does not take any one away from scientific context, but then serious and good quality experiments aren’t necessarily understood by serious physicists who keep on making vague comments which is more of a danger toward science than just humor:

[in order of chronology, into past]

Article 1: The time energy uncertainty relation. 

Article 2: Further OPERA of a comprehensible universe — the current blog you are reading.

Article 3: The sociology of skepticism. 

Article 4: Why scientists think photon is mass-less.

Article 5: What do we know about photon ? (Light).

Article 6: Why the neutrino and photon break-up?  — You may avoid this it’s just humor.

Article 7: Fundamental things you should know about the neutrinos. 

Article 8: Just a few implications of the OPERA neutrino result. 

Article 9: The OPERA neutrino results. 

Article 10: Is a photon always moving at the speed-of-light? (current title: What are photons) — This one is before I knew anything called OPERA experiment exists, although written less than two weeks ago.

Article 11: Why nothing moves faster than light? — on my main blog site, written April this year.

Now back to this article:

1. How to address the issue if this result is an anomaly — a correctly measured anomaly at that). Instead of depending on another experiment the OPERA can simply divide it’s ~16000 neutrinos into 16 groups of 1000 neutrinos each, — or is it 15000, does not matter as far as the idea goes.

If a systematic glitch is present it will only show up in 1 or more than 1 group. If you think it is present in all 16 groups you are saying it will be present in 16 million neutrinos as well, hence neutrinos bought a glitch from Walmart so that photons can not pace beyond the neutrino.

It’s like neutrinos taking drugs to pace beyond photons, but they are allowed to do that.  Why is photon such a lazy guy, he can buy his favorite bike, who stopped him before the Olympics? The conditions of the experiment are equally affecting both neutrino and photon baseline, a feature only good experimentalists understand why the systematic error issue of GPS clock etc is a meaningless diversion from the real issue.

2. The experimentalist in me says: the OPERA experimental measurement is correct. The systematic errors are in control, — finding more systematic error is your problem, the statistics is in control — finding more statistics is your problem, the mean value is sharp and completely out of the bound of the errors, — you can quote the mean as a precise result.

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Why scientists think photon is mass-less ?

There are a bunch of values from various experiments that can be said to be a measured value of the mass of the photon ..

A photon mass ranges from 10^{-7} eV – 10^{-27}. With such wide range of a mass we still have a firm founding on why photon can not be taken to be an extremely small mass rather it is taken to be a zero mass.

Even with the highest possible value measured it is by a factor 10^{-12} smaller than the mass of the electron — imagine a photon is associated with a hypothetical charge of the electron, for comparison sake of mass, we can give it the charge for free.

The photon is at-least by a factor 10^{-7} times smaller than the almost mass-less neutrino which is by a factor 10^{-5} smaller than the electron mass even if it were to have a charge of an electron, which it does not.

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