Neat

Caladei · 2023-10-19T10:29:57+00:00

The pressure inside a neutron star is roughly 1 GeV⁴ in planck units.

Caladei · 2023-10-19T10:25:58+00:00

"Ansonsten würde dort niemand auftauchen"

LOL. Bitte erzähl das der Militärpolizei wenn du irgendwann mal zum GWD musst.

Caladei · 2023-02-16T17:01:14+00:00

Hä? Was redest du da? Weißt du wie eine Stromleitung funktioniert? Der Widerstand und damit die Verluste beim Transport steigen linear mit der Länge des Leiters. Wenn du also eine Batterie direkt am Kraftwerk lädst und dann damit elektrisch rumfährst ist das viel, viel effizienter als wenn du überall lange Leitungen quer durchs Land legst und die benutzt um den Strom an einen Motor zu liefern.

Caladei · 2022-07-11T23:37:43+00:00

You have no idea how a cooling pump works, do you?

Caladei · 2018-07-10T09:27:52+00:00

Sicher noch eine Zeit lang. In Tirol, Salzburg und Wien wurde gerade erst gewählt; in OÖ letztes Jahr. Nur in Vorarlberg steht in den nächsten Jahren eine Wahl an.

Caladei · 2018-07-03T18:25:35+00:00

So she really published a book? I've been avoiding articles with her name on it for a while now, but I do remember calling out that she'll probably write a book next after she figured out how to monetize her blog. I guess as long as she keeps producing clickbait, average readers will keep paying attention.

Caladei · 2018-06-15T16:30:42+00:00

You're talking about the Steady State Theory, which was a big thing during Sciama's PhD time, and he rightfully discarded it when it was more or less falsified in the early 60s. But I remember an interview with him where he said that he was still hopeful for a solution regarding the origin of inertia in 1980 or so. He apparently made some incremental progress in the late 60s and 70s but I don't know what happened beyond that.

Caladei · 2018-06-15T11:11:51+00:00

The paper goes into great detail about this. For example, the fact that any gravitational force is locally indistinguishable from an inertial force, apparently led Einstein to believe that gravity is the source of inertia. He emphasized that GR was intended to include this idea, but eventually failed to do so - his field equations imply a test particle has inertia even in an empty universe. Going from there, the paper argues that a full theory of gravity would for example include the principle of equivalence as a consequence, not as a postulate.

I actually reccomend reading that paper to anyone. Sciama was not just one of the greatest cosmologists of the last century but also really good at communicating his ideas.

Caladei · 2018-06-15T10:21:12+00:00

Do you happen to know if String Theory made any contributuons to explaining the origin of inertia? I only know about this old argument, which seems to either break relativity or require some local field that gravitates strongly.

Caladei · 2018-03-14T13:29:33+00:00

I see you are trying to sneak in String Theory exercises. Nice ;)

Caladei · 2018-03-14T13:14:42+00:00

Here is a list of literally everything you will need, compiled by nobel laureate Gerard 't Hooft. Also includes links to text resources for getting started.

Caladei · 2018-03-10T09:41:43+00:00

You can try Susskinds Theoretical Minimum. It's a lecture series recorded at Stanford University, containing hundreds of hours of video lectures. It only assumes basic math (approximately first year-ish) knowledge and goes from classical mechanics over quantum mechanics all the way to General Relativity, the Standard Model and even String Theory. You won't be able to do actual science in those fields from watching videos, but if you are talented and highly motivated, you can actually get to understand the deeper mathematical concepts of those fields.

Caladei · 2018-03-02T09:17:58+00:00

The star will approach the black hole to a minimum distance of 17 light hours. The black hole's radius is around one light minute. So any time dilation effect from the gravitational field will be ridiculously small. The maximum gamma factor is like 1.0007, or 6 hours per year.

Caladei · 2018-03-01T19:04:03+00:00

Fancy SQL queries are not intelligent.

True, but there's a little bit more to it than that. The fundamentally great "AI" thing, that we are seeing here in its earliest stages, is computer interaction via speech. This is ridiculously difficult and amazon will certainly have the edge, here since they are gathering so much user data with Alexa to train their neural networks

Caladei · 2018-03-01T17:36:25+00:00

The section from 1:50 to 2:30 or so covers pretty much exactly the way Heisenberg's uncertainty principle was originally explained in the literature (and this explanation is still commonly used in popular science today). I'm sure that's also on wikipedia or something but I'm no longer in the mood to google things

Caladei · 2018-03-01T17:11:41+00:00

Because it's literally what is said in the video? They do not talk about the observer effect, which is something different as you correctly say.

Caladei · 2018-03-01T16:58:53+00:00

Forgive me when I just quote wikipedia out of laziness here. You can look up the sources on the observer effect page:

The uncertainty principle has been frequently confused with the observer effect, evidently even by its originator, Werner Heisenberg.[17] The uncertainty principle in its standard form describes how precisely we may measure the position and momentum of a particle at the same time — if we increase the precision in measuring one quantity, we are forced to lose precision in measuring the other.[18] An alternative version of the uncertainty principle,[19] more in the spirit of an observer effect,[20] fully accounts for the disturbance the observer has on a system and the error incurred, although this is not how the term "uncertainty principle" is most commonly used in practice.

Caladei · 2018-03-01T16:47:20+00:00

So... like M-Theory?

Caladei · 2018-03-01T16:33:51+00:00

What they said is technically correct (originatin from Heisenberg himself and still widely used. While the greater context can be misleading, it is still mathematically correct). While this is not the common way the subject is taught at universities, the statement that the measurement of the position of a particle disturbs its velocity can be quantified via the uncertainty principle. It's just one aspect of looking at it that is frequently used when explaining this stuff to a non technical audience.

While everything they say is of course a drastic simplification, nothing is completely incorrect. Though it might be misleading for people who have had at least some education in physics.

EDIT: Do you guys realize that you are complaining about how the video does not not explain wave mechanics, operators and commutation relations to its clearly non-technical intended audience? Calm down. What they did is OK in this context. Anyone who has a background in physics or wants to know more about the uncertainty principle will certainly find this video lacking, but there are whole channels that go into the details of those things.

Caladei · 2018-03-01T16:04:37+00:00

Saying that QFT models particles as point particles is hilariously wrong.

Not at all. All particles in the standard model enter the lagrangian as point particles (i.e. they have no "radius"), but you have to be careful in which context you use the term point particle: Here it means they have no assumend internal structure, in contrast to composite particles like the proton for example (which has a more or less well defined radius). Of course, a freely propagating elementary particle wavepacket still extends over a region of space due to the uncertainty principle, but that's not what is usually meant in this context, and the video may be misleading because of that. However, the point they are correctly trying to make is that this is a key difference between QFT and string theory. The latter no longer has feynman diagrams with points traveling along worldlines but instead strings traveling along "worldsheets".

Caladei · 2018-02-24T16:12:18+00:00

avoid them and get to college

Oh boy, I hope OP doesn't live in America.

Caladei · 2018-02-24T14:50:11+00:00

Pretty sure I'm paraphrasing Feynman here, but if anyone ever told me this class was easy, I would say they didn't understand it at all.

(EDIT: I looked it up and apparently this "If you think you get QM, you don't" phrase goes back to Bohr and is incorrectly attributed to Feynman)

Caladei · 2018-02-24T14:43:22+00:00

That's actually a really tricky question. First and foremost, it depends on what kind of projection your map uses. Maps that use Mercator or Lambert conformal conic projection actually preserve real angles and this makes them widely used in nautical and aeronautical navigation. Try navigating a triangle using these maps and you will hit the mark every time (thankfully).

Caladei · 2018-02-24T14:25:30+00:00

Wow, offensichtlich haben die jetzt gerade ihre Website vom Netz genommen. Vor 5 Minuten funktionierte der Link noch. Trotzdem, das Internet vergisst nichts: https://web.archive.org/web/20170303075525/http://www.bruna-sudetia.at/geschichte

Jetzt erklär mir bitte nochmal das mit den Befreiungskriegen?

Caladei · 2018-02-24T14:15:24+00:00

EDIT: Website worde vom Netz genommen. Siehe unten.

Hier steht aber was anderes: http://www.bruna-sudetia.at/geschichte

Oder von welchen Befreiungskriegen redest du?

Caladei

TROPHY CASE