hansen

6 ms·

1.
by hansen 5y ago
To be a bit pedantic: the identification of tensors with multilinear forms requires finite dimensions (or reflexive topological spaces).
2.
by hansen 7y ago
Physicists and philosophers of science give those terms different meanings. E.g. what a philosopher of science would call a theory is called model by physicists. What physicists call a theory is more a broad framework in which more
3.
by hansen 7y ago
Spacetime is extremely stiff or equivalently gravity extremely weak. Only these extreme events result in detectable gravitational waves.
4.
by hansen 7y ago
I doubt there are many users out there who care if someones analytics stuff breaks.
5.
by hansen 7y ago
The standard (but rather heavy and difficult) is Abraham, Marsden: Foundations of Mechanics More gentle is Vladimir Arnold: Mathematical Methods of Classical Mechanics
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by hansen 7y ago
I don’t think the typical “change of variables” definition is bad. You take the derivative of L along the fiber of the tangent bundle. If the derivative is non-singular it defines an isomorphism in each point of the tangent space with the
7.
by hansen 7y ago
Mathematicians messed up here… A manifold with boundary is not a manifold. But a manifold is a manifold with boundary (the empty set).
8.
by hansen 8y ago
Gravitational waves are disturbances in a background spacetime, i.e. you linearize the Einstein equations around a given solution. The analogy is less bad as one might initially think
9.
by hansen 8y ago
I always thought it's more about caching
10.
by hansen 8y ago
The problems in the classical theory are easily understood. The charge and current densities of point particles are not smooth functions but distributions (think of the Dirac δ-“function”). If they act as the sources of the EM field the E
11.
by hansen 8y ago
> Given the trajectories of charges it will tell you what the electromagnetic field will be, and given the electromagnetic field it will tell you how charges will move. Unfortunately, these two parts of the theory seem to be incompatible
12.
by hansen 8y ago
And all those Emacs jokes don't work anymore
13.
The CumEx-Files – How Europe's taxpayers have been swindled of €55B(cumex-files.com)
357 points by hansen 8y ago|105 comments
14.
by hansen 8y ago
If you want Cᵏ to be a normed space you do |f| = ∑ᵢ₌₀ᵏ sup|f⁽ⁱ⁾|. On open domains you can also use the topology that forces uniform convergence on all compact subsets. But this will only give you a metric space, no Banach space (but you’ll
15.
by hansen 8y ago
> there is enough experimental evidence that is anomalous to the theories Huh? I have more the impression that Λ-CDM & SM are working just too damn good. I’m not aware of any observation that hints that we need something completely
16.
by hansen 8y ago
> For example, ask a lay person about BB and they will tell you it's an explosion, in the classical sense Give her Weinberg’s book to read and she’ll come to a different conclusion. Of course those books won’t give you a deep under
17.
by hansen 8y ago
All our accepted model of nature assume that in some sense time exists. But in general relativity it doesn’t make much sense to speak of a single event. In the same way it doesn’t make much sense to speak of a single point in the euclidea
18.
by hansen 8y ago
Yeah, science isn’t about being useful and relevant in day to day life. It’s an important part of human culture and scientist should at least try to communicate their findings to general public (which is paying for it!). I partially agree
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by hansen 8y ago
> Sure, but regular quantum mechanics does the same thing. It's > under-constrained and allows for too many possibilities. No it doesn’t. There are a few good guiding principles that make it possible to build models that turn o
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by hansen 8y ago
Because the author is a well respected scientist and quite talented science writer & journalist. https://en.wikipedia.org/wiki/Ethan_Siegel
21.
by hansen 8y ago
> their [EU] first ruling is that basically every website is not > allowed to use ads to pay itself. Of course they won’t. This is absurd.
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by hansen 8y ago
They might be stupid but almost every website is even more stupid. Almost none offers a way out of spying.
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by hansen 8y ago
> The GDPR requires users to be able to say no Even better, it requires the use to say “yes”.
24.
by hansen 8y ago
> If it's anything like the cookie consent, It won’t. It will just replace the common “no one reads but clicks” TOS. And the user can change her mind anytime she wants. > The amount of "no clue what this is" among non
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by hansen 8y ago
> Seems to come down to having to protect users from their own lack > of understanding. I had the impression that this is rather clearly regulated by the GDPR. A user has to consent to each use of her data. And you have to explain
26.
by hansen 8y ago
The startup could just respect their users privacy. It's only a matter of decency. Most people don't have much problems with it.
27.
by hansen 8y ago
In Germany ads must be distinguishable from other content. If a human can spot the difference it shouldn’t be too hard to automate that process.
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by hansen 8y ago
You shouldn't use the term enhancing user experience . It’s a synonym for doing something against the interest of the user.
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by hansen 8y ago
> You can get close with a built in browser setting. And you can still keep cookies from specific sites by defining an exception. They should better document this feature. For me it would be a good default behavior. There aren’t that
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by hansen 8y ago
> enhance the user experience Sorry, but this made me laugh. > whats the alternative to 3rd party cookies? Don't use a 3rd party service.

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