Flip Tanedo
@fliptanedo.bsky.social
Particle physicist. Flip spends his time thinking about dark matter while covered in chalk dust. https://particle.ucr.edu
The remaining term is proportional to the curvature tensor with its three lower indices antisymmetrized (blue). The entire quantity is zero (first step) and for any scalar (dot) or vector (circle), thus the blue highlighted piece must vanish. This proves the assertion.
April 5, 2025 at 9:56 PM
The remaining term is proportional to the curvature tensor with its three lower indices antisymmetrized (blue). The entire quantity is zero (first step) and for any scalar (dot) or vector (circle), thus the blue highlighted piece must vanish. This proves the assertion.
All but the last term vanish: the first one from torsion freedom, and the second from a combined symmetrization and anti-symmetrization of the same pair of indices.
April 5, 2025 at 9:56 PM
All but the last term vanish: the first one from torsion freedom, and the second from a combined symmetrization and anti-symmetrization of the same pair of indices.
Apply the chain rule for the inner (highlighted in blue) covariant derivative. This means the dashed blue circle is applied to each node inside it.
April 5, 2025 at 9:56 PM
Apply the chain rule for the inner (highlighted in blue) covariant derivative. This means the dashed blue circle is applied to each node inside it.
The first step, following a hint from Penrose's book, is to evaluate the following quantity for some arbitrary vector field (ξ) and scalar field (φ).
By the torsion free condition (highlighted in yellow) this quantity is zero. Next we expand the left-hand side.
By the torsion free condition (highlighted in yellow) this quantity is zero. Next we expand the left-hand side.
April 5, 2025 at 9:56 PM
The first step, following a hint from Penrose's book, is to evaluate the following quantity for some arbitrary vector field (ξ) and scalar field (φ).
By the torsion free condition (highlighted in yellow) this quantity is zero. Next we expand the left-hand side.
By the torsion free condition (highlighted in yellow) this quantity is zero. Next we expand the left-hand side.
The (Riemann) curvature is analogously defined from an antisymmetric covariant derivative.
April 5, 2025 at 9:56 PM
The (Riemann) curvature is analogously defined from an antisymmetric covariant derivative.
The torsion free condition is that the antisymmetric second derivative of a scalar vanishes.
April 5, 2025 at 9:56 PM
The torsion free condition is that the antisymmetric second derivative of a scalar vanishes.
Wigglies (bars) indicate (anti-)symmetrization of indices.
April 5, 2025 at 9:56 PM
Wigglies (bars) indicate (anti-)symmetrization of indices.
Covariant derivatives are dashed circles.
April 5, 2025 at 9:56 PM
Covariant derivatives are dashed circles.
Some notational background: Tensors are nodes and indices are lines. Lines that connect nodes are contracted.
April 5, 2025 at 9:56 PM
Some notational background: Tensors are nodes and indices are lines. Lines that connect nodes are contracted.
Here's an application of birdtrack notation to prove a curvature tensor identity. It is identical to index notation, but I find the diagrammatic proof easier to follow once I picked up the rules.
This is a solution to exercise [14.10] in Penrose's Road to Reality.
This is a solution to exercise [14.10] in Penrose's Road to Reality.
April 5, 2025 at 9:56 PM
Here's an application of birdtrack notation to prove a curvature tensor identity. It is identical to index notation, but I find the diagrammatic proof easier to follow once I picked up the rules.
This is a solution to exercise [14.10] in Penrose's Road to Reality.
This is a solution to exercise [14.10] in Penrose's Road to Reality.
This month and next month our Phy-Sci Book club is reading a couple of books ahead of Earth Day.
Next week we're discussing Rachel Carson's classic, Silent Spring. The book continues to hold its own as remarkable feat of accessible science writing 63 years after its original publication.
Next week we're discussing Rachel Carson's classic, Silent Spring. The book continues to hold its own as remarkable feat of accessible science writing 63 years after its original publication.
March 17, 2025 at 7:09 PM
This month and next month our Phy-Sci Book club is reading a couple of books ahead of Earth Day.
Next week we're discussing Rachel Carson's classic, Silent Spring. The book continues to hold its own as remarkable feat of accessible science writing 63 years after its original publication.
Next week we're discussing Rachel Carson's classic, Silent Spring. The book continues to hold its own as remarkable feat of accessible science writing 63 years after its original publication.
The lectures begin from causality and the analytic properties of the classical Green's function for the harmonic oscillator, and builds up towards the present S-matrix bootstrap program.
February 14, 2025 at 5:40 PM
The lectures begin from causality and the analytic properties of the classical Green's function for the harmonic oscillator, and builds up towards the present S-matrix bootstrap program.
The attendees included my own high school science teacher, Altair Maine (North Hollywood High School, LAUSD); and a @ucriverside.bsky.social physics alumnus Adam Christensen (King High School, RUSD), who was in some of the first courses I taught at UCR.
February 9, 2025 at 4:04 PM
The attendees included my own high school science teacher, Altair Maine (North Hollywood High School, LAUSD); and a @ucriverside.bsky.social physics alumnus Adam Christensen (King High School, RUSD), who was in some of the first courses I taught at UCR.
The recorded talks are available here
online.kitp.ucsb.edu/online/parti...
We had a fantastic lineup of speakers.
online.kitp.ucsb.edu/online/parti...
We had a fantastic lineup of speakers.
February 9, 2025 at 4:04 PM
The recorded talks are available here
online.kitp.ucsb.edu/online/parti...
We had a fantastic lineup of speakers.
online.kitp.ucsb.edu/online/parti...
We had a fantastic lineup of speakers.
Yesterday we had a fantastic Teachers' Conference at @kitp-ucsb.bsky.social, "This is Particle Theory."
The event brings together high school physics teachers to connect to the big ideas in research at the KITP. This year it was associated with our "What is Particle Theory" workshop.
The event brings together high school physics teachers to connect to the big ideas in research at the KITP. This year it was associated with our "What is Particle Theory" workshop.
February 9, 2025 at 4:04 PM
Yesterday we had a fantastic Teachers' Conference at @kitp-ucsb.bsky.social, "This is Particle Theory."
The event brings together high school physics teachers to connect to the big ideas in research at the KITP. This year it was associated with our "What is Particle Theory" workshop.
The event brings together high school physics teachers to connect to the big ideas in research at the KITP. This year it was associated with our "What is Particle Theory" workshop.
The details.
n.b. I am not affiliated with IAIFI or the school, just passing along the opportunity.
Application: iaifi.org/phd-summer-s...
n.b. I am not affiliated with IAIFI or the school, just passing along the opportunity.
Application: iaifi.org/phd-summer-s...
February 3, 2025 at 7:11 PM
The details.
n.b. I am not affiliated with IAIFI or the school, just passing along the opportunity.
Application: iaifi.org/phd-summer-s...
n.b. I am not affiliated with IAIFI or the school, just passing along the opportunity.
Application: iaifi.org/phd-summer-s...
Applications are open for the IAIFI Summer School on AI+Physics. iaifi.org/phd-summer-s...
#physics #machine-learning
#physics #machine-learning
February 3, 2025 at 7:11 PM
Applications are open for the IAIFI Summer School on AI+Physics. iaifi.org/phd-summer-s...
#physics #machine-learning
#physics #machine-learning
... I was reminded of this old New Yorker cartoon, which has been lightly adapted.
Original from: Paul Noth (www.paulnoth.com) 2011 ("Nobody ever asks *how* is Waldo.")
Original from: Paul Noth (www.paulnoth.com) 2011 ("Nobody ever asks *how* is Waldo.")
February 1, 2025 at 3:58 PM
... I was reminded of this old New Yorker cartoon, which has been lightly adapted.
Original from: Paul Noth (www.paulnoth.com) 2011 ("Nobody ever asks *how* is Waldo.")
Original from: Paul Noth (www.paulnoth.com) 2011 ("Nobody ever asks *how* is Waldo.")
... it has also created a theme for all program-related activities. Social events include "What is barbecue?" "What is [Joe's] bike ride?" "What is margarita?" and "What is pub quiz?"
February 1, 2025 at 3:58 PM
... it has also created a theme for all program-related activities. Social events include "What is barbecue?" "What is [Joe's] bike ride?" "What is margarita?" and "What is pub quiz?"
January 11, 2024 at 5:57 PM
The @nytimes.com highlights CERN as one of the "52 places to go in 2024."
nytimes.com/interactive/...
nytimes.com/interactive/...
January 10, 2024 at 4:23 PM
The @nytimes.com highlights CERN as one of the "52 places to go in 2024."
nytimes.com/interactive/...
nytimes.com/interactive/...
This is part of our [relatively] new UCR course, Physics 17: Linear Algebra for Physicists course, next offered in Spring 2024. sites.google.com/ucr.edu/phys...
[Forgive the typos in the table below. I'll leave it to my students to catch them later.]
[Forgive the typos in the table below. I'll leave it to my students to catch them later.]
December 20, 2023 at 6:03 AM
This is part of our [relatively] new UCR course, Physics 17: Linear Algebra for Physicists course, next offered in Spring 2024. sites.google.com/ucr.edu/phys...
[Forgive the typos in the table below. I'll leave it to my students to catch them later.]
[Forgive the typos in the table below. I'll leave it to my students to catch them later.]
We can write the general definition of the adjoint in my birdtracks-variant notation like this. The dashed lines are barred (conjugated) indices.
December 20, 2023 at 6:02 AM
We can write the general definition of the adjoint in my birdtracks-variant notation like this. The dashed lines are barred (conjugated) indices.
The condition for isometries in complex space takes the same form as we saw for real space. This condition is the familiar one for unitary matrices.
December 20, 2023 at 6:02 AM
The condition for isometries in complex space takes the same form as we saw for real space. This condition is the familiar one for unitary matrices.
If the metric is the identity, then the adjoint is the conjugate-transpose in matrix notation. This is physicists call this the Hermitian conjugate and are introduced to it in quantum mechanics.
December 20, 2023 at 6:01 AM
If the metric is the identity, then the adjoint is the conjugate-transpose in matrix notation. This is physicists call this the Hermitian conjugate and are introduced to it in quantum mechanics.