Someone on this site recently posed the following thought experiment questioning the postulate of special relativity that no object can travel faster than the speed of light - c. Imagine a one dimensional problem in which two travelers, move close to the speed of light, but in opposite directions - one moving close the speed of light in the positive direction and the other traveler moving close to the speed of light in the negative direction.
Wouldn't these observers perceive the relative velocity of the respective other as exceeding the speed of light (i.e., approx. 2c)?
Special relativity posits the following:
There is often an uncomfortable and artificial hierarchy amongst theorists and experimentalists. Those exalting pure theory often forget that applied science is an art unto itself as is engineering. There are many problems in applied science or engineering in which theorists are ill-equipped. Of course, there are rare examples of great theorists who were also great experimentalists such as Fermi. Steven Quake
describes some examples of the crossover between pure and applied science and the scientists behind these initiatives.
The Higgs field isn't the only thing the LHC might unearth. A while back Sean Carroll posted a great discussion
of other possibilities including supersymmetry, dark matter and something not yet predicted.
In all the hype surrounding the Large Hadron Collider during the last few years, it was easy to miss the fact that low energy physics was still accomplishing a lot - and that no one was sure what the LHC could really do because we didn't know what needed discovering.
What we think it will do is based on the success of the indirect approach in science. Darwin's evolution by natural selection, for example, gained early acceptance because without it nothing much in biology made sense. Later discoveries including genetics and a detailed fossil record reaffirmed that what makes the most sense can often be true.
A well known professor of analog circuit design and theory once said "all models are wrong". Analog design is particularly rewarding and challenging, I believe, for this very reason. Those words have echoed in my mind during many junctures in my journeys to learn something about the physical world. Whether you are a theorist, phenomenologist, experimentalist or some combination of these, this fact is inescapable.
I am fascinated by how concepts of everyday life leak into all scientific thought, whether it be an elementary concept in engineering or within the confines of some rarefied physical theory. And this is a topic I hope to write much about.
I have been working in research for 36 years now. As the millennium turned, and our department found itself being starved of staff like the Hodja’s Donkey
, I found myself being called upon to assume some small teaching roles. I found two incompatible things: one, that I really enjoy teaching, even more than research; two, that there is so much physics that I never had learned properly.
The December '08 issue of symmetry magazine (http://www.symmetrymagazine.org/pdfs/200812/dec_2008.pdf
) presents an interesting article about the benefits of particle physics research to society from an economic, social and education perspective.
The ripple effect of basic research in physics such as elementary particles has driven development of technologies as far ranging as grid computing, superconductivity, cancer therapies and of course the World-Wide-Web. Many of these breakthroughs might never have arisen under an incremental approach motivated purely by a corporate bottom line.
How many Cardinals can fit on the head of a pin? Still unknown, but Stanford physicists can at least tell us how many letters formed by quantum electron waves can fit on the surface of a sliver of copper - two; as in "S" and "U." That's for 'Stanford' and 'University' if you haven't caught on and Cardinals are their ... oh, never mind, if you didn't already get it you stopped reading by now.
So how small is that? The letters in the words are assembled from subatomic sized bits as small as 0.3 nanometers, or roughly one third of a billionth of a meter. Bonus: the wave patterns even project a tiny hologram of the data, which can be viewed with a powerful microscope.
A team of Yale University astronomers say that galaxies stop forming stars long before their central supermassive black holes reach their most powerful stage, meaning the black holes can’t be responsible for shutting down star formation.
Astronomers believe that active galactic nuclei (AGN), the supermassive, extremely energetic black holes at the centers of many young galaxies, were responsible for shutting down star formation in their host galaxies once they grew large enough. It was thought that AGN feed on the surrounding galactic material, producing enormous amounts of energy (expelled in the form of light) and heat the surrounding material so that it can no longer cool and condense into stars.
Scientists have finally solved one of the major mysteries of star formation - how very massive stars form without blowing themselves apart in the process. According to star formation theory and previous simulations, the internal pressure created as a very massive star begins to shine should counteract the gravitational force pulling more material in, blowing away the outer layers of the star before it can get sufficiently massive.
Observations, however, show that stars exist with masses above the theoretical threshold and often coexist with other massive stars in binary systems - providing a mystery to astrophysicists until now.