ohwilleke's latest activity
-
ohwilleke replied to the thread Undergrad Question of accuracy of galactic collision simulations.The reason that this particular example is so hard is not because it is, fundamentally, a huge many body problem, but because the... -
ohwilleke reacted to FactChecker's post in the thread Undergrad Question of accuracy of galactic collision simulations with
Like.
I spent my entire career in simulation (not this type). This strikes me as an exceedingly difficult subject to simulate. The numbers... -
ohwilleke replied to the thread Undergrad Question of accuracy of galactic collision simulations.One of the rather surprising observational facts about dark matter distributions in galaxies is that they show surprising similarities...
-
ohwilleke replied to the thread Undergrad Question of accuracy of galactic collision simulations.After giving it some more thought, the reason that I think that the simulation rather than the astronomy observations are the main...
-
ohwilleke replied to the thread Undergrad Question of accuracy of galactic collision simulations.This is definitely a possibility. When you are comparing simulations to astronomy observations, I focused on the issues with the...
-
ohwilleke replied to the thread Undergrad Question of accuracy of galactic collision simulations.Astronomy/cosmology simulations do two main things: 1. They rely on a set of assumptions about the physics involved, which are physics...
-
https://en.wikipedia.org/wiki/Yang_Chen-Ning ( photo from http://insti.physics.sunysb.edu/~yang/ )...
-
ohwilleke posted the thread Undergrad C.N. Yang dies at age 103 in High Energy, Nuclear, Particle Physics.Theoretical physicist C.N. Yang died at the age of 103 years on October 18, 2025. He is the Yang in Yang-Mills theory, which he and his...
-
ohwilleke reacted to pines-demon's post in the thread Asimov's Foundation: Am I the only one who likes the show more? with Like.
Oh boy I finally got to watch season 2. What a fabulous... mess. I can say that: I liked most of the fabricated new plots related to...
-
ohwilleke replied to the thread Undergrad Is Gravi-GUT a candidate theory of everything?.A gravi-GUT could be a TOE but wouldn't necessarily be, in the strict sense. A GUT is a unified theory of the three SM forces. A TOE...
-
ohwilleke reacted to PeroK's post in the thread Undergrad How Can Photons Be Massless Yet Have Energy According to Einstein's Equations? with Like.
The equation ##E = mc^2## only applies to a particle with mass. And, indeed, that's its energy only when it is at rest. The full...
-
ohwilleke reacted to Ibix's post in the thread Undergrad How Can Photons Be Massless Yet Have Energy According to Einstein's Equations? with Like.
That formula is only correct for stationary massive objects. The general formula is ##m^2c^4=E^2-p^2c^2##, from which you can see that...
-
ohwilleke reacted to jhonconnor's post in the thread Undergrad Why is there such a difference between the total cross-section data? (simulation vs. experiment) with Like.
Well, I found that it's due the contribution of other states. In other words, for energies below 1 MeV, ##^3\mathrm{S}_1## and...
-
ohwilleke replied to the thread High School Asteroid 2024 YR4 has a 1% risk of a multi-megaton impact in 2032 (now ruled out).Crude order of magnitude, back of napkin estimates are still probably good enough to rule out EMP as a serious risk of the proposal. I...
-
ohwilleke reacted to DaveC426913's post in the thread High School Asteroid 2024 YR4 has a 1% risk of a multi-megaton impact in 2032 (now ruled out) with
Informative.
I think EMPs radii are on the order of hundreds of miles - maybe thousands of miles - not tens of thousands of miles, let alone...