What is the newest installment of 'Random Thoughts' on Physics Forums?

[Borg]

Did you knock three times?
https://www.thedibb.co.uk/forums/showthread.php?t=1102025

 

[cosmik debris]

Did you knock three times?
https://www.thedibb.co.uk/forums/showthread.php?t=1102025

Perhaps he is too short to reach the ceiling?

Cheers

 

[fresh_42]

Did you knock three times?
https://www.thedibb.co.uk/forums/showthread.php?t=1102025

I guess there is more than one good reasons to save the $14. Canada is funnier.

 

[nuuskur]

Got my MSc. Next up, PhD. Abstract nonsense and semigroup theory

 

[fresh_42]

Got my MSc. Next up, PhD. Abstract nonsense and semigroup theory

Semigroups play a role in automaton theory and encryption theory as far as I remember, so abstract nonsense is relative.

 

[Ibix]

Got my MSc.

Congrats!

Next up, PhD. Abstract nonsense and semigroup theory

Semigroup theory is only half as difficult as group theory, right?

 

[fresh_42]

Congrats!

Semigroup theory is only half as difficult as group theory, right?

You mean that simple halfgroups are semisimple?

 

[Ibix]

You mean that simple halfgroups are semisimple?

Sounds completely plausible to me...

 

[strangerep]

Abstract nonsense and semigroup theory

What types of semigroups? Have you formulated a well-defined PhD question yet?

I'm just curious because I've been trying to use Lie semigroups (actually Lie monoids) in some research, but had difficulty finding useful literature.

 

[nuuskur]

What types of semigroups? Have you formulated a well-defined PhD question yet?

I'm just curious because I've been trying to use Lie semigroups (actually Lie monoids) in some research, but had difficulty finding useful literature.

I confess, there is little literature known to me, as well, when it comes to recent developments in the theory.

In short, the goals for the PhD work is to generalise a description of Morita equivalence to factorisable semigroups (S=SS). This is quite a recent problem, starting early 90s and some remarkable advances occurring only ten years ago for semigroups with local units (a significantly smaller subclass than factorisables).

 

[fresh_42]

I'm just curious because I've been trying to use Lie semigroups (actually Lie monoids) in some research, but had difficulty finding useful literature.

Do you get a reasonable structure on the tangent spaces? I mean, you basically drop the minus sign in the commutator, don't you? And the detour to tangent spaces is the basic tool in Lie theory.

 

[skyshrimp]

This question belongs here as I've been drinking lots of cold beer (brain fart). Explain your take on it like I'm 6 years old. Just a random thought in random thoughts.

If the James Webb Telescope is being placed so far out that it can't ever be serviced, what's stopping it from getting damaged by high speed space debris? IIRC, Hubble has 'bullet holes' from high speed debris. The JWT looks like it mainly relies on huge glass planes/lenses which I'd of thought wouldn't last long with said random bombardment.

I'm actually worried that it's launch might fail.

 

[strangerep]

[Lie semigroups...]

Do you get a reasonable structure on the tangent spaces? I mean, you basically drop the minus sign in the commutator, don't you? [...]

That's not what I'm doing. I basically have 2 time-asymmetric Poincare-like algebras, acting on a double cone (in spacetime) with vertex removed. I.e., recall the null double cone in relativity, on a manifold locally Minkowskian. Then imagine different representations of a Poincare-like algebra acting on the forward and backward nappes of the double cone, such that in the forward (resp. backward) only forward (resp. backward) time translations are allowed.

So, at every point of the base manifold, my "tangent spaces" are this type of double cone, instead of a Minkowski space.

It's doing my head in for several years now.

 

[fresh_42]

I basically have 2 time-asymmetric Poincare-like algebras, acting on a double cone (in spacetime) with vertex removed.

Do you have a multiplication table for it? What makes them "like"? And can we continue in LA? Ooops, I meant the linear algebra forum, not LA (Ca).

I am asking because I am interested in the Poincaré algebra from another point of view.

 

[strangerep]

[...] can we continue in LA [forum]?

I can't say much more on the public PF forums, since it's unpublished.

I'll PM you later today.

 

[fresh_42]

The leaf blower is a symbol of our time:
It shifts a problem from one place to another without solving it, and making a lot of noise.

 

[fresh_42]

France set a new record yesterday: 114.5 °F

 

[DennisN]

NASA has restored the Apollo Mission Control. There are very nice high resolution photos in this article:

NASA’s restored Apollo Mission Control is a slice of ’60s life, frozen in amber (Ars Technica)
http://arstechnica.com/science/2019...wly-restored-historic-apollo-mission-control/

 

[fresh_42]

Looks a bit like the original Star Trek set, only with fewer colors and bigger.

 

[Bystander]

making a lot of [insert]whining[/insert]noise.

 

[pinball1970]

This question belongs here as I've been drinking lots of cold beer (brain fart). Explain your take on it like I'm 6 years old. Just a random thought in random thoughts.

If the James Webb Telescope is being placed so far out that it can't ever be serviced, what's stopping it from getting damaged by high speed space debris? IIRC, Hubble has 'bullet holes' from high speed debris. The JWT looks like it mainly relies on huge glass planes/lenses which I'd of thought wouldn't last long with said random bombardment.

I'm actually worried that it's launch might fail.

It will take hits every year but they will be mainly microscopic and damages will take time to accumulate.
March 2021 is the last date for launch I read.
If they get to the stage where micro damage to the mirrors is about to be a possibility then the project will have been successful.
Fingers crossed.

 

[nuuskur]

Something is wrong with me. I want to willingly learn about Galois theory mid-summer

 

[fresh_42]

Something is wrong with me. I want to willingly learn about Galois theory mid-summer

Better to learn what Galois thought, than to learn what he did!

Galois theory is one of the most beautiful encapsulated theories in mathematics. And that it solves all three classical problems once and for all is a nice application.

 

[Ibix]

Better to learn what Galois thought, than to learn what he did!

It turns out that duality is a useful mathematical concept; duelity less so.

 

[fresh_42]

Artin wrote a nice little book about it - old fashioned, i.e. pre-Bourbaki.

 

[fresh_42]

It turns out that duality is a useful mathematical concept; duelity less so.

In a way it is both in this case, isn't it?

 

[Ibix]

In a way it is both in this case, isn't it?

I don't follow. Are you suggesting that duels are the duals of duals?

 

[Ibix]

...or that duals and duels duelled for Galois' attention?

 

[fresh_42]

I don't follow. Are you suggesting that duels are the duals of duals?

No, that towers of groups corresponding one-to-one to towers of fields is a form of duality.

 

[Ibix]

No, that towers of groups corresponding one-to-one to towers of fields is a form of duality.

I don't know enough about Galois to appreciate that, I'm afraid. Perhaps @nuuskur will run a study group...

 

[nuuskur]

Why can't philosophy be concise? Or is it possible to make it concise, but it's avoided intentionally? Is there too much effort involved in precision? What is there to gain from obscurity apart from stringing a lot of fancy sounding words together and trying to make it look like it's profound or complex?
*Initiate pulling out hair in 3 ..2 ..1 *

What is the group complexity of a human mind, provided it could be modeled as an automaton? Is there a non-trivial lower bound? Does every philosophy major's mind contain an isomorphic copy of a certain subautomaton?

 

[fresh_42]

Why can't philosophy be concise? Or is it possible to make it concise, but it's avoided intentionally?

This is unfair towards philosophy. E.g. Kant was very interested in precision, which is why he is so hard to read. Wittgenstein investigated the language itself as major transport of information.

We all know about the ambiguity of language which is why we use formulas. Even something as simple as a quantification is immensely difficult in language, so that we use $\forall \, , \,\exists$ if in doubt. Compare the many threads here and the number of posts related to problem description instead of problem solution! These are indicators that verbal language is immanent ambiguous. Hence philosophers have to deal with a tool that is all but perfect. This does not mean they do not try, it means that they carry a handicap they cannot get rid of.

 

[pinball1970]

This is unfair towards philosophy. E.g. Kant was very interested in precision, which is why he is so hard to read. Wittgenstein investigated the language itself as major transport of information.

We all know about the ambiguity of language which is why we use formulas. Even something as simple as a quantification is immensely difficult in language, so that we use $\forall \, , \,\exists$ if in doubt. Compare the many threads here and the number of posts related to problem description instead of problem solution! These are indicators that verbal language is immanent ambiguous. Hence philosophers have to deal with a tool that is all but perfect. This does not mean they do not try, it means that they carry a handicap they cannot get rid of.

I would say 'inherently' ambiguous. It flows better.

 

[nuuskur]

Finally got time to finally play through Witcher 3. I'm MIA for a couple of days

 

[WWGD]

Why can't philosophy be concise? Or is it possible to make it concise, but it's avoided intentionally? Is there too much effort involved in precision? What is there to gain from obscurity apart from stringing a lot of fancy sounding words together and trying to make it look like it's profound or complex?
*Initiate pulling out hair in 3 ..2 ..1 *

What is the group complexity of a human mind, provided it could be modeled as an automaton? Is there a non-trivial lower bound? Does every philosophy major's mind contain an isomorphic copy of a certain subautomaton?

Once you can make something clear and precises , point the basic concepts, it stops being part of the realm of Philosophy, at least as I understand it. Philosophy deals in a relatively open-ended way about the topics it addresses. Notice , e.g., Psychology was once part of Philosophy. Once main assumptions, results , schemas were made precise, it started becoming something other than Philosophy. Unless you're referring to the study of people named 'Phil' ( the other Philosophy) , that is my take.

 

[WWGD]

More parsing confusions:

"What a Bautism" ? Actually Whataboutism, a relatively new word.

Newscaster: " Until Next time I'm Erika" * : Until Next time America

*And then my shouting, next I saw him in the street, in-between shows: " Hello Erika!"

" Give me Chicken over Ice" : Give me Chicken over Rice. Note I am not saying that I prefer Chicken to Rice ( Nor Ice) nor anything about Condoleeza Rice ( The best brand of rice!). Do you like Condoleeza rice? No, I prefer Uncle Ben's.

 

[WWGD]

Sorry for my mental Diarrhea. mail.com just deleted 98% of my mails for no reason I can gather. I checked the mail settings and for each folder except for Spam, where settings are to delete after 30 days, the settings are to store mail indefinitely.

 

[nuuskur]

my number theory has gone down the drain, I can't even prove something elementary like $[a,(b,c)] = ([a,b],[a,c])$

 

[fresh_42]

my number theory has gone down the drain, I can't even prove something elementary like $[a,(b,c)] = ([a,b],[a,c])$

The elegant way by ideals or by foot via prime decomposition? In any case, I guess it is simply too hot.

 

[nuuskur]

via prime decomposition

If I calculated correctly, we'd need to justify
<br /> \max \{k_j, \min \{l_j,r_j\}\} = \min \{\max\{k_j,l_j\},\max \{k_j,r_j\}\}<br />
where a = \prod _{j=1}^n p_j^{k_j},\ b = \prod _{j=1}^n p_j^{l_j}, \ c = \prod _{j=1}^n p_j^{r_j}. I've no idea how to analyse such a statement other than case by case :/ Looks like some kind of distributivity. Need to dust off my lattice theory

It is hot .. and humid, that's worse.

 

[fresh_42]

I am each year newly amazed and fascinated:

75,000 metal rocker on some farmer fields of a northern 2,000 people village, and it looks as if Scandinavia has more hard rocker than citizens: Swedish, Danish, Finnish and Dutch bands. They even have a beer pipeline!

I miss Lemmy.

 

[pinball1970]

I am each year newly amazed and fascinated:

75,000 metal rocker on some farmer fields of a northern 2,000 people village, and it looks as if Scandinavia has more hard rocker than citizens: Swedish, Danish, Finnish and Dutch bands. They even have a beer pipeline!

I miss Lemmy.

That is a festival I could get on board with.

 

[fresh_42]

That is a festival I could get on board with.

Yes. It is a bit like alien meets bumpkin, but both love it. Harder, faster, louder, but the local firefighters band with trumpets and tubas opens the festival. They broadcast it on tv right now and I think there is also a livestream. I thought "Frisians among themselves" as I saw all those bands from North Sea countries. And yes, Lemmy was there eight times, so the North Sea country UK also contributed.

I think this entire thing is a bit British: understatement, international, rural, beer, beer, beer, and making friends with everybody. No, wonder, England is close and the people around the coastlines are rather similar.

 

[pinball1970]

Yes. It is a bit like alien meets bumpkin, but both love it. Harder, faster, louder, but the local firefighters band with trumpets and tubas opens the festival. They broadcast it on tv right now and I think there is also a livestream. I thought "Frisians among themselves" as I saw all those bands from North Sea countries. And yes, Lemmy was there eight times, so the North Sea country UK also contributed.

Lemmy was a legend, he didn't stop.
It sounds great, the sound out doors tends to be hit and miss but I love that vibe.
Not sure I could handle all day drinking and crashing out in a tent.
Certainly not 2 or 3 days.

 

[fresh_42]

Lemmy was a legend, he didn't stop.

He is one of those persons to whom the following quote fits:
"Joe [Cocker] will sing Madonna from stage even with half a liver! "
(A fellow student once said at the mensa table long ago)
Guess, Keith belongs in that club as well.

 

[fresh_42]

Not sure I could handle all day drinking and crashing out in a tent.
Certainly not 2 or 3 days.

Me neither ... meanwhile.
But the atmosphere looks great, especially at night.

 

[pinball1970]

Me neither ... meanwhile.
But the atmosphere looks great, especially at night.

I'll check it out for sure

 

[fresh_42]

I'll check it out for sure

There's a youtube clip from 2006 (75 min.):

 

[Astronuc]

Some clever insight:

Knowledge is knowing a tomato is a fruit,
Wisdom is not putting it in a fruit salad, and
Philosophy is wondering if that means ketchup/catsup is a smoothie.

 

[Klystron]

my number theory has gone down the drain, I can't even prove something elementary like $[a,(b,c)] = ([a,b],[a,c])$

I must be a maths dilettante. I see distribution but leave proofs to others. How trusting.

If I calculated correctly, we'd need to justify
<br /> \max \{k_j, \min \{l_j,r_j\}\} = \min \{\max\{k_j,l_j\},\max \{k_j,r_j\}\}<br />
where a = \prod _{j=1}^n p_j^{k_j},\ b = \prod _{j=1}^n p_j^{l_j}, \ c = \prod _{j=1}^n p_j^{r_j}. I've no idea how to analyse such a statement other than case by case :/ Looks like some kind of distributivity. Need to dust off my lattice theory

It is hot .. and humid, that's worse.

Appears to me to be good old min-max theorem. But dilettantes do tend to over simplify.
To day I shall contemplate how best to dust a lattice.