Physics
In quantum physics, objects can be in more than one place at a time and future events can change the past - don't get caught up too much in that or you won't sleep at night.
A new paper says quantum physics can be even spookier. Using the “chained” quantum Zeno effect, the researchers write that they have discovered a form of "almost psychic communication" in which information can be exchanged between two parties without photons, or any physical particles, traveling between them.
Let's invoke "Alice" and "Bob", the most famous couple in physics, to illustrate what they mean. The basic set-up…
I have decided to rescind this proposal. Stars in a galaxy travel at one velocity, light at the speed c. There is only one velocity involved in applying the product rule to the definition of a force as a change in momentum. Note that is not a trivial application of the product rule either. Newton's second law is invariant under Galilean transformation. The dm/dt dR/dt is not invariant.
Here are my big picture house rules: no equations in LaTeX or Mathematica. Graphics are allowed so long as they are done by hand. Visually, images break up the…
Hank |
Cryogenic Dark Matter Search (CDMS) collaborators are reporting what could be a weakly interacting massive particle (WIMP) signal at the 3-sigma level. In common parlance, that is 99.7 confidence - which sounds high. But to physicists it really means they have 3 bumps in their data that could be a WIMP, which means it might be a hint of dark matter.
That sounds like a lot of qualifiers but particle physics is conservative that way. Data means what it means and not much more. But certainly not less, and that is pretty important too.
5-sigma is a modern designation for 'discovery'…
Pictures showing the structure of matter and the organization of subatomic particles in different categories abound. Indeed, cataloging and classifying entities subject of study is a powerful means of grasping their essence and infer their properties. The most striking example I can offer is the Mendeleev table of elements (which allowed its creator to spectacularly deduce the existence of elements not yet discovered); but there are many others, like the Hertzsprung-Russell diagram of star classification, or the one for galaxies, or the cataloging of animal species...
So I am all for nice,…
Probably no signs of gravitational waves, signs of dark matter but not a discovery. That is the word from this first day of the American Physical Society's meeting in Denver Colorado.
In the plenary keynote session of the meeting today, I asked a question of Lloyd Knox of the PLANCK collaboration. My question regarded the B mode polarization data and what it may show. He said that this data would be officially released next year. He also expressed the professional opinion that the data may not show a strong gravitational wave signal. This would be significant since the simplest…
Results from Planck and AMS-02, but also the way they are often presented, have created a very exciting situation. Its exceptional character has led me to quickly write an article, Planck data, spinorial space-time and asymptotic Universe, and to make it public for open discussion.
Are dark matter and dark energy really at the origin of the present value of the cosmic velocity/distance ratio ? Is dark energy really necessary ? Unfortunately, present analyses are based on the ΛCDM
model right from the beginning.
I present here an alternative approach. My suggestion is based on a pre-…
"What are the radiation doses to airplane passengers from the intense bursts of gamma-rays that originate from thunderclouds?" researchers asked at a press conference during the European Geosciences Union in Vienna today.
Scientists have known for almost a decade that thunderstorms are capable of generating brief but powerful bursts of gamma-rays called terrestrial gamma-ray flashes, or TGFs. These flashes of gamma-rays are so bright they can blind instruments many hundreds of kilometers away in outer space.
Because they can originate near the same altitudes at which commercial aircraft…
There have been other attempts in the past, so this is not strictly a new idea. However I found the interactive web page at http://htwins.net/scale2/ extremely well constructed.
It is a graphical display of the largest and smallest structures from galaxy superclusters down to quarks and the Planck length. By moving a scroll bar left or right, you can get a very clear sense of scale of the different things. And in so doing you learn the relative size of different objects, from planets to stars, or from stars to galaxies; or vice-versa, from cells to molecules and atoms.
I highly recommend it!
Now that the Higgs has been found, the current hype in popular science magazines suggests that the most pressing question in fundamental physics research is whether new particles will be found at the Large Hadron Collider: Is Supersymmetry the right extension of the standard model? Or are there new extra dimensions of space-time ? Can microscopic black holes be created in particle collisions ? I think all of you have heard some of these questions enough times by now.
However, I beg to differ. All these questions are driven by something we do not understand at the theoretical level -the…
The T2K Collaboration released today an analysis of their data in the Cornell Arxiv. T2K searches for electron neutrinos appearing in a muon neutrino beam produced by the J-PARC accelerator facility in Tokai-Mura, using a near detector located 280 meters downstream of the proton target, and a far detector (SuperKamiokande) at 295 km from the source.
The appearance of electron neutrinos in a muon neutrino beam is a very important oscillation signal of neutrinos, that allows the measurement of the parameter theta_13, one of the so far less-well known parameter of the neutrino mixing matrix.…