Category Archives: Physics

Thursday Moment of Zen

I Can Has Gravity?

cat,Gravity,caption

By two_kittehs

Gravity Kitteh made it to the first page of ICHC/lolcats this morning just like Soviet kitteh did  a couple of weeks ago. Don’t know why but Soviet kittehs has a funny. I especially love the pissed off expression of the feline! Other FP lols here

Canary Got the Cat

By two_kittehs

Gravitational Waves Detected

By two_kittehs

Exactly 100 years after the publication of the general theory of relativity, scientists find proof of gravitational waves predicted by Einstein.

Five Questions

Questions that have been on my mind in no particular order.

  • What can Trump do to lose his first place position in the polls for Republican Presidential hopefuls?
  • Are “anti-establishment voters” of this election cycle,  the new tea-partiers?
  • Einstein’s theory of General Relativity celebrates a century and gets all the press while Maxwell’s seminal theory of electromagnetism celebrates 150 years, and barely gets a mention, why no love for Maxwell?
  • WTF does curating a wardrobe (a term favored by fashion and style bloggers) mean? You have clothes, you wear them. Unless you work in a museum you are not curating anything.
  • Best score of the year, Bajirao Mastani or Katyar Kaljat Ghusli?

 

By two_kittehs

Do you have any burning questions of your own? Answers to my questions? I would like to hear them, Kthnx bai.

100 Years of the General Theory of Relativity

By two_kittehs

Einstein’s greatest achievement and one of the foremost intellectual achievements of all time completes a 100 years this year. If you think that you have no use for Einstein’s seminal theory, think again. The accuracy of the  ubiquitous navigations systems that depend on the Global Positioning System rely on special and general relativistic corrections to Newton’s Laws.

Other physics related posts here.

The Story Behind Schroedinger’s Cat

Box Kitteh is Not Happy With Your Offering

By two_kittehs

Update: I just realized that I have already posted this lol before. To make up for that lapse, I give you another box kitteh!

 

Cosmos Episode 6 : What lies Within

Breaking up a system into its tiniest building blocks, is an approach that provides a great insight into whatever you are studying, from the hydrogen atom to the Universe. To figure out the evolution of massive stellar objects one needs to understand its tiniest components, i.e., matter at the atomic and subatomic levels. Episode 6, focused on this idea in general and the elusive neutrino in particular.

In episode 6,  Neil De Grasse Tyson started with the universe contained in a dew drop, he bored deeper and deeper till he reached the  atomic level.  Atoms, are mostly empty space with a dense positively charged nucleus.  The electrons that surround the nucleus are tiny in comparison.  We also learned about forces of electrostatic repulsion and then the nuclear forces which bind the atom together. Nuclear attractive forces have to be much stronger than the repulsive electrostatic forces to keep the positively charged nucleus together. The nucleus also consists of particles with charge zero, the neutrons  which are necessary to keep the like charged protons together in the nucleus.

Now that we know what we are made of,  we also need to know the means through which particles interact with each other.  Most of the macroscopic interactions on our planet are a product of the electromagnetic force which is one of the four fundamental forces of nature, and the one we understand the best

The other fundamental forces are the gravitational force, and the two nuclear forces; the strong force and the weak force.  It’s the weak force that gives rise to aforementioned neutrino.  A mass less and charge less particle that was predicted by Wolfgang Pauli based on energy conservation arguments.  The argument boils down to this: the total mass and energy of any given system is always conserved, no exceptions.

Neutrino, or the little neutral one in Italian is an elusive particle and extremely hard to detect because it does not interact much with anything at all, since it has almost zero rest mass and no charge.  It is a product of nuclear beta decay, a type of radioactive decay*. This makes the neutrino a great candidate to study about the origins of the universe and stellar cores.  De Grasse Tyson took us to the neutrino detection laboratory in Japan.  The secrets of  neutrino astronomy are yet  to be revealed. See Explanation.  Clicking on the picture will download<br /><br /><br /><br /><br /><br /><br />
 the highest resolution version available.
Credit: Super-Kamiokande Collaboration, Japan
Earlier entries about Cosmos are here.
*

Natural radioactive decay

The number of  electrons in a neutral atom determines its chemical properties.  The elements are arranged in the periodic table in the ascending order of the number of electrons, their atomic number.  As the atomic number increases we need more neutrons than protons to keep the atomic nucleus together. This works up to a point, addition of neutrons makes the nucleus unstable and we get the phenomena of natural radioactivity.  For example,  Uranium which is naturally radioactive and has no stable isotopes.  Uranium 235, its most abundant naturally occurring isotope has  92 protons and 143 neutrons.

More About Light in Cosmos

A brief recap of the properties of light that we have encountered so far in Cosmos.

  • The speed of light through vacuum is nature’s speed limit.
  • Light travels in straight lines.
  • The speed of light depends on the medium.
  • Visible light is composed of seven primary colors.
  • Energy of light waves depends on their wavelength.
  • Our eyes are sensitive to a small band of electromagnetic radiation.

These properties were hiding in plain sight but it took centuries and the work of many individuals to unravel these properties.  Lots of imagination and hard work went into getting nature to reveal its code to us.  You may ask, how does this concern me?  Why should I care?  It does because the entire edifice of modern life, from your hand held device to your camera phone uses this knowledge.  To paraphrase Newton, each of us can see farther because we are standing on the shoulders of giant. Technological progress is possible because of research in the pure sciences. Unfortunately funding for science is getting shortchanged these days in the name of fiscal prudence, see for example, sequestration.

Still to come:

  • Light can demonstrate both wave-like and particle like phenomena.
  • Light waves are transverse electromagnetic waves.
  • Light can travel through vacuum

The last property has been taken for granted but never been elaborated upon by Neil De Grasse Tyson while narrating Cosmos.  There is a great story lurking behind that fact, I hope he tells it in one the upcoming episodes.

 

My reviews of previous episodes here , here and here.

Let There Be Light, Review, Cosmos Episode 5

At start, no has lyte. An Ceiling Cat sayz, i can haz lite? An lite wuz                       —Lolcat Bible

 

The-Electromagnetic-Spectrum

Note :1nm = 10-9m

It is as if Neil De Grasse Tyson read my last review, and decided to give us the physics behind the light show of last week.  He covered a lot of ground, this week.    This episode began its exploration of light with geometric optics and pinhole cameras and ended with speculation about dark matter.  This week’s  history lesson told us about  the contributions of the ancient Chinese experimentalist and philosopher, Mozi,   and the Arab philosopher-scientist Alhazen, of the ancient Indian mathematical concept of zero.  An excellent counterpoint to those who insist that Christianity  was  an essential  aspect of the scientific revolution.  Unfortunately  Mozi’s teachings did not survive the Chinese thought police.  Like the Inquisition era Catholic Church they too were afraid of the open exchange of ideas.  No one has a monopoly on either the smart or the stupid but the cultures that allow an open exchange of ideas flourish, while those who stifle them, don’t in the long run.

Continuing our exploration of light, Tyson revisited  Isaac Newton and  his discovery of the spectrum of visible light.  Newton figured out that sunlight or white light is a composite of  the seven primary colors, VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange and Red).   Newton was not the main star of Sunday’s Cosmos, instead it was Joseph Fraunhofer, for his contributions to spectroscopy.  He was the first to observe the solar spectrum with a telescope and analyze it.   De Grasse Tyson then described the atomic structure of  hydrogen, and quantum mechanical explanation of its spectrum. He then generalized it to atoms of elements more complicated than hydrogen.  Thus looking at the spectrum of a heavenly body we can  figure out what it is made of.

In a brilliant graphic Tyson demonstrated how the New York skyline changed when we focused on the different parts of the electromagnetic spectrum.   The different parts coinciding with different wavelengths. To explain the concept of a wavelength, Tyson compared light waves and sound waves.   Missing however was any mention of Thomas Young, who experimentally proved the existence of the wave nature of light.  Also, there was no mention of Newton’s corpuscular theory of light which had to be eventually discarded since it could not explain interference and diffraction.

What I love about physics in particular and science in general, that it does not matter whether you are Newton or Einstein, if what you say does not agree with experiment your theories have to go.  Put up or shut up.  Physics does not bow to the rules of the thought police.

Tyson still has to discuss the wave-particle duality. Though, he briefly touched on quantum mechanics while discussing the hydrogen atom he has yet to talk about the Uncertainty Principle.  I am sure that the quantum revolution of  the early part of the last century  will be the subject of a future episode.    The changes it  brought about,  in how we perceive both matter and light were radical.  As is always the case, that revolution too had its own thought police.

Previous reviews of Cosmos,  here and here.

Pundits React to the Cosmos Reboot

Greg Pollowitz at the National Review thinks Cosmos is boring;

I think we have a real dud of a show in the making.

I beg to differ, my reviews of Cosmos are here and here.

Daily Beast’s  David Sessions, argues that Bruno was a theologian not a scientist.

What Cosmos doesn’t mention is that Bruno’s conflict with the Catholic Church was theological, not scientific, even if it did involve his wild—and occasionally correct—guesses about the universe.

Sessions must have fallen  asleep while watching the episode, because I distinctly remember De Grasse Tyson mentioning that Bruno’s was not a scientist.

Andrew Sullivan at the Dish, finds the history lessons cartoonish.

The segment previewed above is on the 16th century priest and philosopher Giordano Bruno, which includes deGrasse Tyson intoning that the Roman Catholic Church sought to “investigate and torment anyone who voiced views that differed from theirs”. Really?

Yes, really. Has the great scholar of history not heard of Galileo? Besides, what does it matter if Bruno was not a scientist? I thought Andrew Sullivan was against torture. Or is torture okay if condoned by the Catholic Church?

Besides have Sessions and Sullivan not heard of Copernicus? He delayed the publication of his book until the year of his death.  The book, postulated a heliocentric solar system based on his observations of the planets.  Perhaps, because as a man of the cloth, Copernicus was aware of the blow back from the Church if he published his thesis.

What exactly is Bruno’s being a priest supposed to prove? In fifteenth and the sixteenth  centuries, not many besides priests and noble men had the time to dedicate their life to philosophical or scientific questions.  I don’t really get Sullivan’s and Sessions’ criticism.

Cosmos Episode 4: The Journey Across Space-Time Continues

Neil De Grasse Tyson and Cosmos continue its journey through space-time.  The reason this journey seems stranger than science fiction is because it  is beyond our direct sensory perceptions.  In the interior of stars, the effects of both quantum mechanics and relativity cannot be ignored.   We can safely ignore quantum mechanical effects in our day to day lives,  unless we are dealing with matter on the atomic atomic scale or smaller.  As for relativistic effects, they become important  only when we approach the speed of light.   If you are interested in exploring what quantum mechanical  and relativistic phenomena would look like if we could experience them via our senses you should read the Russian born physicist, George Gamow’s Mr. Tompkins series.

Coming back to Cosmos, this week’s protagonist was the British astronomer William Herschel, voiced by none other than Captain Picard (Patrick Stewart to  non-Trekkies).  Herschel is credited with discovering Uranus among other things. The  exploration of space-time  dealt with the consequences of applying Newton’s laws of motion and that of universal gravitation to the astronomical objects.  Tyson also tackled the concepts of action-at-a-distance through the presence of  a  force field.  We  learned about an astronomical unit of distance, a light year, and the mind bending consequences of nature’s speed limit, the speed of light.

We were also introduced to  Maxwell’s equations and the origin of electromagnetic waves of which the visible light is but a very small portion.  If human beings are the products of intelligent design then pray tell why our eyes are sensitive to only a tiny fraction of the  electromagnetic spectrum?

I wish the show had spent some more time on the idea of ether, the Michelson-Morley experiment which failed to detect its existence and proved that light unlike sound did not need a medium to propagate. De Grasse Tyson introduced the work of Albert Einstein and talked about both the General and the Special Theories of Relativity.  The show ended with a thought experiment exploring what might be inside  of a black hole. A collapsed star with a gravitational pull so great that even light cannot escape it.  I do wish though that Tyson would spend more time discussing  the physics behind the dazzling  light show.

Although, none of the physics De Grasse Tyson discusses is cutting edge, most of what he tackles would be covered in undergraduate physics, it is timely and necessary.  Especially if it helps bridge the gulf that separates lay people from practitioners. The depth of scientific ignorance, seen in debates over climate change and evolution,  even by media heavy weights is mind boggling, so the timing could not have been better.

Lasting economic success is built on technological progress which is not possible without basic science.  This fact  seems to be lost on  policy makers, who give preference to tax cuts for the 1% over funding for basic science.   Industry is not going to step in to fund basic research, or any product that can’t be marketed for an immediate return.   We need science for the sake of science, to satisfy our innate curiosity, a purpose higher than increasing quarterly earnings.

You will find the review of the earlier episodes of Cosmos, here.