“There are 10^11 stars in the galaxy. That used to be a huge number. But it's only a hundred billion. It's less than the national deficit! We used to call them astronomical numbers. Now we should call them economical numbers.”
Richard Feynman, who would turn 97 years old today. Happy birthday, mr. Feynman!
All light is made of electromagnetic waves. This means that like any wave, there is
something repeatedly sloshing back and forth with light. A water wave is crests and troughs on the
water going up and down over and over as they travel across the surface. Light waves have some resemblance in that
with light, it is electric and magnetic fields which are periodically wobbling
back and forth.
When a mirror reflects light, it experiences a slight push but it is negligible in our everyday lives. Our furniture is not moving because due to radiation pressure of light, a 100 Watt light-bulb causes a radiation pressure that is only a trillionth (one part to 1000000000000) of the normal atmospheric pressure.
As yesterday in Italy was the equivalent of Labor Day, and today is a Saturday, with people around me exploiting the three-day rest for a recreational trip, I do not feel in a very productive mood, so rather than writing something original here I will exploit other people's work, pointing at what I found interesting or anyway worth my attention among the papers appeared on the Cornell Arxiv in the last few days, and other assorted material.
Detecting ionizing radiation does not mean that a disaster
has or will occur. Detecting radiation
is generally a good thing if the radiation is expected, intended or
natural. We and all living things on earth
are naturally radioactive. This is due
primarily to our requirement to have a healthy level of potassium and carbon in
our bodies (and these are both naturally radioactive).
"B.W. Lee also carries much of the responsibility for calling the Higgs boson the Higgs boson, mentioning repeatedly 'Higgs scalar fields' in a review talk at the International Conference on High-Energy Physics in 1972."J. Ellis, M.K. Gaillard, D. Nanopoulos, "An updated historical profile of the Higgs boson"
First collisions of protons at CERN's Large Hadron Collider are expected to start the first or second week of June. The LHC was restarted in early April after a two-year pause to upgrade the machine to operate at higher energies for a second three-year run . At higher energy, physicists may see new discoveries about the laws that govern the universe and SUSY diehards - physicists who support the hypothesis of space and time called SuperSymmetry - maintain hope new discoveries bolster them and change the current accepted theory of physical reality, the Standard Model.
When a feather or a plastic bag or almost anything light is
placed in water, these items will generally float. This is easy to understand if you think of
water being more dense than the other item.
If you put something heavier in water, it tends to sink like a rock or a
piece of metal but this doesn't fully explain how an iron ship can float.
I received from Ravi Kuchimanchi, the author of a paper to be published in Phys. Rev. D, the following summary, and am happy to share it here. The paper is available in the arxiv
Are laws of nature left-right symmetric?