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Graduate Unexpected irregular reflection signal from a high-finesse cavity

51 minutes ago · Replies 0 · 51 minutes ago

Replies: 0

Views: 32

Intro

Today, 6:34 PM · Replies 1 · Today, 6:48 PM

Replies: 1

Views: 44

Today I Learned

Nov 20, 2014 · Replies 7K · Today, 6:39 PM

228

Replies: 7K

Views: 466K

I want to help Physics education. What should I do?

Jul 23, 2025 · Replies 74 · Today, 6:24 PM

3

Replies: 74

Views: 5K

Graduate Is the 2-qubit singlet state invariant under bilateral projections?

Today, 6:21 PM · Replies 0 · Today, 6:21 PM

Replies: 0

Views: 57

Music Who is your favorite Jazz musician and what is your favorite song?

Mar 31, 2023 · Replies 324 · Today, 5:37 PM

11

Replies: 324

Views: 23K

Music Cover songs versus the original track, which ones are better?

Feb 21, 2023 · Replies 2K · Today, 5:14 PM

75

Replies: 2K

Views: 104K

Engineering Half wave voltage doubler

Today, 8:29 AM · Replies 2 · Today, 2:30 PM

Replies: 2

Views: 125

Wordle Lovers - Play the NYT Daily Game

Jul 16, 2022 · Replies 8K · Today, 1:55 PM

268

Replies: 8K

Views: 240K

Announcement RIP Vanadium 50

Nov 12, 2025 · Replies 45 · Today, 1:35 PM

2

Replies: 45

Views: 4K

2025 Eruption of Mount Semeru on Indonesia

Nov 20, 2025 · Replies 1 · Today, 1:35 PM

Replies: 1

Views: 563

Graduate Two equivalent statements of time reversal symmetric Hamiltonian

Saturday, 4:01 AM · Replies 13 · Today, 1:21 PM

Replies: 13

Views: 485

Undergrad Train Wreck Integral Shortcut...

Today, 8:43 AM · Replies 3 · Today, 12:37 PM

Replies: 3

Views: 134

Undergrad Axial angular momentum calculation

Mar 8, 2025 · Replies 29 · Today, 12:01 PM

Replies: 29

Views: 2K

High School Does acceleration affect impact energy vs constant velocity?

Thursday, 9:05 AM · Replies 17 · Today, 12:01 PM

Replies: 17

Views: 876

Undergrad EPR revisited

Oct 31, 2025 · Replies 29 · Today, 10:45 AM

Replies: 29

Views: 1K

High School Estimates — True Size of the Universe?

Mar 19, 2025 · Replies 33 · Today, 10:13 AM

2

Replies: 33

Views: 5K

Wait 24 hours before powering up A/C or fridge?

Yesterday, 11:50 AM · Replies 15 · Today, 10:01 AM

Replies: 15

Views: 309

Great ebass playing

Nov 14, 2025 · Replies 82 · Today, 9:37 AM

3

Replies: 82

Views: 3K

New

Today, 9:25 AM · Replies 1 · Today, 9:28 AM

Replies: 1

Views: 67

Insights Quantum Entanglement is a Kinematic Fact, not a Dynamical Effect

Sep 2, 2025 · Replies 22 · Today, 9:24 AM

Replies: 22

Views: 5K

Collection of Lame Jokes

May 12, 2004 · Replies 24K · Today, 8:07 AM

788

Replies: 24K

Views: 2M

Complementary resources to Feynman Lectures

Jun 29, 2024 · Replies 13 · Today, 7:58 AM

Replies: 13

Views: 4K

Intro Physics What is the best conceptual high school physics book?

Yesterday, 6:28 PM · Replies 2 · Today, 7:23 AM

Replies: 2

Views: 218

History Interesting anecdotes in the history of physics?

Jan 20, 2024 · Replies 269 · Today, 6:46 AM

9

Replies: 269

Views: 24K

Graduate Dasgupta et al., What is the alternative to a unique dS vacua?

Dec 7, 2025 · Replies 13 · Today, 5:46 AM

Replies: 13

Views: 1K

Music What Happened to Talent?

Yesterday, 7:03 PM · Replies 5 · Today, 5:30 AM

Replies: 5

Views: 199

Distance between a Clock's hands when the distance is increasing most rapidly

Dec 7, 2025 · Replies 29 · Today, 4:45 AM

Replies: 29

Views: 2K

Poll

Other Sciences Award

Dec 16, 2025 · Replies 3 · Today, 4:23 AM

Replies: 3

Views: 295

Announcement PF Member Awards 2025 Coming Soon!

Nov 30, 2025 · Replies 7 · Today, 4:14 AM

Replies: 7

Views: 816

Neurosurgeon for understanding a bit

Saturday, 4:41 PM · Replies 9 · Today, 4:10 AM

Replies: 9

Views: 293

Construction How do I fix a hedgehog enclosure that keeps getting too humid

Yesterday, 10:43 AM · Replies 10 · Today, 3:16 AM

Replies: 10

Views: 331

Undergrad How our Moon and Sun may affect Earth's equatorial bulge

Yesterday, 11:01 AM · Replies 3 · Today, 1:33 AM

Replies: 3

Views: 263

Winch rope force to pull back a folding canopy

Friday, 7:08 AM · Replies 9 · Today, 1:13 AM

Replies: 9

Views: 396

Sticky

Space Stuff and Launch Info

Jul 17, 2016 · Replies 2K · Today, 1:04 AM

53

Replies: 2K

Views: 166K

What is alfalfa used for?

Nov 16, 2025 · Replies 19 · Today, 12:20 AM

Replies: 19

Views: 891

ChatGPT Examples, Good and Bad

Jan 4, 2023 · Replies 442 · Yesterday, 3:55 PM

15

Replies: 442

Views: 32K

Undergrad Why if net force=zero, moment at any point is same?

Sunday, 12:52 PM · Replies 7 · Yesterday, 3:30 PM

Replies: 7

Views: 408

Graduate Confusion about the Moyal-Weyl twist

Yesterday, 4:09 AM · Replies 4 · Yesterday, 2:49 PM

Replies: 4

Views: 359

Magnitude of buoyant force in fluids of different densities

Thursday, 2:25 AM · Replies 17 · Yesterday, 2:45 PM

Replies: 17

Views: 758

Undergrad How to define a vector field?

Nov 25, 2025 · Replies 23 · Yesterday, 2:13 PM

Replies: 23

Views: 3K

Undergrad Derive the Lorentz transformation in Minkowski four-dimensional spacetime spacetime

Saturday, 10:11 PM · Replies 8 · Yesterday, 1:57 PM

Replies: 8

Views: 456

Sticky

Member and Mentor Appreciation Thread

Sunday, 9:34 AM · Replies 6 · Yesterday, 1:47 PM

Replies: 6

Views: 777

Graduate Universal quantum physics

Nov 20, 2025 · Replies 9 · Yesterday, 12:56 PM

Replies: 9

Views: 1K

How an agentic AI bot managed an office vending machine

Sunday, 4:48 PM · Replies 7 · Yesterday, 12:35 PM

Replies: 7

Views: 310

Optical Building a Raman spectrometer…

Sep 19, 2025 · Replies 52 · Yesterday, 10:45 AM

2

Replies: 52

Views: 6K

Engineering Rectifier Meter

Saturday, 9:02 AM · Replies 9 · Yesterday, 10:27 AM

Replies: 9

Views: 454

Sticky

Our Beautiful Universe - Photos and Videos

Feb 28, 2015 · Replies 2K · Yesterday, 9:26 AM

80

Replies: 2K

Views: 268K

Undergrad What upcoming experiments hold hope for physics BTSM?

Nov 12, 2023 · Replies 12 · Yesterday, 7:55 AM

Replies: 12

Views: 3K

Graduate Momentum density of silicon valence band using bandstructure

Dec 13, 2023 · Replies 2 · Yesterday, 7:52 AM

Replies: 2

Views: 3K

Undergrad Practical cosmic speed limit for macroscopic objects?

Sunday, 4:29 PM · Replies 4 · Yesterday, 7:08 AM

Replies: 4

Views: 281

Student of Astronomy and planetary science

Sunday, 4:39 PM · Replies 3 · Yesterday, 5:57 AM

Replies: 3

Views: 139

News Weird News Compilation

Jul 10, 2016 · Replies 2K · Yesterday, 4:44 AM

70

Replies: 2K

Views: 156K

What glass is best at resisting acids when dissolving?

Yesterday, 1:57 AM · Replies 1 · Yesterday, 2:09 AM

Replies: 1

Views: 239

Undergrad Relational event horizons?

Saturday, 6:50 PM · Replies 11 · Yesterday, 2:02 AM

Replies: 11

Views: 387

Collection of Science Jokes P2

Dec 11, 2015 · Replies 4K · Sunday, 10:03 PM

136

Replies: 4K

Views: 445K

Undergrad One does not “prove” the basic principles of Quantum Mechanics

Dec 1, 2025 · Replies 116 · Sunday, 6:23 PM

4

Replies: 116

Views: 5K

Undergrad Using the "triple point of water" to produce ice -- How does that work?

Sunday, 11:11 AM · Replies 2 · Sunday, 5:59 PM

Replies: 2

Views: 225

Undergrad Luminous Fast Blue Optical Transients (LFBOTs)

Sunday, 3:30 PM · Replies 0 · Sunday, 3:30 PM

Replies: 0

Views: 168

Graduate Is there some sort of transformation between Mandelstam parameters and Stokes parameters?

Sunday, 2:25 PM · Replies 0 · Sunday, 2:25 PM

Replies: 0

Views: 156

Undergrad How do I stretch a laser from a beam into a sheet?

Nov 20, 2025 · Replies 81 · Sunday, 10:31 AM

3

Replies: 81

Views: 3K

What causes the asymmetry in a symmetrically developing organism?

Saturday, 10:27 PM · Replies 5 · Sunday, 9:55 AM

Replies: 5

Views: 372

Poll

Physics Award

Dec 16, 2025 · Replies 1 · Sunday, 9:47 AM

Replies: 1

Views: 287

Poll

Engineering Award

Dec 16, 2025 · Replies 1 · Sunday, 9:47 AM

Replies: 1

Views: 198

Poll

Mathematics Award

Dec 16, 2025 · Replies 1 · Sunday, 9:46 AM

Replies: 1

Views: 262

Poll

Homework Helper Award

Dec 16, 2025 · Replies 1 · Sunday, 9:45 AM

Replies: 1

Views: 190

Poll

Hall of Legends Award

Dec 16, 2025 · Replies 1 · Sunday, 9:45 AM

Replies: 1

Views: 188

Poll

Academic Guidance Award

Dec 16, 2025 · Replies 1 · Sunday, 9:43 AM

Replies: 1

Views: 172

Poll

Community Spirit Award

Sunday, 8:43 AM · Replies 1 · Sunday, 9:42 AM

Replies: 1

Views: 183

Poll

Insights Author Award

Sunday, 8:56 AM · Replies 1 · Sunday, 9:41 AM

Replies: 1

Views: 154

Why Is Fan Suction/Intake So Weak Compared to Exhaust?

Thursday, 4:40 PM · Replies 10 · Sunday, 7:32 AM

Replies: 10

Views: 605

Bad Math Jokes

Jun 10, 2020 · Replies 413 · Sunday, 7:21 AM

14

Replies: 413

Views: 41K

Hydraulic Cylinder Held In Place Until Needed

Saturday, 7:49 PM · Replies 14 · Saturday, 11:35 PM

Replies: 14

Views: 253

Tidally-locked planets flipping around their axes

May 1, 2023 · Replies 28 · Saturday, 8:46 PM

Replies: 28

Views: 5K

High School Using battery energy to heat a battery…

Oct 21, 2025 · Replies 5 · Saturday, 7:39 PM

Replies: 5

Views: 575

Undergrad Questioning the timescape model

Friday, 11:20 AM · Replies 21 · Saturday, 6:21 PM

Replies: 21

Views: 564

Hi everyone

Saturday, 4:57 PM · Replies 1 · Saturday, 5:39 PM

Replies: 1

Views: 141

Undergrad Question of accuracy of galactic collision simulations

Oct 5, 2025 · Replies 10 · Saturday, 5:16 PM

Replies: 10

Views: 1K

Undergrad Before the Big Bang

Oct 26, 2025 · Replies 31 · Saturday, 10:50 AM

2

Replies: 31

Views: 1K

Random Photos

Oct 14, 2020 · Replies 3K · Saturday, 8:49 AM

114

Replies: 3K

Views: 163K

Graduate Stumped by a Lagrangian in Einstein's 1916 paper

Friday, 8:15 AM · Replies 3 · Saturday, 5:50 AM

Replies: 3

Views: 310

Random Thoughts 7

Jun 10, 2016 · Replies 2K · Saturday, 4:10 AM

65

Replies: 2K

Views: 61K

Undergrad Galactic collision and dark matter

Friday, 7:54 PM · Replies 1 · Saturday, 2:49 AM

Replies: 1

Views: 175

Correct statement about size of wire to produce larger extension

Dec 13, 2025 · Replies 17 · Saturday, 12:32 AM

Replies: 17

Views: 1K

High School Am I understanding the concept of proper frame of reference?

Dec 16, 2025 · Replies 33 · Friday, 9:55 PM

2

Replies: 33

Views: 1K

Air compressor pump HP requirement?

Thursday, 11:48 AM · Replies 9 · Friday, 6:24 PM

Replies: 9

Views: 294

High School Why is the constant speed of light so unique?

Dec 13, 2025 · Replies 19 · Friday, 1:49 PM

Replies: 19

Views: 1K

Undergrad Valid local explanation of Bell violations? (Pegg et al., 1999; 2008)

Dec 14, 2025 · Replies 37 · Friday, 11:21 AM

2

Replies: 37

Views: 2K

High School Is it a meteor or a meteorite when it makes moonfall?

Thursday, 8:23 PM · Replies 3 · Friday, 10:55 AM

Replies: 3

Views: 337

Pre-req for Ultrafast Optics? (Jackson or Zangwill for Electrodynamics?)

Thursday, 6:33 PM · Replies 4 · Friday, 10:52 AM

Replies: 4

Views: 645

How to route internet traffic via LAN port on a home router

Dec 14, 2025 · Replies 1 · Friday, 6:57 AM

Replies: 1

Views: 432

Sticky

Automotive Race car suspension Class

Jul 22, 2009 · Replies 2K · Friday, 4:29 AM

60

Replies: 2K

Views: 851K

Graduate Hypothesis testing: Defining H0, HA hypotheses so that ( H_A)_A' makes sense

Dec 16, 2025 · Replies 4 · Thursday, 8:13 PM

Replies: 4

Views: 601

High School Very high energy photons in space

Thursday, 5:12 AM · Replies 3 · Thursday, 5:16 PM

Replies: 3

Views: 565

Why Are You Still Here? A Curious Question

Nov 25, 2025 · Replies 19 · Thursday, 5:11 PM

Replies: 19

Views: 1K

High School Thought Experiment on Charge Carriers and Electrical Conduction

Wednesday, 12:33 AM · Replies 3 · Thursday, 3:06 PM

Replies: 3

Views: 298

The Secrets of Prof. Verschure's Rosetta Stones

Jul 28, 2023 · Replies 137 · Thursday, 12:04 PM

5

Replies: 137

Views: 28K

Programs Physics Masters at undergrad school before PhD?

Apr 15, 2025 · Replies 17 · Thursday, 9:44 AM

Replies: 17

Views: 2K

Graduate Alternative model for counterfactual definiteness in Bohm-like EPR

Wednesday, 8:18 AM · Replies 4 · Thursday, 9:34 AM

Replies: 4

Views: 431

Extremely Weird Music

Nov 4, 2025 · Replies 25 · Thursday, 8:34 AM

Replies: 25

Views: 1K

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