# Search results

1. ### "Fatal" mistake for flat earther

Hagar or Eratosthenes, that is here the question. It's tempting to feel a kind of joy, but on the other hand: some human being died completely without any sense. Guess the Darwin award this year will be his. What's really sad is, that Thales of Milet said it 2,600 years ago, and...
2. ### About the protein shape of covid-19

Italy is in the news, but the other European countries are affected, too. And they said it's now on all continents. (I guess they have forgotten to mention antarctica as exception, but who knows.) On Teneriffa is an entire hotel with 1,000 people under quarantine. Hardly. covid-19 basically...
3. ### Challenge Math Challenge - February 2020

I guess it's time to give both of you - @suremarc and @Antarres - the credit for solving the problem, since you both have had a correct strategy. Since this problem - Lemma of Babuška-Lax-Milgram - is a bit confusing, I'll add my proof. There was nothing wrong with either of yours, but for all...

5. ### Challenge Math Challenge - February 2020

I'm a bit skeptical about your use of duality. E.g. why is $\operatorname{im}B_1 =\mathcal{H}\,?$ Didn't you use $\mathcal{H}=\left(\mathcal{H}^*\right)^*$ with $\beta$ instead of the inner product? In other words: why does $B_1$ land in the space you claim it does? You have only added...
6. ### Random Thoughts part 6

But that's an order, not a question. The question would be: "Would you consider to give me your lunch money or shall I beat you up?" in which case yes or no is still the only solution, depending on the fitness of whom has been asked.
7. ### Random Thoughts part 6

Í like questions with an OR. They are usually so easy to answer.
8. ### Today I learned

I'm not totally sure, but isn't there a massive lack of Lithium in the universe?
9. ### Today I learned

You should have bought a couch instead of a smell on fibers attached. :wink: Maybe someone thought people would expect this, as they do in new cars. Btw. new airplanes have this smell of new like cars, too.
10. ### Random Thoughts part 6

$3 \nmid 28$ Blame the Babylonians and the Semitics. But there is a solution for you. Since you cannot return to the days when moon orbited earth faster, maybe you can wait until it is far enough that it takes $30$ days. Then you can introduce a week of $6$ days.
11. ### I Group Theory sub algebra of unitary group of U(6) group.

I already told you in post #2.
12. ### Learning physics from scratch

So have a look at the books on the RICE university site. You can download them as pdf and look into it! Just try and find out whether they are o.k. for you, too difficult or too easy. Whatever, it's for free.
13. ### I Group Theory sub algebra of unitary group of U(6) group.

Sorry, I do not download what I don't trust. If you want to type it instead, see https://www.physicsforums.com/help/latexhelp/ And I bet there are more than three subgroups in $U(6)$.
14. ### Learning physics from scratch

I don't know books in English at this level. I often cite https://openstax.org/subjects because they are free and can help to get started, and to find out what has to be learnt. However, there are better ones. Have you looked into our...

30. ### Challenge Math Challenge - February 2020

It does no harm to give an elementary proof.