Hacker News: musgravepeter

New comment by musgravepeter in "Everyone is capable of, and can benefit from, mathematical thinking"

musgravepeter — Thu, 21 Nov 2024 14:43:28 +0000

New comment by musgravepeter in "Gravity's Eastern Voyage"

musgravepeter — Fri, 08 Nov 2024 17:33:08 +0000

https://royalsocietypublishing.org/doi/epdf/10.1098/rsnr.202...

New comment by musgravepeter in "Orbital Mechanics"

musgravepeter — Sun, 30 Apr 2023 16:09:58 +0000

Both these books are on my book shelf and are very good. Bate et. al. especially since it is a Dover book and very affordable.

The book that is always on my DESK is "Fundamentals of Astrodynamics and Applications" by Vallado. There is also a website with code from the book for Hohmann and Lambert transfers among other things. This has been indispensable in creating my Unity Asset "Gravity Engine".

New comment by musgravepeter in "Apollo 13 in Real Time"

musgravepeter — Sat, 15 Apr 2023 16:38:27 +0000

Take a look at https://store.steampowered.com/app/882140/Reentry__An_Orbita...

New comment by musgravepeter in "Gödel's solution to Einstein's field equations (2021)"

musgravepeter — Tue, 31 Jan 2023 17:33:42 +0000

The article mentions "few known exact solutions". There are actually quite a number. Most are from after 1950.

Cambridge University Press has two good books: Exact Spacetimes in Einstein's General Relativity (Griffith & Podolsky) - good readable (if you speak GR) account of the more common solutions Exact Solutions of Einstein's Feild Equations (Stephani, Kramer, MacCallum, Hoenstelaers, Herlt) - encyclopedic, authoritative and mathematical. In my case an aspirational purchase

General-relativistic thin-shell Dyson mega-spheres

musgravepeter — Thu, 07 Jul 2022 10:45:28 +0000

Article URL: https://arxiv.org/abs/2207.02465

Comments URL: https://news.ycombinator.com/item?id=32012324

Points: 2

# Comments: 0

New comment by musgravepeter in "Lagrange points solved one of physics' biggest problems"

musgravepeter — Fri, 18 Mar 2022 14:06:45 +0000

L4 and L5 are stable when the smaller mass is less than about 0.0385 times the larger mass [1]. This means e.g. a typical binary star system would not have stable L4/L5 points. The reference [1] works through this in careful detail and is an excellent reference on this topic.

[1] Solar System Dynamics, Murray and Dermott, Cambridge University Press.

New comment by musgravepeter in "So you want to study mathematics"

musgravepeter — Mon, 07 Mar 2022 19:11:39 +0000

+1 for Artin's Algebra. I think is very under appreciated.

New comment by musgravepeter in "So you want to study mathematics"

musgravepeter — Mon, 07 Mar 2022 18:09:27 +0000

I've been on a Math journey since I retired a couple of years ago and I agree with all the books mentioned that I know and look forward to picking up some of the one I do not know. I agree baby Rudin is essential, but I find it tough going.

Some books I liked for self study because they have answers:

Introduction to Analysis, Mattock.

Elementary Differential Geometry, Pressley.

There is also recently Needham's Visual Differential Geometry and Forms, which is great.

Edit: I should also mention Topology without Tears (free, online, very good) https://www.topologywithouttears.net/

So you want to study mathematics

musgravepeter — Mon, 07 Mar 2022 18:05:37 +0000

Article URL: https://www.susanrigetti.com/math

Comments URL: https://news.ycombinator.com/item?id=30591177

Points: 604

# Comments: 359

New comment by musgravepeter in "What is the inverse of a vector?"

musgravepeter — Wed, 03 Nov 2021 09:22:35 +0000

There is Geometric Algebra for Physicists by Doran and Lasenby (2003). It recasts mechanics, E&M up to gauge theories and GR into geometric algebra. I stalled out at mechanics but I've now taken it off the Tsundoku pile and may give it another chance.

New comment by musgravepeter in "Show HN: Relativity: A Modern Primer"

musgravepeter — Sun, 05 Sep 2021 10:15:33 +0000

I had a quick look and this seems like a solid, concise intro to GR.

The article https://people.carleton.edu/~nchriste/PTO000041.pdf gives an overview of the ways and books to learn GR. It does not cover some more recent intro books.

If you like "physics first" then I am a big fan of Hartle's book.

New comment by musgravepeter in "Ask HN: Technical Summer Reading List"

musgravepeter — Fri, 25 Jun 2021 12:16:22 +0000

Snap. I am also a physicist trying to learn math. In my case it's:

- Introduction to Analysis (Mattuck)

- Elementary Differential Geometry (Pressley)

both chosen because they have solutions in the book, which I find important for self-study.

Also just got (hot off the presses)

Visual Differential Geometry and Forms (Needham)

Looks fantastic!

Topology is next on the list...

New comment by musgravepeter in "First nuclear detonation created ‘impossible’ quasicrystals"

musgravepeter — Tue, 18 May 2021 09:14:50 +0000

Steinhardt's book "The second kind of impossible" describes his involvement with quasi-crystals. It's very worthwhile.

New comment by musgravepeter in "So You Want to Learn Physics, Second Edition"

musgravepeter — Thu, 22 Apr 2021 12:14:24 +0000

Really looking forward to the "So you want to learn math" list!

New comment by musgravepeter in "The Nobel Prize in Physics 2020"

musgravepeter — Tue, 06 Oct 2020 12:44:39 +0000

Penrose's contribution is reviewed in https://arxiv.org/abs/1410.5226

New comment by musgravepeter in "Astronomers find 'missing matter', solving decades-long mystery of outer space"

musgravepeter — Thu, 28 May 2020 13:05:24 +0000

"The discovery still leaves much of the universe undetected. About 85 per cent of its matter is thought to be "dark matter" — that which is undetectable using ordinary methods."

If I understand the abstract, it reports finding "Ωb=0.051+0.021−0.025h−170 (95 per cent confidence; h70 = H0/(70 km s−1 Mpc−1) " which I think means 5% of the total (mass+dark matter+dark energy), since cosmology assumes Omega total = 1.0

EinsteinPy: A Community Python Package for General Relativity

musgravepeter — Mon, 25 May 2020 13:55:28 +0000

Article URL: https://arxiv.org/abs/2005.11288

Comments URL: https://news.ycombinator.com/item?id=23301136

Points: 2

# Comments: 0

New comment by musgravepeter in "Apollo 11 50th Anniversary"

musgravepeter — Tue, 16 Jul 2019 13:21:46 +0000

The BBC podcast "13 minutes to the moon" is very worth-while.

New comment by musgravepeter in "Must-Read Books About the Moon"

musgravepeter — Mon, 01 Jul 2019 09:23:38 +0000

I am enjoying "The Moon, A history for the future" by Oliver Morton.