Student Forever
@agelessstudent.bsky.social
Retired. Now back to my first passion that led me to PhD in physics. Never stop learning, my friends!
Pinned
A year ago, retired as “tech fellow” after moderately successful career in software, I humbled myself to study, to fill in the gaps left over when I got my PhD long ago. More intense that grad school was and the most fun I’ve ever had.
The journey is beautiful no matter where you are in life.
The journey is beautiful no matter where you are in life.
Just for fun, Intensity I for radiation of frequency ν in direction ω obeys:
d𝐼 /ds =-κρ𝐼 + κρ 𝒥
𝒥 = ∫ p(ω,ω')𝐼(ω') dω'/4π
Solve for I with the right boundary conditions and you get the greenhouse effect in a scattering atmosphere.
d𝐼 /ds =-κρ𝐼 + κρ 𝒥
𝒥 = ∫ p(ω,ω')𝐼(ω') dω'/4π
Solve for I with the right boundary conditions and you get the greenhouse effect in a scattering atmosphere.
December 6, 2025 at 5:22 PM
Just for fun, Intensity I for radiation of frequency ν in direction ω obeys:
d𝐼 /ds =-κρ𝐼 + κρ 𝒥
𝒥 = ∫ p(ω,ω')𝐼(ω') dω'/4π
Solve for I with the right boundary conditions and you get the greenhouse effect in a scattering atmosphere.
d𝐼 /ds =-κρ𝐼 + κρ 𝒥
𝒥 = ∫ p(ω,ω')𝐼(ω') dω'/4π
Solve for I with the right boundary conditions and you get the greenhouse effect in a scattering atmosphere.
Why the interest in AdS/CFT duality? Heard this in a class:
In GR local energy is not well-defined. But if the spacetime far away from matter is AdS and we DO have a conserved energy.
That means a Hamiltonian - and a possible QM.
GR in bulk, QM on boundary. Hm, perhaps it is a duality...
In GR local energy is not well-defined. But if the spacetime far away from matter is AdS and we DO have a conserved energy.
That means a Hamiltonian - and a possible QM.
GR in bulk, QM on boundary. Hm, perhaps it is a duality...
November 4, 2025 at 7:56 PM
Why the interest in AdS/CFT duality? Heard this in a class:
In GR local energy is not well-defined. But if the spacetime far away from matter is AdS and we DO have a conserved energy.
That means a Hamiltonian - and a possible QM.
GR in bulk, QM on boundary. Hm, perhaps it is a duality...
In GR local energy is not well-defined. But if the spacetime far away from matter is AdS and we DO have a conserved energy.
That means a Hamiltonian - and a possible QM.
GR in bulk, QM on boundary. Hm, perhaps it is a duality...
I was doom-scrolling X this morning: it seems that MAGA has decided that Terrence Tao is an idiot, because he worries that he might have to leave the US due to funding issues.
I’m starting to worry myself, but about the future of this nation.
I’m starting to worry myself, but about the future of this nation.
November 1, 2025 at 1:56 PM
I was doom-scrolling X this morning: it seems that MAGA has decided that Terrence Tao is an idiot, because he worries that he might have to leave the US due to funding issues.
I’m starting to worry myself, but about the future of this nation.
I’m starting to worry myself, but about the future of this nation.
A year ago, retired as “tech fellow” after moderately successful career in software, I humbled myself to study, to fill in the gaps left over when I got my PhD long ago. More intense that grad school was and the most fun I’ve ever had.
The journey is beautiful no matter where you are in life.
The journey is beautiful no matter where you are in life.
October 22, 2025 at 10:06 PM
A year ago, retired as “tech fellow” after moderately successful career in software, I humbled myself to study, to fill in the gaps left over when I got my PhD long ago. More intense that grad school was and the most fun I’ve ever had.
The journey is beautiful no matter where you are in life.
The journey is beautiful no matter where you are in life.
Another math koan. Left hand side, purely classical probability vector. Right hand side, an inner product of purely quantum quantities: measurement operator μ and density operator ρ
How can this fundamental theorem of quantum information be so simple and yet so subtle?
How can this fundamental theorem of quantum information be so simple and yet so subtle?
October 9, 2025 at 10:01 PM
Another math koan. Left hand side, purely classical probability vector. Right hand side, an inner product of purely quantum quantities: measurement operator μ and density operator ρ
How can this fundamental theorem of quantum information be so simple and yet so subtle?
How can this fundamental theorem of quantum information be so simple and yet so subtle?
Got my Covid booster today. I’m feeling stronger already.
October 8, 2025 at 9:55 PM
Got my Covid booster today. I’m feeling stronger already.
Has anybody noticed that MAGA has become unbelievably hateful even to apolitical scientist-types like me?
September 26, 2025 at 10:52 PM
Has anybody noticed that MAGA has become unbelievably hateful even to apolitical scientist-types like me?
If you are looking for a nice online intro into general relativity, this one is good.
ocw.mit.edu/courses/8-96...
ocw.mit.edu/courses/8-96...
General Relativity | Physics | MIT OpenCourseWare
8.962 is MIT's graduate course in general relativity, which covers the basic principles of Einstein's general theory of relativity, differential geometry, experimental tests of general relativity, bla...
ocw.mit.edu
May 30, 2025 at 1:41 PM
If you are looking for a nice online intro into general relativity, this one is good.
ocw.mit.edu/courses/8-96...
ocw.mit.edu/courses/8-96...
The universe would make a lot more sense if they confirmed the existence of RR charge. I’m not holding my breath but if it’s out there eventually somebody will figure out a way of detecting it.
May 14, 2025 at 5:12 PM
The universe would make a lot more sense if they confirmed the existence of RR charge. I’m not holding my breath but if it’s out there eventually somebody will figure out a way of detecting it.
Today I checked off a major life bucket-list item. Not a much of an accomplishment and it took ten months. Just a deeper dive into a topic that had not satisfied me in grad school. But satisfying to come back to finish it, even 26 years later.
Sometimes are worth doing just because you want to!
Sometimes are worth doing just because you want to!
May 11, 2025 at 2:04 AM
Today I checked off a major life bucket-list item. Not a much of an accomplishment and it took ten months. Just a deeper dive into a topic that had not satisfied me in grad school. But satisfying to come back to finish it, even 26 years later.
Sometimes are worth doing just because you want to!
Sometimes are worth doing just because you want to!
All vaccines are tested with placebo before being approved by the FDA. Just go to clinicaltrials.gov and see for yourself.
Here is Moderna Covid vaccine:
clinicaltrials.gov/study/NCT044...
Here is Moderna Covid vaccine:
clinicaltrials.gov/study/NCT044...
ClinicalTrials.gov
clinicaltrials.gov
May 2, 2025 at 1:00 PM
All vaccines are tested with placebo before being approved by the FDA. Just go to clinicaltrials.gov and see for yourself.
Here is Moderna Covid vaccine:
clinicaltrials.gov/study/NCT044...
Here is Moderna Covid vaccine:
clinicaltrials.gov/study/NCT044...
A physics question. True or false: a functional of quantum fields is the Schroedinger representation of a state.
April 12, 2025 at 1:52 PM
A physics question. True or false: a functional of quantum fields is the Schroedinger representation of a state.
When I took my first physics class in 1978, after test review Dr Lloyd was fond of saying “You could write all the theory on a post card home and still have room to ask your folks for money.”
He was right. That’s still what I love about physics.
Is there any other field where this is true?
He was right. That’s still what I love about physics.
Is there any other field where this is true?
March 17, 2025 at 2:49 AM
When I took my first physics class in 1978, after test review Dr Lloyd was fond of saying “You could write all the theory on a post card home and still have room to ask your folks for money.”
He was right. That’s still what I love about physics.
Is there any other field where this is true?
He was right. That’s still what I love about physics.
Is there any other field where this is true?
Watching the anti-science faction taking over HHS I’m reminded of this:
“How long will you clueless people love your naïveté, mockers hold their mocking dear, and fools hate knowledge?”
— Proverbs 1:22
What can we do? All I can see is to be the voice of reason and hope some of it sticks.
“How long will you clueless people love your naïveté, mockers hold their mocking dear, and fools hate knowledge?”
— Proverbs 1:22
What can we do? All I can see is to be the voice of reason and hope some of it sticks.
March 14, 2025 at 11:46 PM
Watching the anti-science faction taking over HHS I’m reminded of this:
“How long will you clueless people love your naïveté, mockers hold their mocking dear, and fools hate knowledge?”
— Proverbs 1:22
What can we do? All I can see is to be the voice of reason and hope some of it sticks.
“How long will you clueless people love your naïveté, mockers hold their mocking dear, and fools hate knowledge?”
— Proverbs 1:22
What can we do? All I can see is to be the voice of reason and hope some of it sticks.
Just to take my mind of off the stock market crash, here is my entry for the weirdest way to write a second order ordinary differential equation:
March 11, 2025 at 6:32 PM
Just to take my mind of off the stock market crash, here is my entry for the weirdest way to write a second order ordinary differential equation:
I know everybody is freaking out about politics right now and understand why, but physics geeks freak out about other things.
Wanna freak out a phys grad student? Ask about Grassman numbers and Berezin integrals and why can you use them in path integrals. Then suggest to him he’s overthinking it.
Wanna freak out a phys grad student? Ask about Grassman numbers and Berezin integrals and why can you use them in path integrals. Then suggest to him he’s overthinking it.
January 20, 2025 at 12:06 AM
I know everybody is freaking out about politics right now and understand why, but physics geeks freak out about other things.
Wanna freak out a phys grad student? Ask about Grassman numbers and Berezin integrals and why can you use them in path integrals. Then suggest to him he’s overthinking it.
Wanna freak out a phys grad student? Ask about Grassman numbers and Berezin integrals and why can you use them in path integrals. Then suggest to him he’s overthinking it.
A physics riddle. What do you have to fix because it ISN’T broken?
January 14, 2025 at 4:27 PM
A physics riddle. What do you have to fix because it ISN’T broken?
“It is essential that the scientific community — and the public at large — support leaders who pledge to embrace evidence based decision making in science and public health” — Anthony Fauci.
Folks this is an objective fitness test for office. We should insist on it!
Folks this is an objective fitness test for office. We should insist on it!
January 7, 2025 at 2:34 PM
“It is essential that the scientific community — and the public at large — support leaders who pledge to embrace evidence based decision making in science and public health” — Anthony Fauci.
Folks this is an objective fitness test for office. We should insist on it!
Folks this is an objective fitness test for office. We should insist on it!
Someday I really want to understand string theory. Today I was trying to grok ch. 10 of Polchinski but I just could not concentrate. Turns out it was only because my blood pressure was really high like 206/112. What a relief!
January 7, 2025 at 1:01 AM
Someday I really want to understand string theory. Today I was trying to grok ch. 10 of Polchinski but I just could not concentrate. Turns out it was only because my blood pressure was really high like 206/112. What a relief!
It is coming up on six months into my retirement, formerly a principle engineer, or IT Tech Fellow, depending on the timing. I’m very happy. Is this unusual?
January 6, 2025 at 2:33 AM
It is coming up on six months into my retirement, formerly a principle engineer, or IT Tech Fellow, depending on the timing. I’m very happy. Is this unusual?
The fundamental group for an ordinary plane has just one member: the zero element. Remove a single point and the group has infinite number of elements: one for each integer. The tiniest flaw has infinite repercussions.
No wonder mathematicians are sometimes perfectionists.
No wonder mathematicians are sometimes perfectionists.
December 21, 2024 at 7:27 PM
The fundamental group for an ordinary plane has just one member: the zero element. Remove a single point and the group has infinite number of elements: one for each integer. The tiniest flaw has infinite repercussions.
No wonder mathematicians are sometimes perfectionists.
No wonder mathematicians are sometimes perfectionists.
homotopy is used to study groups of loops based on topology. It has many applications to physics
I stumbled on to an excellent intro to homotopy and fundamental groups people.math.harvard.edu/~landesman/a...
Easy to read and makes few assumptions about prior knowledge.
Happy studying!
I stumbled on to an excellent intro to homotopy and fundamental groups people.math.harvard.edu/~landesman/a...
Easy to read and makes few assumptions about prior knowledge.
Happy studying!
people.math.harvard.edu
December 19, 2024 at 5:06 PM
homotopy is used to study groups of loops based on topology. It has many applications to physics
I stumbled on to an excellent intro to homotopy and fundamental groups people.math.harvard.edu/~landesman/a...
Easy to read and makes few assumptions about prior knowledge.
Happy studying!
I stumbled on to an excellent intro to homotopy and fundamental groups people.math.harvard.edu/~landesman/a...
Easy to read and makes few assumptions about prior knowledge.
Happy studying!
I’m not too proud to take delight in learning new things even if — especially if — it’s something I should already know. Arrogance and pride are great barriers to a richer life. Please do not ever fall into that trap!
December 16, 2024 at 2:27 PM
I’m not too proud to take delight in learning new things even if — especially if — it’s something I should already know. Arrogance and pride are great barriers to a richer life. Please do not ever fall into that trap!
I like x for grok:
Hey Grok: the parallel transport map of a given connection, acting on the set of all closed paths on a vector bundle and containing any fixed point, forms a Lie group under composition of the map, called the holonomy group. Draw an illustration using cats.
Hey Grok: the parallel transport map of a given connection, acting on the set of all closed paths on a vector bundle and containing any fixed point, forms a Lie group under composition of the map, called the holonomy group. Draw an illustration using cats.
December 15, 2024 at 1:30 AM
I like x for grok:
Hey Grok: the parallel transport map of a given connection, acting on the set of all closed paths on a vector bundle and containing any fixed point, forms a Lie group under composition of the map, called the holonomy group. Draw an illustration using cats.
Hey Grok: the parallel transport map of a given connection, acting on the set of all closed paths on a vector bundle and containing any fixed point, forms a Lie group under composition of the map, called the holonomy group. Draw an illustration using cats.
A bot on X asked me “what’s the most mind blowing thing you’ve learned” Such an intriguing question I had to answer. It’s the “holographic principle” — the idea that our universe is like the inside of a soap bubble, filled with nothing but projection of fields living only on the bubble surface. 1/2
December 14, 2024 at 12:00 AM
A bot on X asked me “what’s the most mind blowing thing you’ve learned” Such an intriguing question I had to answer. It’s the “holographic principle” — the idea that our universe is like the inside of a soap bubble, filled with nothing but projection of fields living only on the bubble surface. 1/2