how time slows down because we are fast wrt it. Reply


So here is the article “Stephen Hawking Einstein and my ideas” written the 4th of December 2010.

Thinking about time and relativity it just passes my own thinking that Hawking has merely made accessible most of the elegant yet incomprehensible genius of Einstein. But thinking more about this it also occurs to me that Einstein was not thinking in terms in which S. Hawking or anybody explaining his theories was.

Nevertheless Hawkings work is in itself the work of a genius because explaining these not so simple (after all) work of Einstein can only be achieved by a genius of Hawkings caliber. Hawkings clarity, wit and unimaginable access to all the physical ideas of our Universe and comprehensibility is a trademark, a sign of uniqueness. More…

“Peter Irks Rhea and Commits Felony” is an easy way to remember the Spectrochemical series. Reply

1. Peter Irks Rhea. Commits Critical Felony. Felony committed at Night is Minimum.

2. Cold Condition. (say) NO 2 Night Halting (for 3 Hrs). Non-Committed-Souls Head 2 Office. Office Hours For Super-Committed-Nerds Closes Before.

In a crystal field the d-orbitals of the metal ions gain degeneracy due to Ligand electrons. (That is the equal energy levels of d-orbitals of metal are now unequal due to electron repulsion from Ligand, depending on in which direction the d-orbitals are pointed to Ligand)

Which ions (or Ligands) are more powerfully degenerated (or degenerative) and which are less? There is an order called Spectro-Chemical series.

So I just thought a little to easily remember the series.

1. When geometry (eg tetrahedral or octahedral) and Ligands are fixed how does it affect the metal ions? More splitting denoted by >.

(strong field) Pt4+ > Ir3+ > Rh3+ > Co3+ > Cr3+ > Fe3+ > Fe2+ > Co2+ > Ni2+ > Mn2+ (weak field)

2. When geometry and metal ions are fixed how are Ligands affecting?

CO (~) CN- > NO2- > NH3 > NCS- > H2O > OH- > F- > SCN- (~) Cl- > Br-


The concept behind Crystal Field Theory (Incidentally developed by Physicists like Hans Bethe as an alternative to Valence Bond theory) is described in detail here.

How much meat Samuel eats? Reply

Its a straightforward question, right? True. We need to keep a tab on Samuel’s dietary intake, count the calories, as simple as that.

What if Samuel lived in 5000 BC, I am not kidding, except perhaps we need to be sure on the name. Its no more a straightforward question nevertheless answerable.

It uses a few steps, which are nonetheless viable given our tremendous and amazing scientific strides. Go home, and make a list, we will perform this task of finding the dietary habits of primitive men and women.

Collect bone samples of primitive inhabitants.
Arrange a mass-spectrometer
Be ready to be amazed, the spectrometer allows to distinguish between elemental mass of samples based on the property of magnetic objects.
Science fact 1; The bone contains two types of nitrogen called isotopes of nitrogen based on their elemental mass composition. One is Nitrogen-15 slightly heavier than the Nitrogen-14. A specified number of Nitrogen-14 would differ by only 1 gm for every 14 gm, if we replace them by same number of nitrogen-15. By eating meat one goes on accumulating the heavier Nitrogen More…

A Photon has no mass. It can’t rest. Reply

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.



When I made a presentation on why we shouldn’t call photons mass a “zero rest mass” I was thinking we make such mistakes only informally until just couple minutes ago the above texts flashed across my rest seeking eyes. (– or check this one, there are also some other articles that talk about this idea, after I realized my mistake years ago, but perhaps they are in terse form, and will be revised upon availability of time and a priority)

This is at-least the 4th mistake I have spotted in text books in recent years. Other mistakes I realized as my own mistakes or of others in discussions.

I have made this terrible mistake of calling photon mass as a rest mass just like the authors of this text book. Photon just doesn’t have mass.

(Its fine to say photon has zero mass, but not fine to say photon has zero rest mass, just don’t use the rest term, it causes photon to smirk at ya and say look you don’t understand me, okay, so just bugger off)

Because it doesn’t have mass (from which it does follow, it has zero mass) photon flies off always at same speed, hence no rest frames. v=0 is not possible for waves called light. v=0 is possible for particles with mass. A mass-less particle is an extended region as its a wave and one cant wish a velocity for it as one can for particles with mass. Zero velocity for such extended regions with other conditions is out of consistency.

One should also remember E=mc-square is not valid for photons. Its valid for particles with mass only hence for processes involving photons and other particles but thats because particles other then photons have mass (and energy) but photons have energy as well (but no mass) and this energy is consumed or released by other particles (such as pions or electrons). All in all due to energy conservation E=mc-square is valid, but not for photons alone.

This book is one of my most favorite book at junior coll level, a brilliant piece otherwise. Written by highly qualified professors from Ivy leagues and the likes, but such errors have persisted from ages. This book was ” originally ” written in 1970s — A decade before I saw light of the day for the first time_ first used by me, 20 years ago, I was 17, when I was yet to be qualified to comment on Relativity.

Its a widely used textbook and admittedly one of the best and most brilliant textbook at this level. University Physics originally by Young et al.

Interesting Physics facts one would love for ever Reply

Interesting fact 2; Give an example of a motion where when we apply a force on the object, the force produces motion of the particles along its own direction, the speed remains finite but does not change. According to F = ma, Newtons laws are valid for the motion but speed remains constant, while F is there, v does not change.

Since a = 0, with nonzero F and constant v, one could see this as a diversion from particle mechanics as formulated by Newton, towards a higher understanding, one could argue this as a great inflection towards Quantum Mechanics.

Also note that we are not talking about circular uniform motion where F does not change v, but there is non zero a. F is transverse to particles motion.

Interesting fact 1, certain forces do not obey any of Newton’s laws, in either its strong form or week form. Magnetic forces unless generalized suitably do not obey any form of the Newton’s law, strong = strict, week = partly strict.

Some discussions on fact 2

Would a quantum of charge in a potential changing energy levels occur without acceleration? I’m not sure if elementary particles change velocity instantaneously or do they accelerate.


Elementary particles change velocity if they have mass. — If they have mass, they have rest mass.

Photons on the other hand don’t have the property called mass. — So its erroneous to say Photons don’t have rest mass, they just don’t have mass, saying they don’t have rest mass would mean; they have zero velocity in some frames, which is physics wise unacceptable.

So elementary particles except zero-mass particles such as photons, change their speeds under acceleration. “Potential changing energy levels” simply means there is a force and acceleration, hence change in energy, speed, momenta etc of the elementary particle such as electrons in orbits.

— Their quantum numbers are different for different orbits, hence, energy and velocity etc are different. In the orbits the electrons would fall down to a smaller radius if they were to lose energy.

Since they are wave-particles we are talking about average values of radius, which decreases accompanied by some acceleration. So the answer to your query is YES, there is acceleration of these particles, in orbit changing processes. (excitation or de-excitation)

The above point of mass-less particles and particles with mass is what classically separates them as waves and particles. — mass-less = wave and particle otherwise. And speed is a variable if particle mass is non zero and mass keeps on changing as well. But zero mass would mean mass and speed are constants.


So in short waves; speed and mass are constants. mass is zero. speed is constant and finite.

Particles; mass and speed vary from zero towards a finite value as decided by the wave (above).

These are elementary particles and waves which come under two categories; matter waves (such as electrons) and non-mechanical (or em) waves such as (photons).

But the hints to my question lies on considering yet another category of waves viz; mechanical waves.

Happy Diwali ! Reply

A very happy Diwali to all my readers and all those who I can’t directly wish so considering the vast gap that technology can still not measure up in connecting us all physically.

Diwali or Dipaballi as well know is an Indian celebration in the month of November although the dates might alter to nearing the months of October or December considering the fact that Indian vernacular calendar is measured wrt the motion of moon and not the modern solar calendar which is most precise for mos of civilian time measurements on our planets. That simply means celebrations such as this might alter to weeks if not months altogether. I don’t have a data centric information regarding how much Diwali alters though, in terms of a Julian Calendar.

Thankfully much of our important transactions are based on the sun based calculations which means, in modern times, a great deal of corrections coming from the sidereal constants of motion. A sidereal constant of motion refers to having to fix all references wrt to distant stars so that fluctuations coming from sun or Intra-solar objects such as planetary perturbations itself can be properly accounted for.

Now coming back onto the idea of Diwali I am not going to delve into how much we want to signify it as a victory of morality over evil, and how much myth is important in our philosophical and existential moorings, such as how a monster by the name of Holika — gender specifically the feminine form of evil was killed by Sri Krushna.

I never like to take exceptions to how much vilification outdated traditions of our heritage and culture entails, and robustly establishes into a modern and civic society, which aims to be progressive and free from malice at the same time. The reason is I never see much intellectual debates that are free from wishful thinking and hypocrisy on one extreme and blindfolded adherence and a ready to die or kill attitude of the right wing inclinations in support of the veracity and usefulness of such traditional ‘wisdom’ and folklore. More…