Pi bond Updated 2025-07-16
Galilean invariance Updated 2025-07-16
A law of physics is Galilean invariant if the same formula works both when you are standing still on land, or when you are on a boat moving at constant velocity.
For example, if we were describing the movement of a point particle, the exact same formulas that predict the evolution of must also predict , even though of course both of those will have different values.
It would be extremely unsatisfactory if the formulas of the laws of physics did not obey Galilean invariance. Especially if you remember that Earth is travelling extremelly fast relative to the Sun. If there was no such invariance, that would mean for example that the laws of physics would be different in other planets that are moving at different speeds. That would be a strong sign that our laws of physics are not complete.
Lorentz invariance generalizes Galilean invariance to also account for special relativity, in which a more complicated invariant that also takes into account different times observed in different inertial frames of reference is also taken into account. But the fundamental desire for the Lorentz invariance of the laws of physics remains the same.
Game AI research lab Updated 2025-07-16
The Quora question: www.quora.com/Are-there-any-PhD-programs-in-training-an-AI-system-to-play-computer-games-Like-the-work-DeepMind-do-combining-Reinforcement-Learning-with-Deep-Learning-so-the-AI-can-play-Atari-games
game-icons.net Updated 2025-07-16
Ciro Santilli used it for the 2D version of his Ciro's 2D reinforcement learning games.
Gamma ray Updated 2025-07-16
Their energy is very high compared example to more common radiation such as visible spectrum, and there is a neat reason for that: it's because the strong force that binds nuclei is strong so transitions lead to large energy changes.
A decay scheme such as Figure "caesium-137 decay scheme" illustrates well how gamma radiation happens as a byproduct of radioactive decay due to the existence of nuclear isomer.
Gamma rays are pretty cool as they give us insight into the energy levels/different configurations of the nucleus.
They have also been used as early sources of high energy particles for particle physics experiments before the development of particle accelerators, serving a similar purpose to cosmic rays in those early days.
But gamma rays they were more convenient in some cases because you could more easily manage them inside a laboratory rather than have to go climb some bloody mountain or a balloon.
The positron for example was first observed on cosmic rays, but better confirmed in gamma ray experiments by Carl David Anderson.
Gas chromatography Updated 2025-07-16
This technique is crazy! It allows to both:You actually see discrete peaks at different minute counts on the other end.
- separate gaseous mixtures
- identify gaseous compounds
It is based on how much the gas interacts with the column.
Detection is usually done burning the sample to ionize it when it comes out, and then you measure the current produced.
Gas chromatography by Quick Biochemistry Basics (2019)
Source. Gas chromatography etymology Updated 2025-07-16
Gauge symmetry Updated 2025-07-16
Lawrence Krauss explains Gauge symmetry by Joe Rogan (2017)
Source. While most of this is useless as you would expect from the channel, it does give one key idea: you can change charge locally, but things somehow still work out.
And this has something to do with the general intuition of special relativity that only local measures make much sense, as evidenced by Einstein synchronization.
Gay porn meme Updated 2025-07-16
Best ones:
- Change in your couch
- Put ketchup on fries
Sex-ratio imbalance in China Updated 2025-07-16
GDB Dashboard Updated 2025-07-16
Generalized Poincaré conjecture Updated 2025-07-16
There are two cases:
- (topological) manifolds
- differential manifolds
Questions: are all compact manifolds / differential manifolds homotopic / diffeomorphic to the sphere in that dimension?
- Original problem posed, for topological manifolds.AKA: classification of compact 3-manifolds. The result turned out to be even simpler than compact 2-manifolds: there is only one, and it is equal to the 3-sphere.
- for differential manifolds:Counter examples are called exotic spheres.Totally unpredictable count table:is an open problem, there could even be infinitely many. Again, why are things more complicated in lower dimensions??
The Oxford Solid State Basics Updated 2025-07-16
General relativity Updated 2025-07-16
Unifies both special relativity and gravity.
Not compatible with the Standard Model, and the 2020 unification attempts are called theory of everything.
One of the main motivations for it was likely having forces not be instantaneous, but rather mediated by field to maintain the principle of locality, just like electromagnetism did earlier.
Cool data embedded in the Bitcoin blockchain Len Sassaman tribute Updated 2025-07-16
Tribute to computer security researcher Len Sassaman, who killed himself on 2011-07-03, starting with an ASCII art portrait followed by text.
Because it comes so early in the blockchain, and because it is the first ASCII art on the blochain as far as we can see, and because is so well done, this is by far the most visible ASCII art of the Bitcoin blockchain.
Present at tx 930a2114cdaa86e1fac46d15c74e81c09eee1d4150ff9d48e76cb0697d8e1d72. It does not show well on Bitcoin Inscription Indexer however with rationale described at: github.com/cirosantilli/bitcoin-inscription-indexer/tree/3f53e152ec9bb0d070dbcb8f9249d92f89effa70#smart-newline-joining
But it can be seen at on bitcoinStrings.com at: bitcoinstrings.com/blk00003.txt.
Transaction: www.blockchain.com/btc/tx/930a2114cdaa86e1fac46d15c74e81c09eee1d4150ff9d48e76cb0697d8e1d72 from 2011-07-30, a few weeks after the suicide.
Discussion: bitcoin.stackexchange.com/questions/3370/in-which-block-was-len-sassaman-memorialised/101276#101276
Created by famous computer security researcher Dan Kaminsky and Travis Goodspeed, presumably this other security researcher, evidence:
- signature on the tribute
- the art is highlighted at Video 1. "Black OPS of TCP/IP by Dan Kaminsky (2011)", which happened very few days after the art was uploaded to the blockchain, thus making it exceedingly unlikely that someone else could have done it
"Bernanke" is a reference to Ben Bernanke, who was one of the economists in power in the US Government during the financial crisis of 2007-2008, and much criticized by some, as shown for example in the documentary Inside Job (2010). As hinted in the Genesis block message, the United States Government bailed out many big banks that were going to go bankrupt with taxpayer money, even though it was precisly those banks that had started the crisis through their reckless investment, thus violating principles of the free market and business accountability. This was one of the motivations for the creation Bitcoin, which could reduce government power over economic policy.
It is worth mentioning that there do exist some slightly earlier "artistic" inscriptions in the form Punycode inscription in the Namecoin blockchain, but as far as we've seen, the are all trivial compared to
BitLen in terms of artistic value/size.---BEGIN TRIBUTE---
#./BitLen
:::::::::::::::::::
:::::::.::.::.:.:::
:.: :.' ' ' ' ' : :
:.:'' ,,xiW,"4x, ''
: ,dWWWXXXXi,4WX,
' dWWWXXX7" `X,
lWWWXX7 __ _ X
:WWWXX7 ,xXX7' "^^X
lWWWX7, _.+,, _.+.,
:WWW7,. `^"-" ,^-'
WW",X: X,
"7^^Xl. _(_x7'
l ( :X: __ _
`. " XX ,xxWWWWX7
)X- "" 4X" .___.
,W X :Xi _,,_
WW X 4XiyXWWXd
"" ,, 4XWWWWXX
, R7X, "^447^
R, "4RXk, _, ,
TWk "4RXXi, X',x
lTWk, "4RRR7' 4 XH
:lWWWk, ^" `4
::TTXWWi,_ Xll :..
=-=-=-=-=-=-=-=-=-=
LEN "rabbi" SASSAMA
1980-2011
Len was our friend.
A brilliant mind,
a kind soul, and
a devious schemer;
husband to Meredith
brother to Calvin,
son to Jim and
Dana Hartshorn,
coauthor and
cofounder and
Shmoo and so much
more. We dedicate
this silly hack to
Len, who would have
found it absolutely
hilarious.
--Dan Kaminsky,
Travis Goodspeed
P.S. My apologies,
BitCoin people. He
also would have
LOL'd at BitCoin's
new dependency upon
ASCII BERNANKE
:'::.:::::.:::.::.:
: :.: ' ' ' ' : :':
:.: _.__ '.:
: _,^" "^x, :
' x7' `4,
XX7 4XX
XX XX
Xl ,xxx, ,xxx,XX
( ' _,+o, | ,o+,"
4 "-^' X "^-'" 7
l, ( )) ,X
:Xx,_ ,xXXXxx,_,XX
4XXiX'-___-`XXXX'
4XXi,_ _iXX7'
, `4XXXXXXXXX^ _,
Xx, ""^^^XX7,xX
W,"4WWx,_ _,XxWWX7'
Xwi, "4WW7""4WW7',W
TXXWw, ^7 Xk 47 ,WH
:TXXXWw,_ "), ,wWT:
::TTXXWWW lXl WWT:
----END TRIBUTE----Code 1.
Len Sassaman tribute
. 
Official portrait of Ben Bernanke (2008)
Source. Reference image from Wikipedia for the ASCII art.
Black OPS of TCP/IP by Dan Kaminsky (2011)
Source. Presented at the BlackHat 2011 conference. Dan unveils the Len memorial at the given timestamp around 8:41. The presentation was done on 2011-08-03 or 04, so very few days after the upload to the blockchain.From the JSON transaction we understand the encoding format:So it is really encoded one line at a time in the
"out":[
{
"spent":false,
"tx_index":0,
"type":0,
"addr":"1CqKQ2EqUscMkeYRFMmgepNGtfKynXzKW7",
"value":1000000,
"n":0,
"script":"76a91481ccb4ee682bc1da3bda70176b7ccc616a6ba9da88ac"
},
{
"spent":false,
"tx_index":0,
"type":0,
"addr":"157sXa7duStAvq3dPLWe7J449sgh47eHzw",
"value":1000000,
"n":1,
"script":"76a9142d2d2d424547494e20545249425554452d2d2d2088ac"
},
...
{
"spent":false,
"tx_index":0,
"type":0,
"addr":"157sXYpjvAyEJ6TdVFaVzmoETAQnHB6FGU",
"value":1000000,
"n":77,
"script":"76a9142d2d2d2d454e4420545249425554452d2d2d2d2088ac"
}script of the transaction outputs. Astronomy Updated 2025-07-16
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United States Armed Forces Updated 2025-07-16
Legendre's three-square theorem Updated 2025-07-16
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