Posted on 01/25/2013 11:04:41 PM PST by neverdem
Only in physics can a few quintillionths of a meter be cause for uneasy excitement. A new measurement finds that the proton is about 4 percent smaller than previous experiments suggest. The study, published in the Jan. 25 issue of Science, has physicists cautiously optimistic that the discrepancy between experiments will lead to the discovery of new particles or forces.
“Poking at small effects you can’t explain can be a way of unraveling a much bigger piece of physics,” says Carl Carlson, a theoretical physicist at the College of William and Mary in Williamsburg, Va., who was not involved in the study. “And this case is particularly intriguing.”
For years, physicists have used two indirect methods to determine the size of the proton. (Unfortunately, there is no such thing as a subatomic ruler.) They can fire an electron beam at protons and measure how far the flying particles get deflected. Alternatively, physicists can study the behavior of electrons in hydrogen atoms. They shoot a laser at an atom so that the one electron jumps to a higher, unstable energy level; when the electron returns to a low-energy state, it releases X-rays whose frequency depends on the size of the proton. Both methods suggest the proton has a radius of about 0.88 femtometers, or 0.88 quadrillionths of a meter.
That measurement was not in doubt until 2010, when physicist Aldo Antognini at ETH Zurich and his team developed a new technique to probe proton size. They also used hydrogen atoms, but replaced the electrons with muons — particles similar to electrons but more than 200 times as massive. Muons’ additional heft enhances their interaction with protons and makes their behavior more dependent on proton size. After measuring the X-rays emitted by muons shifting between energy states, Antognini’s team published a paper...
(Excerpt) Read more at sciencenews.org ...
What's next? Planck's constant?
It so a cook can't keep up with physics anymore.
/johnny
Odd how this ‘measurement’ of the proton is very similar to our claims of the size, orbit, and viability of planets around other stars.
We can’t see the planets.
We only have light detectors that give us a reading of very minute dimming in the light, which we assume to be a planet.
Based on the length and extent of the dimming, we claim to know the planet’s size and orbit.
Amazing how continuously wrong we are about things we search for the truth.
Amazing how continuously wrong we are about things AS we search for the truth.
(that’s a sign I should go to bed. Goodnight all)
So ..... How long before they realize that it isn’t really there at all?
GPS is based on an earth centered concept... Not true, but it does get us within a few meters of where we want to go.
/johnny
They will just come out with a Planck’s Constant Compensator to account for the difference.
It's a working theory. That's all we have. I gripe, but that's a good-natured swirly.
We see through a glass, darkly. I seem to recall someone saying that...
/johnny
Researchers show how cells' DNA repair machinery can destroy viruses
Immune system molecule with hidden talents
With Shakespeare's help, researchers show potential of DNA for storing digital information
FReepmail me if you want on or off my health and science ping list.
Researchers show how cells' DNA repair machinery can destroy viruses
Immune system molecule with hidden talents
With Shakespeare's help, researchers show potential of DNA for storing digital information
FReepmail me if you want on or off my health and science ping list.
First: The Standard Model doesn't describe gravity, period.
Second: Physicists aren't desperate to "discover new physics." We're desperate to wring information out of experimental physics in new ways because the approach of reaching ever higher energies in our accelerators is simply not viable. We can't even get within orders of magnitude needed to investigate most speculative theories in high energy physics, and there is no prospect for doing so in sight.
We need new experimental results and we just aren't getting any. Hence micro-measurements of the difference between c and the speed of neutrinos in vacuum or anomalous results like this start to look intriguing. They seldom turn out to be anything but experimental artifacts.
And no, we aren't changing Planck's constant. In fact, in the new SI proposal, Planck's constant, the electric charge, Boltzmann's constant, and Avogadro's number are going to be set as defined constants; they will never change. What will happen instead is that the basic practical units (second, meter, kilogram, ampere, kelvin, mole, and candela) will change and we will be looking for ever sharper definitions of the practical units in terms of the atomic ones, instead of the other way around as we did in the past.
High energy physicists and cosmologists have been doing that for a long time already. In their unit system ħ = (h/2π) = c = 1.
Question for Physics majors....
Is Particle Physics built on the idea that EVERY similar particle in the universe has EXACTLY the same weight, dimension, and charge as every other similar particle?
Or, is there some level of acceptable deviation?
Only the Japs could possibly make a caliper that small.
In a quantum mechanical Three Card Monte Game, you cannot be cheated, because all three cards are the same, and all three cards occupy all three positions at the same time.
And one of those times, it turned out the dishwasher was twins that were switching out when I was expediting.
/johnny
SC - In case no one informed you of this new science post.
The reason is that in classical physics, when you reconstruct a person out of all of the constituent leptons and quarks, it is not the same person, because even though the particles are the same mass, charge, density, and so on, it's still possible to say the reconstructed person is nothing more than a very precise clone.
But in quantum physics, if I have two leptons (electrons for example) or two down quarks and an up quark (neutron, for example) those particles are in a much deeper sense identical: there is no physical experiment that can "label" two electrons as distinct particles in a two electron system. There is no electron-1 and elecvtron-2. There is just "two electrons."
So (his argument goes) when God reconstructs a person from quantum particles (all questions of whether he has a soul or not aside), it isn't just a perfect identical twin. It is literally the same person.
It’s a fundamental asymmetry in the universe: I, on the other hand have had to cook quite often.
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