KREUZADER (Posts tagged physics)

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“An image of a single positively-charged strontium atom, held near motionless by electric fields, has won the overall prize in a national science photography competition, organised by the Engineering and Physical Sciences Research Council...

An image of a single positively-charged strontium atom, held near motionless by electric fields, has won the overall prize in a national science photography competition, organised by the Engineering and Physical Sciences Research Council (EPSRC).

‘Single Atom in an Ion Trap’, by David Nadlinger, from the University of Oxford, shows the atom held by the fields emanating from the metal electrodes surrounding it. The distance between the small needle tips is about two millimetres.

When illuminated by a laser of the right blue-violet colour the atom absorbs and re-emits light particles sufficiently quickly for an ordinary camera to capture it in a long exposure photograph. The winning picture was taken through a window of the ultra-high vacuum chamber that houses the ion trap.

Source: epsrc.ac.uk
photography physics
How the Universe Got Its Bounce Back“[…] in the past few years, a growing number of cosmologists have cautiously revisited the alternative. They say the Big Bang might instead have been a Big Bounce. Some cosmologists favor a picture in which the...

How the Universe Got Its Bounce Back

[…] in the past few years, a growing number of cosmologists have cautiously revisited the alternative. They say the Big Bang might instead have been a Big Bounce. Some cosmologists favor a picture in which the universe expands and contracts cyclically like a lung, bouncing each time it shrinks to a certain size, while others propose that the cosmos only bounced once — that it had been contracting, before the bounce, since the infinite past, and that it will expand forever after. In either model, time continues into the past and future without end.

[…]

Already, several groups are making progress at once. Most significantly, in the last year, physicists have come up with two new ways that bounces could conceivably occur. One of the models, described in a paper that will appear in the Journal of Cosmology and Astroparticle Physics, comes from Anna Ijjas of Columbia University, extending earlier work with her former adviser, the Princeton professor and high-profile bounce cosmologist Paul Steinhardt. More surprisingly, the other new bounce solution, accepted for publication in Physical Review D, was proposed by Peter Graham, David Kaplan and Surjeet Rajendran, a well-known trio of collaborators who mainly focus on particle physics questions and have no previous connection to the bounce cosmology community. It’s a noteworthy development in a field that’s highly polarized on the bang vs. bounce question.

Source: quantamagazine.org
physics cosmology
Universes with no weak force might still have stars and life“Not all fundamental forces are created equal. An alternate universe that lacks the weak nuclear force — one of the four fundamental forces that govern all matter in our universe — could...

Universes with no weak force might still have stars and life

Not all fundamental forces are created equal. An alternate universe that lacks the weak nuclear force — one of the four fundamental forces that govern all matter in our universe — could still form galaxies, stars, planets and perhaps life, according to calculations published online January 18 at arXiv.org.

Scientists have long thought that our universe wouldn’t exist, or at least wouldn’t support life, without certain physical laws. For instance, if gravity were much stronger than it is, most matter would collapse into black holes; if it were weaker, the universe wouldn’t form structures such as galaxies or planets. The strong nuclear force holds atomic nuclei together, and the electromagnetic force carries light across the universe.

“Those three forces, gravity, strong and electromagnetic, are part of the deal,” says theoretical physicist Fred Adams of the University of Michigan in Ann Arbor. But the weak nuclear force — responsible for making neutrons decay into protons, electrons and neutrinos — might not be so essential (SN: 4/29/17, p. 22). “That’s the only one you can get rid of entirely without messing everything up,” he says.

Source: sciencenews.org
physics cosmology
err, this is amazing if the math holds up: The Plasma Magnet Drive: A Simple, Cheap Drive for the Solar System and Beyond“The plasma magnet is a type of magsail that creates a kilometers wide, artificial magnetosphere that deflects the charged solar...

err, this is amazing if the math holds up:

The Plasma Magnet Drive: A Simple, Cheap Drive for the Solar System and Beyond

The plasma magnet is a type of magsail that creates a kilometers wide, artificial magnetosphere that deflects the charged solar wind to provide thrust.

Unlike a classic magsail that generates the magnetic field with a large diameter electrical circuit, the plasma magnet replaces the circular superconducting coil by inducing the current flow with the charged particles of the solar wind.  It is an upgraded development of Robert Winglee’s Mini-Magnetospheric Plasma Propulsion (M2P2), a drive that required injection of charged particles to generate the magnetosphere.

[…]

The plasma magnet, as a space drive, has much better thrust to weight ratio than even the new X-3 Hall Effect ion engine currently in development.  This ratio remains high when the power supply from solar array is added.  Of more importance is that the plasma magnet is theoretically propellantless, providing thrust as long as the solar wind is flowing past the craft and power is supplied.

Source: centauri-dreams.org
space physics
Neutrinos Suggest Solution to Mystery of Universe’s Existence“In this ongoing experiment, the first results of which were reported last year, scientists at T2K are studying the way these neutrinos flip in an effort to explain the predominance of...

Neutrinos Suggest Solution to Mystery of Universe’s Existence

In this ongoing experiment, the first results of which were reported last year, scientists at T2K are studying the way these neutrinos flip in an effort to explain the predominance of matter over antimatter in the universe. During my visit, physicists explained to me that an additional year’s worth of data was in, and that the results are encouraging.

According to the Standard Model of particle physics, every particle has a mirror-image particle that carries the opposite electrical charge — an antimatter particle. When matter and antimatter particles collide, they annihilate in a flash of radiation. Yet scientists believe that the Big Bang should have produced equal amounts of matter and antimatter, which would imply that everything should have vanished fairly quickly. But it didn’t.

[…]

Super-K captured 89 electron neutrinos, significantly more than the 67 it should have found if there was no CP violation. And the experiment spotted only seven electron antineutrinos, two fewer than expected.

Source: quantamagazine.org
antimatter physics
Measurement of the multi-TeV neutrino interaction cross-section with IceCube using Earth absorption“Neutrinos interact only very weakly, so they are extremely penetrating. The theoretical neutrino–nucleon interaction cross-section, however, increases...

Measurement of the multi-TeV neutrino interaction cross-section with IceCube using Earth absorption

Neutrinos interact only very weakly, so they are extremely penetrating. The theoretical neutrino–nucleon interaction cross-section, however, increases with increasing neutrino energy, and neutrinos with energies above 40 teraelectronvolts (TeV) are expected to be absorbed as they pass through the Earth. Experimentally, the cross-section has been determined only at the relatively low energies (below 0.4 TeV) that are available at neutrino beams from accelerators. Here we report a measurement of neutrino absorption by the Earth using a sample of 10,784 energetic upward-going neutrino-induced muons. The flux of high-energy neutrinos transiting long paths through the Earth is attenuated compared to a reference sample that follows shorter trajectories. Using a fit to the two-dimensional distribution of muon energy and zenith angle, we determine the neutrino–nucleon interaction cross-section for neutrino energies 6.3–980 TeV, more than an order of magnitude higher than previous measurements. The measured cross-section is about 1.3 times the prediction of the standard model, consistent with the expectations for charged- and neutral-current interactions. We do not observe a large increase in the cross-section with neutrino energy, in contrast with the predictions of some theoretical models, including those invoking more compact spatial dimensions or the production of leptoquarks. This cross-section measurement can be used to set limits on the existence of some hypothesized beyond-standard-model particles, including leptoquarks.

Source: nature.com
physics
Lightning strikes leave behind a radioactive cloud“Thunderstorms have a lot of overt indications of power, from the thunder and lightning to torrential rains and hail. But the full extent of their power wasn’t obvious until recent years, when we...

Lightning strikes leave behind a radioactive cloud

Thunderstorms have a lot of overt indications of power, from the thunder and lightning to torrential rains and hail. But the full extent of their power wasn’t obvious until recent years, when we discovered they generate antimatter. Now, researchers in Japan have looked at this phenomenon more closely and determined that a lightning bolt generates a zone that contains unstable isotopes of oxygen and nitrogen, leading to series of radioactive decays over the next minute.

Source: Ars Technica
physics weather lightning
Subatomic particles reveal a mysterious structure inside Giza’s Great Pyramid“A shower of subatomic particles has revealed the outlines of an empty cavity inside the Great Pyramid at Giza in Egypt — the first discovery of a new internal structure in...

Subatomic particles reveal a mysterious structure inside Giza’s Great Pyramid

A shower of subatomic particles has revealed the outlines of an empty cavity inside the Great Pyramid at Giza in Egypt — the first discovery of a new internal structure in almost two centuries. Scientists don’t know exactly what it is yet, or why it’s there. But the finding might help solve the mystery of how an ancient civilization constructed this imposing monument 4,500 years ago.

[…]

The research team found it by tracking particles called muons. Muons are produced when the cosmic rays that permeate our Universe and pummel our atmosphere break down — creating a kind of subatomic confetti that rains down on Earth at almost the speed of light. These particles drift through air more easily than they pass through solid objects like stone. So by analyzing how many muons travel through a massive object like a pyramid, scientists can detect internal gaps and spaces.

Source: theverge.com
pyramid physics