Dirac on Theoretical Physics

Here's a video clip of Paul A.M. Dirac explaining how theoretical physicists worked -- or, at least, how HE worked:

 

He was British, and his full name was Paul Adrien Maurice Dirac. I'm surprised I still remember that.

The Schrodinger equation wasn't consistent with Einstein's special relativity. Among other things, it got the spin of the electron wrong. (In fact, Schrodinger didn't include spin at all.)

Dirac derived the relativistic Schrodinger equation, consistent with Einstein, and, miraculously, it correctly predicted the spin of the electron (within a few percent; quantum electrodynamics--the field theory of relativistic quantum mechanics--would do the rest). Here's what Dirac's equation looked like:

That's kind of messy, though the Wiki page explains it. Psi is the usual wave function of quantum mechanics, although in Dirac's theory it's a 4-dimensionl vector. (In Schrodinger it's just a regular function over all of space and time, what physicists call a "scalar.") But my generation, and the one before, and those following know it as:

It's just mathematically simpler. Moreover, now we set c=1 (the speed of light), and, for that matter, G=hbar=k=1, where G is Newton's gravitational constant, hbar is Planck's constant divided by 2*pi, and k is Boltzmann's constant. These constants simply set the scale of dimensions, and can always be added back if you're looking for real-world predictions.

{If you're said it will take you "an hour" (or whatever) to drive from home to you grandma's, you did the same thing with units, taking your velocity to be =1.}

I don't think I've ever solved the Dirac equation except for a free electron, as has every other graduate student in physics, but I once saw a PhD dissertation that solved it for the hydrogen atom. It was nontrivial.)

Anyway...when he was a young physicist in Europe, Dirac derived his equation from general considerations, a real tour-de-force of both quantum mechanics, special relativity and mathematics for its time. It was better than Schrodinger.

Dirac was a little weird, no doubt an advantage:

His colleagues in Cambridge jokingly defined a unit called a "dirac", which was one word per hour.

This likely contributed to his great success. Dirac put forth his equation in 1928, and by 1933 won the Nobel Prize in physics, along with Schrodinger. Dirac has just turned 32 years old.

Wiki:

"After having relocated to Florida to be near his elder daughter, Mary, Dirac spent his last fourteen years of both life and physics research at the University of Miami in Coral Gables, Florida, and Florida State University in Tallahassee, Florida."

Dirac did other notable work besides his relativistic wave equation, but nothing on its scale, and it's what he will forever be known for. 

So I found it really interesting to watch him talk about what made him tick.   

An Unexpected iPhone Issue

I found an unexpected...issue...with iPhone's Siri when I asked it to do a calculation: It doesn't understand scientific notation. 

I wanted to know the ratio of the mass of Jupiter to the mass of the Earth, so I asked Siri to calculate it. I gave it instrutions:

"Hey Siri, divide one point nine times ten to the twenty-seventh by five point nine seven times ten to the twenty-fourth."

It returned 3.18 x 10⁵⁰, when the correct answer is 318.

It took me a minute to figure out that the calculation it did was

(1.9)*(10²⁷)÷(5.97)*(10²⁴)

which gives 0.31825 x 10⁵¹, which after adjusting the decimal point is the number it gave.

 
Siri treated multiplication and division equally, on the same level. It doesn't understand scientific notation. I really didn't expect that. But maybe I should have.

Nor does it understand a number in the form "one point nine e twenty-seven". She doesn't understand the "e".

It also gives the wrong answer, albeit a different answer, if you rotate the iPhone to the screen with the advanced functions and speak to it. 

For some reason it now took "e 27" to be 10^{20/7}, but got "e 24" correct as 10²⁴.

Now I know. But I hope someone on a project team, when rushing during a dire crisis, doesn't use Siri to calculate a rocket trajectory or whatnot.  

Good Bones

By Maggie Smith 

"Life is short, though I keep this from my children.
Life is short, and I’ve shortened mine
in a thousand delicious, ill-advised ways,
a thousand deliciously ill-advised ways
I’ll keep from my children. The world is at least
fifty percent terrible, and that’s a conservative
estimate, though I keep this from my children.
For every bird there is a stone thrown at a bird.
For every loved child, a child broken, bagged,
sunk in a lake. Life is short and the world
is at least half terrible, and for every kind
stranger, there is one who would break you,
though I keep this from my children. I am trying
to sell them the world. Any decent realtor,
walking you through a real shithole, chirps on
about good bones: This place could be beautiful,
right? You could make this place beautiful."

Via the Poetry Foundation

Warning About Blogging

Blogger was abandoned by Google a few years ago, and lately it's been getting worse and worse. A lot of problems. It's becoming so bad it may have to be abandoned soon. Just much more trouble than solution.

I'm not going to try to port all this to, I guess, Wordpress. Too much hassle, if it worked even a bit.

I don't have the enthusiasm anymore anyhow.

Bradbury Quote

“You don’t have to burn books to destroy a culture. Just get people to stop reading them.”

Ray Bradbury

I don't think he wrote this in his book Fahrenheit 451. I guess perhaps in an interview about it.

I just read 451°F two years ago. Never read it when I was younger, or was made to. Should have been much earlier. A good book that ended in a way I hadn't anticipated.

Did you know he wrote this book in 9 days? On a typewriter he rented by the hour at a local university?

Where US Coastal Land is Sinking

-4 to -6 mm/yr in a few places. Some less all across the Gulf Coast, and in many places along the Atlantic coast.

      

Source: 

CNN, 06 March 2024. 

https://www.cnn.com/2024/03/06/climate/sinking-cities-us-sea-level-rise-climate/index.html

Biden Lost Market Share (Big-Time)

The PredictIt betting market on the US presidential race:

"...Will Not Be Able to Show Their Faces"

Thomas Friedman with some pretty sober words in today's NY Times (free link):

"But if he [Biden] caps his presidency now, by acknowledging that because of age he is not up to a second term, his first and only term will be remembered as among the better presidencies in our history. He saved us from a second Trump term, and for that alone he deserves the Presidential Medal of Freedom, but he also enacted important legislation crucial to confronting the climate and technology revolutions now upon us.

"I had been ready to give Biden the benefit of the doubt up to now, because during the times I engaged with him one on one, I found him up to the job. He clearly is not any longer. His family and his staff had to have known that. They have been holed up at Camp David preparing for this momentous debate for days now. If that is the best performance they could summon from him, it’s time for him to keep the dignity he deserves and leave the stage at the end of this term.

"If he does, everyday Americans will hail Joe Biden for doing what Donald Trump would never do: put the country before himself.

"If he insists on running and he loses to Trump, Biden and his family — and his staff and party members who enabled him — will not be able to show their faces."

Debate Notes (PS: Yikes)

• 6:04 pm Pacific Daylight Time - Jesus, Biden sounds old. His voice isn't clear, he sounds almost sick. Not a good look sound.
• 6:11 pm - Trump says "we're like a third world country." {ludicrous eye roll}
• 6:15 pm - Trump says "every legal scholar" wanted Roe v Wade repealed (viz., abortion policies returned to the states). Massive lie. He says "they take the life of the baby after birth." Another massive lie. 
• 6:18 pm - Trump again says "every legal scholar" wanted Roe v Wade repealed. 
• 6:22 pm - Did Trump just call him "Brandon??"
• 6:25 pm - Trump: "We're literally an uncivilized society."
• 6:26 pm - Biden: "Everything he just said is a lie." That's more like it.
• 6:31 pm - Biden: "I've never heard so much malarky in my life."😉
• 6:40 pm - Trump makes January 6th sound like a peak instance of America in the world.
• 6:46 pm - Trump: "Joe could be a convicted felon as soon as he gets out of office.... This man is a criminal.... I did nothing wrong."
• 6:49 pm - Biden: "This guy has no sense of American democracy."
• 6:52 pm - Biden has a powerful line: "40 of 44 of his top cabinet officials have refused to endorse him this time." 
• "6:59 pm - Trump says "cost of food has doubled, tripled, quadrupled."
• "7:02 pm - Trump is very obviously avoiding talking about climate change. Now he says he wants "immaculately clean water and clean air." He either doesn't understand climate change at all or prefers to lie about it. Or some/any combination of both.
• Biden says: "He just doesn't know what he's talking about," by he says it weakly, with a very thin breath. Just not a good look. Where is the Biden who gave the State of the Union address in March??
• Trump has the nerve to say, "Everything he says is a lie."
• Trump says he just won "two club championships" in golf. LOLOLOL
• Biden: "You're a whiner... You're such a whiner.... Something snapped in your last time." Funny. 

Summary: 

If I had to score this, in terms of both content and quality, I’d say Trump 60% - Biden 40%. I don’t like that at all, but to me Biden came across as old, kind of frail, and faint. It didn’t help that he often slurs his words, and occasionally starts a sentence that then meanders off into nowhere. His voice is gravelly and that sounds old. Trump gave almost no coherent replies, his words seem to follow a mind stuck in a washing machine. He was full of hyperbolic statements, and seemed to avoid giving any data or figures at all. He just doesn’t have a grasp on information of that sort.

My guess is that the majority of the public is going to decide that Trump “won.” Biden just sounded weak. I’m sure the transcript would show Biden winning, but that’s not how this will be judged. I guess it never has been since JFK vs Nixon. 

A pundit on CNN says Democrats are “in panic…it started minutes into the debate.” Questions if they will go to the White House and ask Biden to step aside. Another says “the panic I’m hearing from Democrats is not something I have heard” before. “Concern there has been some real damage done.”

Now I’m worried Biden can’t win this. I though before this he probably could, but now he simply doesn’t look like he can serve another four years. Trump did look like he could. 

Another: “this was an unmitigated disaster for Biden.”

Last election Biden said he would only serve 4 years. He should have kept his promise. Let Gavin Newsom run (he’d beat Kamala Harris). Newsom would stand up directly and forcefully to Trump. Sure Newsom has a lot of baggage, but certainly not as much as Trump. Newsom would battle. Biden seems like he can’t. And Trump didn't look like an angry ape.

What do you all think?

--

Thinking about it more, I would say Trump 75% - Biden 25%. That bad. Biden may have just lost the election, and handed it to an incompetent, dangerous, buffoon.

China's Returned Lunar Capsule

Here is China’s Chang’e-6 re-entry capsule, containing about 2 kg of lunar regolith. Landed in inner Mongolia. Just surprised how burned up/beat up it is....

Via nature.com.

PS: Until today I thought "regolith" referred specifically to lunar material, but learned it is any loose material above a bedrock.

More Haj Deaths

Now over 900:

Death toll from heat at hajj pilgrimage in Saudi Arabia passes 900.... Temperatures hit 51.8°C in Mecca, Islam's holiest city, on Monday, as 1.8 million people took part in the annual pilgrimage...total reported dead so far to 922.... According to a Saudi study published last month, temperatures in the area are rising 0.4°C each decade. Last year more than 200 pilgrims were reported dead, most of them from Indonesia.

Source: Le Monde, yesterday

Update: CBS News now saysCBS News now says 1,081.

Haj Heat

“At least 562 people have died during the [2024] haj, according to a Reuters tally based on foreign ministry statements and sources. Egypt alone has registered 307 deaths and another 118 missing, medical and security sources told Reuters, as temperatures at times soared past 51 degrees Celsius (124 Fahrenheit).”

from “Climate change threat hangs over haj pilgrimage as hundreds perish in heat,” Reuters 6/19/24.

11 Extreme Cooling Events Over the Holocene

I wrote an article for Phys.org:

"Uncovering the prolonged cooling events of the Holocene," Phys.org, 6/13/24.

https://phys.org/news/2024-06-uncovering-prolonged-cooling-events-holocene.html

They were all caused by a group of volcanic eruptions over a short period of time (~decades) augmented by the ice-albedo feedback. Just like the Little Ice Age. The paper gives this graph for the 200-yr moving average of NH surface temperature of the last 6,000 years:

There were no prolonged natural warm periods.

I read the news today, oh boy

Here's what I posted last night, then accidentally deleted:

Here's what they wrote (it's still up):

While London was experiencing 32C (89.6F) a year ago, temperatures were around 16C (60.8F) in the capital on Tuesday. Similarly Cambridge had temperatures of 30.3C (86.5F) on June 11 2023, and 15C (59F) on the same day in 2024.

Of course, half of 32°C (=305 Kelvin) is 152.5 K, which is -121°C.

Notice their claim is bollocks in Fahrenheit. 

I wonder how many editors this article past through before publication. Not one caught this. Probably they never even heard of Kelvin nor understands what it means.