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

In summary, the conversation consists of various discussions about documentaries, the acquisition of National Geographic by Fox, a funny manual translation, cutting sandwiches, a question about the proof of the infinitude of primes, and a realization about the similarity between PF and PDG symbols. The conversation also touches on multitasking and the uniqueness of the number two as a prime number.
  • #5,041
He was the shortest tall guy. He was tall for his height.The other one was the world's tallest dwarf.
 
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  • #5,042
fresh_42 said:
We say "ur-" for great, and grandfather is the same "groß-vater". Thus you can have a great (großartig) ururururururururururururururururgroßvater. And it's shorter :wink: And even shorter if you replace grandfather by "opa".

Isn't Uropa a moon of Jupiter?
 
  • #5,043
BillTre said:
Isn't Uropa a moon of Jupiter?
I know where he is buried. If this is a moon of Jupiter we're in serious trouble!
 
  • #5,044
BillTre said:
Isn't Uropa a moon of Jupiter?
My pa? Not quite.
 
  • #5,045
I often get access to the bathroom ASAP when I head there at Starbucks. Strangely I had to wait each of the 3 times I tried today. I study , do my own small-scale ML for those who take long. My profile so far: Those dressed with brand-name clothes/ sun glasses. I have a theory but just speculation.
 
  • #5,046
fresh_42 said:
in was sugarfree.
..., which shall be read, "Artificial Sweetener Added" in the USA, and if you have my taste-buds, that means, "Tastes Like Gasoline, (do NOT buy)."
 
  • #5,047
Bystander said:
..., which shall be read, "Artificial Sweetener Added" in the USA, and if you have my taste-buds, that means, "Tastes Like Gasoline, (do NOT buy)."
I don't buy juices or soft drinks with artificial sweetener. Either I drink coke, aware of all the sugar, or I leave it. And in apple juice you do not need anything. Mother nature already sweetened it.
 
  • #5,048
fresh_42 said:
Mother nature already sweetened it.

Actually, selective agricultural breeding.
No natural apples were likely used.
 
  • #5,049
BillTre said:
Actually, selective agricultural breeding.
No natural apples were likely used.
After approximately 5,000 years and a journey around the globe, there are probably no "natural" apples left anywhere.
 
  • #5,050
The ESTA Paradoxon:

I just recognized that it is impossible for me to enter the US. They require a so called ESTA application. And here is why I cannot apply for a permission:
If I lie on the form, I will commit a crime and the application will be denied.
If I tell the truth, then the form does not accept my telephone number. It is too short and the US says it is invalid.

Next time I receive a call from the US I have to tell them that they dialed an invalid number ...

McCOY: The bureaucratic mentality is the only constant in the universe.
 
  • #5,054
Got my MSc. Next up, PhD. Abstract nonsense and semigroup theory o_O
 
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  • #5,055
nuuskur said:
Got my MSc. Next up, PhD. Abstract nonsense and semigroup theory o_O
Semigroups play a role in automaton theory and encryption theory as far as I remember, so abstract nonsense is relative.
 
  • #5,056
nuuskur said:
Got my MSc.
Congrats!
nuuskur said:
Next up, PhD. Abstract nonsense and semigroup theory o_O
Semigroup theory is only half as difficult as group theory, right? :wink:
 
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  • #5,057
Ibix said:
Congrats!

Semigroup theory is only half as difficult as group theory, right? :wink:
You mean that simple halfgroups are semisimple?
 
  • #5,058
fresh_42 said:
You mean that simple halfgroups are semisimple?
Sounds completely plausible to me...
 
  • #5,059
nuuskur said:
Abstract nonsense and semigroup theory o_O
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.
 
  • #5,060
strangerep said:
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).
 
  • #5,061
strangerep said:
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.
 
  • #5,062
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.
 
  • #5,063
fresh_42 said:
strangerep said:
[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. :headbang:
 
  • #5,064
strangerep said:
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.
 
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  • #5,065
fresh_42 said:
[...] 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.
 
  • #5,066
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.
 
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  • #5,067
France set a new record yesterday: 114.5 °F
 
  • #5,069
Looks a bit like the original Star Trek set, only with fewer colors and bigger.
 
  • #5,070
fresh_42 said:
making a lot of [insert]whining[/insert]noise.
 
  • #5,071
skyshrimp said:
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.
 
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  • #5,072
Something is wrong with me. I want to willingly learn about Galois theory mid-summer o_O
 
  • #5,073
nuuskur said:
Something is wrong with me. I want to willingly learn about Galois theory mid-summer o_O
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.
 
  • #5,074
fresh_42 said:
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.
 
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  • #5,075
Artin wrote a nice little book about it - old fashioned, i.e. pre-Bourbaki.
 

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