Physics
How do airplanes fly? The next time you find yourself in an airplane, look around at your fellow passengers. How many of them would be able to explain to you what force keeps the hundreds of tons of metal up in the air? How about yourself? Would you be able to explain this applied physics feat to the person sitting next to you?
Wings are simple and straightforward devices, yet misconceptions abound on how they work, and many people carry wrong perceptions on their lift-creating mechanism. The 'equal transit time' fallacy being the most prominent misconception in this area.
The…
Einstein’s Achievements ( Part : 1)
Einstein’s theory for Brownian motion: The motion of tiny particles suspended in liquid is caused by the kinetic energy of the liquid’s molecules.
In 1827 the Scottish botanist Robert Brown (1773–1858), while using a microscope, observed that pollen grains suspended in water were in constant motion, which he supposed was caused by some ‘‘life’’ in the pollen. He added minute particles of nonliving matter to water and observed the same motion. This phenomenon was not explained until the kinetic theory of molecular motion…
Through my colleague Marco Cirelli I got to know about the effort of 36 high-school student of Charlottesville (VA), who are fund-raising for a trip to CERN this spring. I thus visited their home page, and got favourably impressed with the organization of their campaign, which betrays their strong collective interest in the trip.
Beware, I am not old enough to have completely forgotten that, as much as I was interested in Science already as a teenager, back then that was not the main reason for being enthusiastic about school trips, even when we visited science museums or such. I am quite…
vongehr |
Precognition is under scientific investigation, though often with the aim to obtain null-results in order to discredit such ideas. In fact, “extra-sensory perception” (ESP) and “precognition”, “premonition”, “presentiment”, and so on are misleading terms, as was discussed in detail in “The Science of Precognition: Cosmic Habituation versus Decline Effect”. A better term is “paranormal”, which implies that the effect, if it exists, requires mechanisms outside of what is known. “Precognition” is at most “paranormal prediction”. If it exists at all, it will become normal after we figured out how…
Update: I have modified the title of this post [originally: "Opera's Statistical Booboo"] and the text below (in places I marked accordingly) upon realizing, thanks to a very good point raised by a reader in the comments thread below, that the idealization I was making of the measurement described below made my conclusions too hasty. Read the text to the end if you want more detail.
In data analysis, Gaussian distributions are ubiquitous. But that does not mean they are the only distribution one encounters ! In fact, it is unfortunately all too common to find unmotivated Gaussian assumptions…
The more I read on this topic, the less confident I get. If you wish to read a solid technical explanation, I recommend a reply by David Simmons-Duffin sent to me by Henry. It all comes down to Lorentz invariance and unitarity when considering propagators.
In technical tales, if so much as one step is not understood, the path gets lost. I'll point out a few places where I get confused. He writes down the potential between two stationary particles for an arbitrary spin-L force carrier in momentum space:
I better just quote the man's description of this beast:
where is the…
In this century, I believe that Physics will enter into an another remarkable area of basic understanding which we can not discover yet. No, I am not saying about the experimental facts of CERN or Fermilab. I am saying about a completely new aspect of Physics which may be related with some symmetry of nature. Really, symmetry is a very powerful tool for physicists of understand the complicated natural phenomena more simple way.
Now, what is symmetry? we are very much concern about symmetry but it is impossible to explain symmetry in…
Occupy Hilbert Space is a quirky event proposed by a Facebook friend of mine. A Hilbert space is a formal mathematical construct in which the information about a physical system is represented by vectors. In physics we most often encounter the concept of Hilbert spaces in Quantum Mechanics. They are not limited just to quantum mechanics. For my submission I will show that we are all occupying a Hilbert space right now.
Niel Bates describes it like so.
There's always room for one more and when the police show up they'll never be able to find us…
A blog is by nature a place where things move on fast. Articles disappear beyond the horizon in the matter of a week or two, and only rarely get resuscitated by a later article linking them back from oblivion.
At Science 2.0 things are no better than in any other blog sites, with the aggravating feature that there is no "archive" button, nor a "random post" feature. Since I believe that many of my articles are not very connected to the specific time at which they have been written, I have in mind to reorganize the material somehow, when I have the time. However, this looks like a grievious…
Was Galileo wrong?
The answer is no. Then what is special in Einstein's Special Theory of Relativity(STR)? The answer is that in STR , we know about the kinematics of high speed objects. In a certain limit the Lorentz Transformation or Einstein's Relativity merge with Galilean Transformation. The limit is " Object is moving very slowly, to be most precise the object is moving slowly with respect to speed of light".
In STR the master assumption is " In every inertial frame of reference the speed of light in vacuum is constant( which is known as c )." From this assumption there is a strong…