John C. Baez's Blog, page 37

Neutrino Puzzles (Part 1)

Merry Xmas, Ymas, and Zmas—and a variable New Year!

For a long time I’ve been meaning to update this list of open questions on the Physics FAQ:

• Open questions in physics, Physics FAQ.

Here’s what it said about neutrinos as of 2012:

• What is the correct theory of neutrinos?  Why are they almost but not quite massless?  Do all three known neutrinos—electron, muon, and tau—all have a mass?  Could any neutrinos be Majorana spinors?  Is there a fourth kind of neutrino, such as a “sterile” neutrin...

Neutrino Puzzles

Merry Xmas, Ymas, and Zmas—and a variable New Year!

For a long time I’ve been meaning to update this list of open questions on the Physics FAQ:

• Open questions in physics, Physics FAQ.

Here’s what it said about neutrinos as of 2012:

• What is the correct theory of neutrinos?  Why are they almost but not quite massless?  Do all three known neutrinos—electron, muon, and tau—all have a mass?  Could any neutrinos be Majorana spinors?  Is there a fourth kind of neutrino, such as a “sterile” neutrin...

Theoretical Physics in the 21st Century

In 2021, March 8–13 will be “Sustainability Week” in Switzerland. During this week, students at all Swiss universities will come together to present their current work, promote a sustainable lifestyle and draw extra attention to changes that must be made at the institutional level. Anna Knörr, a third year Physics Bachelor student at ETH Zürich, is president of the Student Sustainability Commission. She and Professor Niklas Beisert invited me to give the Zurich Theoretical Physics Colloquium o...

Consolidated Appropriations Act, 2021

You may not have noticed, but the US Congress just passed the biggest climate-related bill in long time, with measures to help save the ozone layer and speed progress on solar, wind and nuclear energy, battery storage and carbon capture. It’s big news, though it’s been overshadowed by the pandemic and resulting economic disaster. Everyone is focused on another portion of the 5593-page bill: Division M, the Coronavirus Response and Relief Supplemental Appropriations Act.

• Sarah Kaplan and Din...

Theories of Aether and Electricity (Part 1)

I’ve been reading an amazing book, a little bit every night in bed:

• Edmund Whittaker, A History of the Theories of Aether and Electricity, Two Volumes Bound As One. Volume I: The Classical Theories. Vol. II: The Modern Theories, 1900-1926. Dover, 1989, 753 pages.

How in the world did our species figure out the laws governing the electric field, magnetic field, and charged particles? A lot started with pure luck. Two unusual stones played a key role: amber and lodestone.

The first, really fos...

Ceres

On 11 December 2020, Ceres, a sustainability nonprofit that works with investors on climate change, announced that a consortium of 30 investors managing $9 trillion in assets have committed to investing to support the goal of net zero carbon emissions by 2050.

This is what the 30 investors signed:

The Net Zero Asset Managers Commitment

In line with the best available science on the impacts of climate change, we acknowledge that there is an urgent need to accelerate the transition towards global...

The Dome Fire

This August a fire swept through the Mojave National Preserve in southern California and killed about a million Joshua trees. Let us take a moment to mourn them, along with the ancient coastal redwoods and giant sequouias that we also lost this year.

John Branch, Theyre among the worlds oldest living things. The climate crisis is killing them, New York Times.

This lavishly illustrated article talks about all three species. Ill just quote the part on Joshua trees, since they live pretty...

US Fusion Reactor Plan

A while back I mentioned the SPARC fusion reactor, a relatively new design. What about more traditional approaches to fusion? Heres a good article about the state of funding for these in the US:

Adrian Cho, U.S. physicists rally around ambitious plan to build fusion power plant, Science, 8 December 2020.

Heres the start:

U.S. fusion scientists, notorious for squabbling over which projects to fund with their fields limited budget, have coalesced around an audacious goal. A 10-year plan...

Applied Compositional Thinking for Engineers

Hey! Theres a new online course coming up!

Applied Compositional Thinking for Engineers. January 7, 8, 11-15, 20-22, and 25-29. Taught by Andrea Censi, Jonathan Lorand and Gioele Zardini.

Its not a coincidence that the acronym for Compositional Thinking is CT, just like Category Theory.

The course is free but registration is required. During the sign-up process you will be asked for the most convenient times for you; the instructors will choose what works best for a majority of participants....

Great Conjunction

Ive been seeing Saturn and Jupiter coming closer to each other in the sky lately. Jupiter passes by Saturn every 19.6 years, and its called a great conjunction. But I just learned that on December 21st theyll look closer than they have since March 1226! Theyll be just 0.1 degrees apart: 6.1 arcminutes, to be precise. Thats less than a fifth of the Moons apparent width.

Jupiter and Saturn were even closer on July 17, 1623just 5.2 arcminutes apartbut the glare from the the Sun made them...