In the context of National Physical Laboratory (NPL) measurement science, "Time" refers to precise timekeeping and measurements related to time standards. The NPL is known for its work in developing and maintaining national measurement standards, including time and frequency standards. MSF (Master Standard Frequency) is a time signal transmitted by the National Physical Laboratory in the UK, which provides accurate time and frequency information to users.
Dubna is a city in Russia, located about 125 kilometers northeast of Moscow, on the banks of the Volga River. It is known primarily for hosting the Joint Institute for Nuclear Research (JINR), an international research organization that conducts scientific research in nuclear physics and related fields. JINR was established in 1956 and has played a significant role in various scientific discoveries and collaborations, bringing together scientists from multiple countries.
Bibliography:
- maths-people.anu.edu.au/~andrews/DG/ Lectures on Differential Geometry by Ben Andrews
By "Satoshi uploader" we mean the data upload script present in tx 4b72a223007eab8a951d43edc171befeabc7b5dca4213770c88e09ba5b936e17 of the Bitcoin blockchain.
The uploader, and its accompanying downloader, are Python programs stored in the blockchain itself. They are made to upload and download arbitrary data into the blockchain via RPC.
These scripts were notably used for: illegal content of block 229k. The script did not maintain its popularity much after this initial surge up loads, likely all done by the same user: there are very very few uploads done after block 229k with the Satoshi uploader.
Our choice of name as "Satoshi uploader" is copied from A Quantitative Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin by Matzutt et al. (2018) because the scripts are Copyrighted Satoshi Nakamoto on the header comment, although as mentioned at Hidden surprises in the Bitcoin blockchain by Ken Shirriff (2014) this feels very unlikely to be true.
A more convenient version of those scripts that can download directly from blockchain.info without the need for a full local node can be found at: github.com/cirosantilli/bitcoin-inscription-indexer/blob/master/download_tx_consts.py by using the
--satoshi option. E.g. with it you can download the uploader script with:./download_tx_consts.py --satoshi 4b72a223007eab8a951d43edc171befeabc7b5dca4213770c88e09ba5b936e17
mv 4b72a223007eab8a951d43edc171befeabc7b5dca4213770c88e09ba5b936e17.bin uploader.pyThe scripts can be found in the blockchain at:
- uploader: tx 4b72a223007eab8a951d43edc171befeabc7b5dca4213770c88e09ba5b936e17 block 229991 reproduced at: gist.github.com/cirosantilli/ade4dde7c2f2f5020d792872681763e8The uploader creates a standard Pay-to-PubkeyHash transaction with a single output and data as a fake pubkey hash, and sends change to an address specified on the command line:
./bitcoinInsertionTool.py <data> <change-addr> - downloader: tx 6c53cd987119ef797d5adccd76241247988a0a5ef783572a9972e7371c5fb0cc block 229991 reproduced at gist.github.com/cirosantilli/e90bd2e6c3fab25a20898e61e3ab3e90The downloader just strips all operands, and keeps all data, notably where public key hashes would be normally put.
The uploader script uses its own cumbersome data encoding format, which we call the "Satoshi uploader format". The is as follows:This means that if we want to index certain file types encoded in this format, a good heuristic is to skip the first 9 bytes (4 size, 4 CRC, 1
- ignore all script operands and constants less than 20 bytes (40 hex characters). And there are a lot of small operands, e.g. the uploader itself uses format www.blockchain.com/btc/tx/4b72a223007eab8a951d43edc171befeabc7b5dca4213770c88e09ba5b936e17 has a
OP_1, data,OP_3,OP_CHECKMULTISIGpattern on every output script, so theOP_1andOP_3are ignored. I.e., it is P2FMS. - ignore the last output, which contains a real change transaction instead of arbitrary data. TODO why not just do what with the length instead?
- the first 4 bytes are the payload length, the next 4 bytes a CRC-32 signature. The payload length is in particular useful because of possible granularity of transactions. But it is hard to understand why a CRC-32 is needed in the middle of the largest hash tree ever created by human kind!!! It does however have the adavantage that it allows us to more uniquely identify which transactions use the format or not.
OP_1) and look for file signatures.Let's try out the downloader to download itself. First you have to be running a Bitcoin Core server locally. Then, supposing we run:worked! The source of the downloader script is visible! Note that we had to wait for the sync of the entire blockchain to be fully finished for some reason for that to work.
.bitcon/bitoin.conf containing:rpcuser=asdf
rpcpassword=qwer
server=1
txindex=1git clone git://github.com/jgarzik/python-bitcoinrpc.git
git -C python-bitcoinrpc checkout cdf43b41f982b4f811cd4ebfbc787ab2abf5c94a
wget https://gist.githubusercontent.com/shirriff/64f48fa09a61b56ffcf9/raw/ad1d2e041edc0fb7ef23402e64eeb92c045b5ef7/bitcoin-file-downloader.py
pip install python-bitcoinrpc==1.0
BTCRPCURL=http://asdf:qwer@127.0.0.1:8332 \
PYTHONPATH="$(pwd)/python-bitcoinrpc:$PYTHONPATH" \
python3 bitcoin-file-downloader.py \
6c53cd987119ef797d5adccd76241247988a0a5ef783572a9972e7371c5fb0ccOther known uploads in Satoshi format except from the first few:
- tx 89248ecadd51ada613cf8bdf46c174c57842e51de4f99f4bbd8b8b34d3cb7792 block 344068 see ASCII art
- tx 1ff17021495e4afb27f2f55cc1ef487c48e33bd5a472a4a68c56a84fc38871ec contains the ASCII text
e5a6f30ff7d43f96f61af05efaf96f869aa072b5a071f32a24b03702d1dcd2a6. This number however is not a known transaction ID in the blockchain, and has no Google hits.
Solving differential equations was apparently Lie's original motivation for developing Lie groups. It is therefore likely one of the most understandable ways to approach it.
It appears that Lie's goal was to understand when can a differential equation have an explicitly written solution, much like Galois theory had done for algebraic equations. Both approaches use symmetry as the key tool.
- www.researchgate.net/profile/Michael_Frewer/publication/269465435_Lie-Groups_as_a_Tool_for_Solving_Differential_Equations/links/548cbf250cf214269f20e267/Lie-Groups-as-a-Tool-for-Solving-Differential-Equations.pdf Lie-Groups as a Tool for Solving Differential Equations by Michael Frewer. Slides with good examples.
Elements of a Lie algebra can (should!) be seen a continuous analogue to the generating set of a group in finite groups.
For continuous groups however, we can't have a finite generating set in the strict sense, as a finite set won't ever cover every possible point.
But the generator of a Lie algebra can be finite.
And just like in finite groups, where you can specify the full group by specifying only the relationships between generating elements, in the Lie algebra you can almost specify the full group by specifying the relationships between the elements of a generator of the Lie algebra.
The reason why the algebra works out well for continuous stuff is that by definition an algebra over a field is a vector space with some extra structure, and we know very well how to make infinitesimal elements in a vector space: just multiply its vectors by a constant that cana be arbitrarily small.
Bibliography:
Lie Groups, Physics, and Geometry by Robert Gilmore (2008) 7.2 "The covering problem" gives some amazing intuition on the subject as usual.
A single exponential map is not enough to recover a simple Lie group from its algebra by 
Ciro Santilli 37 Updated 2025-07-16
Ciro Santilli 37 Updated 2025-07-16 The product of a exponential of the compact algebra with that of the non-compact algebra recovers a simple Lie from its algebra by Ciro Santilli 37 Updated 2025-07-16
Ciro Santilli 37 Updated 2025-07-16Furthermore, the non-compact part is always isomorphic to , only the non-compact part can have more interesting structure.
Cool data embedded in the Bitcoin blockchain Len Sassaman tribute by Ciro Santilli 37 Updated 2025-07-16
Ciro Santilli 37 Updated 2025-07-16Tribute 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 _,,_
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, 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
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: :.: ' ' ' ' : :':
:.: _.__ '.:
: _,^" "^x, :
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XX7 4XX
XX XX
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----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.The most important example is perhaps and , both of which have the same Lie algebra, but are not isomorphic.
Every Lie algebra has a unique single corresponding simply connected Lie group by Ciro Santilli 37 Updated 2025-07-16
Ciro Santilli 37 Updated 2025-07-16This simply connected is called the universal covering group.
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 3. Visual Studio Code extension installation.
Figure 4. Visual Studio Code extension tree navigation.
Figure 5. Web editor. You can also edit articles on the Web editor without installing anything locally.Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.Video 4. OurBigBook Visual Studio Code extension editing and navigation demo. Source. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact