Connected components of the orthogonal group Updated 2025-07-16
The orthogonal group has 2 connected components:
- one with determinant +1, which is itself a subgroup known as the special orthogonal group. These are pure rotations without a reflection.
- the other with determinant -1. This is not a subgroup as it does not contain the origin. It represents rotations with a reflection.
It is instructive to visualize how the looks like in :
- you take the first basis vector and move it to any other. You have therefore two angular parameters.
- you take the second one, and move it to be orthogonal to the first new vector. (you can choose a circle around the first new vector, and so you have another angular parameter.
- at last, for the last one, there are only two choices that are orthogonal to both previous ones, one in each direction. It is this directio, relative to the others, that determines the "has a reflection or not" thing
As a result it is isomorphic to the direct product of the special orthogonal group by the cyclic group of order 2:
A low dimensional example:because you can only do two things: to flip or not to flip the line around zero.
Note that having the determinant plus or minus 1 is not a definition: there are non-orthogonal groups with determinant plus or minus 1. This is just a property. E.g.:has determinant 1, but:so is not orthogonal.
Con of superconducting qubits Updated 2025-07-16
- requires intense refrigeration to 15mK in dilution refrigerator. Note that this is much lower than the actual superconducting temperature of the metal, we have to go even lower to reduce noise enough, see e.g. youtu.be/uPw9nkJAwDY?t=471 from Video "Building a quantum computer with superconducting qubits by Daniel Sank (2019)"
- less connectivity, normally limited to 4 nearest neighbours, or maybe 6 for 3D approaches, e.g. compared to trapped ion quantum computers, where each trapped ion can be entangled with every other on the same chip
Conservation laws in Schrodinger equations Updated 2025-07-16
TODO is there any good intuitive argument or proof of conservation of energy, momentum, angular momentum?
Consistency Updated 2025-07-16
Construction and management simulation Updated 2025-07-16
Content moderation Updated 2025-07-16
Continental drift Updated 2025-08-08
How Plate Tectonics was Discovered (1970)
Source. Produced by Simon Campbell-Jones Continuity equation Updated 2025-07-16
Continuous problems are simpler than discrete ones Updated 2025-07-16
Basically, continuity, or higher order conditions like differentiability seem to impose greater constraints on problems, which make them more solvable.
Some good examples of that:
- complex discrete problems:
- simple continuous problems:
- characterization of Lie groups
Continuous-variable quantum information Updated 2025-07-16
It is also possible to carry out quantum computing without qubits using processes with a continuous spectrum of measurement.
As of 2020, these approaches seem less developed/promising, but who knows.
Control engineering Updated 2025-07-16
Controlled language Updated 2025-07-16
Convert bytes to hex from Linux CLI Updated 2025-07-16
- no formatting;
- stackoverflow.com/questions/2614764/how-to-create-a-hex-dump-of-file-containing-only-the-hex-characters-without-spac
- unix.stackexchange.com/questions/10826/shell-how-to-read-the-bytes-of-a-binary-file-and-print-as-hexadecimal/758531#758531
- stackoverflow.com/questions/2003803/show-hexadecimal-numbers-of-a-file/77262369#77262369
- stackoverflow.com/questions/9515007/linux-script-to-convert-byte-data-into-a-hex-string/77262375#77262375
Convert PDF to text Updated 2025-07-16
Cool data embedded in the Bitcoin blockchain Bibliography Updated 2025-07-16
Other Bitcon analysis:
- "Annotated blockchain project"Does the same as this page, just that it is an uncomprehensible mess of broken links. But they have soe good ideas!
- etherpad.mit.edu/p/r.e33d2e7230fafc0612a0f2e7ebc87bae
- etherpad.mit.edu/p/r.19b7b3e2c5ea08a61cb0bef0aeb213fd image list (February 8, 2017) We tried going over it, but it is just too much work, the huge majority of the results are just AtomSea & EMBII so not that interesting.
- archive.ph/Zz7m5
- www.reddit.com/r/Bitcoin/comments/5wax5v/a_group_is_working_on_building_a_fully_annotated/
- archive.4plebs.org/pol/thread/111742853/
Their main techniques seem to be:and:mkdir binout for file in blk*dat; do echo "$file"; binwalk --dd='.*' "$file" -C binout/. --log=binout/"$file""res.txt"; donewhich seem promising.mkdir subfileout for file in blk*dat; do mkdir subfileout/"$file"; done for file in blk*dat; do echo "$file"; hachoir-subfile --category=image,video,audio,container,archive,misc "$file" subfileout/"$file" > subfileout/"$file""subfile.txt"; doneTODO how to they automatically map back to transaction IDs? There is a line "Script to add the TX ID to each file." Our attempts: Section "Get transaction id from position in dat file"
Cool data embedded in the Bitcoin blockchain cryptograffiti.info Updated 2025-07-16
twitter.com/cryptograffiti (marked as joined March 2014)
At some point it stopped using Bitcoin mainline and moved to Bitcoin Cash instead: www.newsbtc.com/news/bitcoin/cryptograffiti-rejects-bitcoin-core-bch-now-available-payment-method/ and therefore became useless. Existing indexes seem to have been broken as well.
Also, based on the timing of Figure "Erich Erstu", this service may be responsible for a large part of the raw JPEG images present in the blockchain from block 416527 (2016) onwards. This is also suggested by the comments at Figure "Tank Man".
A Quantitative Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin gives the interesting insight that all its transactions seem to return change/fees to one or two given addresses, thus making it very easy to list all their uploads if they were consistent! So all we need are some starting points, which we have mostly due to ASCII mentions of the site on known inscriptions, all of which have a few common spent addresses at the very end:so we just have to solve get all Bitcoin transactions from and to a given address and we are done. Blockchair shows about 800 entries as of February 2024, between 4f94f97eb156b8563a213bb292314a0bd9c95b39afc521fc5965d050daab2a78 (2014-03-02) and ac5f4ea03597b43a72fb8ab42bd5384629f87f4f4abc534f38b8c15148ccaf9f (2017-10-12): blockchair.com/bitcoin/outputs?s=time(desc)&q=recipient(1MVpQJA7FtcDrwKC6zATkZvZcxqma4JixS)
- 4c903a377addab7c1e35a685d3dabc664199e406374b1e5ce2fc59e78fb5b754: 1MVpQJA7FtcDrwKC6zATkZvZcxqma4JixS
- 87aad85c6cd75a516789f364637d243c668e3424d031ae510e43c6edfe6ed206: 1MVpQJA7FtcDrwKC6zATkZvZcxqma4JixS
- c206e8fff656f07b27dac831ef9b956792bae4e76a2cb43f14f49f0298bf2c2f: 1MVpQJA7FtcDrwKC6zATkZvZcxqma4JixS
- ca4f11131eca6b4d61daf707a470cfccd1ef3d80a6f8b70f1f07616b451ca64e: 1MVpQJA7FtcDrwKC6zATkZvZcxqma4JixS
Other related transactions:
- tx 87aad85c6cd75a516789f364637d243c668e3424d031ae510e43c6edfe6ed206 block 474652 (2017-07-07) via cryptograffiti.info the default pandoc markdown pandoc.org/try markdown tutorial string! First, unseen in our ASCII dumps due to UTF-8 encoding::followed by:
Unicode test: `Ä Ö Õ Ü ä ö õ ü`.And if ends with:An h1 header ============ Paragraphs are separated by a blank line.Uploaded from http://cryptograffiti.info to demonstrate Markdown rendering.
TODO understand what these are:
- ae92dc4c31943955ad6e3e45a4eb0067f488fdd9aecca65c946460dd2a85488d
- 3020dbd7c850bf8c19ebacf670a2830fe50999a8b2560a202af21d536760eea4
- d65384a21cb1c327cc42416a0b1e2a78ad0296cb7a15312bdcd67ef169ecb309
- a3e3100d2b9a86e310430945c001df97a70626220a9e151208aecbb613f1f152
- a9c82ebc47fabd1eed7eeea7760d0a3c99288af3c3a17e396ec790fc280698a2
- 92bfd5c0fb0f24efa6ca568c4475f44e94dfc8d0d4d5da04dfafc6261bf17f45
- 73c22adb21b93f9220d00d2614a50350824be95b8ea966349e6f35fe5ac5537b
- 099c0fd06d18953c886121ff143ea0a20d0baf29999f424fa1ac707a81cf4987
- 3ad6677303fb6f700a4f2f977fe86e5324e0ddb0d3b33a649e513d7e88904e85
- 31a2ddaf4b146e021246e1f82e28121f5c9c8729620978309004515c7e559910
- adaae897fd286aefb64a69e88a53e9af17ee98611ea595c3c92d038f3274d723
- d8bf48e9ad3de62c695ff34a96e340912bd62e0a0282b94da6386b837c31a30d
Cool data embedded in the Bitcoin blockchain Cursed ordinal Updated 2025-07-16
These were ordinals that were only indexed in later versions of the script. So to prevent changing the useless indices of existing ordinals, they gave them negative numbers.
Some examples:
- ordinals.com/inscription/4b9a822a057743813efbefa0dd21d0a01342ee793ce2ce5bd499a5f262187553i0 first inscription with no mime type.
- ordinals.com/inscription/2fa287270e4203ca2fc9f82ea3de7a0f7b785875791a76387ef6f4ccbb54eee2i0 is -38:is bugged because it is missing the mime type, on Python:because the
[b"'a\xf9\x19X%\xa8Q\x87SP\xe5\xf2H\xa6\xeew\x0e\x81\xa5hl\xcd\xaa\x97e\xfeqJ\x16\x12?", OP_CHECKSIG, 0, OP_IF, b'ord', 1, b'text/plain', 0, b'Hello World, this is a Rust Taproot test\xe2\x80\xa6', OP_ENDIF]1should instead beb'\x01.
Cool data embedded in the Bitcoin blockchain Encrypted data Updated 2025-07-16
Transactions such as tx fe37c7eee73be5fda91068dbe0eb74a68495a3fc7185712b8417032db7fc9c5e (2015-01-15) starting withare Base64 encoded. Running them through we might as well give up. That string appears 26 times in our data currently, between 6c091e6152b83ec0df8d0d87c7c5f3da72a3328ed3a5d91768ba0ab899c16b9d (2014-09-28) and 84189c82995db355e92e37f8cfe8a9274e9a5d157f1f1658067672e707469a09 (2019-07-06)
U2FsdGVkX1/4iSjLxQ5epo8eRSCOQLGgAsn1CucGii27k8ZyC7Jz6wxhYcevVmxi
6Q4ZFN04WDN0UhKqYardgQf26oeBMURupduDd0ZozxlgMrBkFOCaARqU7RABVWDO
/ruPUcOY0VC8p4lrMNqSdqvN7y6OWwOSH3c0duumZfFNZs9+BbtKCxtaqR5+RkUIbase64 -d leads to starting output bytes Salted__ which as mentioned at security.stackexchange.com/questions/124312/decrypting-binary-code-from-a-base64-string is OpenSSL encrypted data. So hwerever we see the start:U2FsdGVkX1/The following via cryptograffiti.info get marked by
file as "openssl enc'd data with salted password, Base64 encoded":- ad3d8a0a5d57114b1780341cb5104284f029bb01b1b3558f7c7b9ce51eb67e18
- 1cd0c631f444d664601468f644b70e0166019a54d8678de51310139b6c8b2bd7
- ccc3fb2c9cb1c640b76645a8658693066fd63433ab17c318691ad5bd62601c0e
- e6eb0cb8268a9b3d012d2957b32d4b28ccc3317593f54f4bfe4b387326588bd2
- c40e322b198b715accc4a67fad244ed131b8cef0785070e06d10d56c4ab389f2
- 37a261ac6dbf59e3c9673a22028bcdbdd08926a9d32134ab8fba0897f6dcd196
- f1aa516fe00ec2156f16fcb9da422f6cbcd141e8e58c895d8bc37b4ad2fd714e
- 7faf29c7dd7d9cc6d099c262f7ec7edd7fc768276482ad66ceefdd814f1d38ab
- 69cac244051661cc0b8b08905af5ab312a1282b68c932e5d1e3c46ad47ff0f7a
- 1773c39f844951b7169dc34aa0c72aa7b43cae6a103ed1223527ef0f4deec2a9
- b1d4bf3fc46e63c995ad4299f3576340077bc810dfa5c502d1c068460d54bc98
- a52625837741902e1dd24de3dbd3b948d6e0907ad3fc957c13cdf53fa2c3b9ac
- 4ca742813eaccef009e24e92150dda06540c2ac81782f1569b1ebb3179a413d2
- 6c3bab5fc6e6352c62a16ab0f47394845aa41a2c0b25e1a1073a4aeac150e03d
- 20b8feef3d293a0dd79e3c169fceb1217465502a523acbab903a7eb0cd183709
- b7863215b99567bc9e71155b13f3c5f26d15eac52493ee2e834129460ffd2aec
- 2c8961a64bb11d5855790085f51007273467f7ef862137215c9f1d958dcb6c57
- bed542957bdd8f644a4fcd671a8c66a5cc5d6168f9fa60d37177703e77558eee
- 3e45af9d828754d5a38c86636a070610f6e828482718c4a597d272d41a3e31fa
- a13af4817e85cacce3cfb445001e2fb2f56cdc30f78348fd2580bf8f4c84dc55
- 87a10f6bc65a08067b2544e46be00d4af62c0cfed3ae0b165d5eedaff09d81da
- ef55826befabbe9dcd44d87fc385d600dd4c4cba3346cde53d8c591960e9b4dc
- 5d30f63131dcf2b4d001b4ab530e18cc6ff8ffd16cade055ff4587a59b84e420
- 8a75514829b6e30b9fea434eef77b1589ff3f4bdfc0056bd087efbfb8314eb59
- e2be1062c9d43cc6ed43de6f7a40c728d2d92ed0325abde24ff3300cf3ae136a
- 8fe5c2679237e36c74fda04bb083f732c4afdd06af81121b1d7b4d5bd677135f
- 7f099f094d8d51105d8655253d45ebddf1c88b9e138c302a65d2878a237e620c
- 0fc4b3a305e2a7faa2e7d9c2f23d23d626e9e75f1f2a37133f283334b314645b
- 933b321e7b7144ed5e4e1750f944be9ed10293633d9b288bf05febdeb9dc40a3
- 6215486bc024dea7991b142e50e111c4063e1db4a867514612b8e794b8ef5635
- fc0613e11269962d97373b10e310f451fb76c7bb477ba1afb45773c44851e9ed
- ab51d2c037b4625394c68706da83c26bad751018d2a3e377a51988bd8ee18647
- 7ca9b337172f4feff67a0ecbfbd76798265e08c6ebe989a319883c695d756247
- 0f0b477e456dcf286d7262497bcd5b3b6a3ce89f81761c2f59ff702539ab6183
- a320152fd59426c8853dd781db9d682f89755953b39a653f9e9c9628a5fce7fb
- e96221da774fb52d24dda1b83b14c99085eb4befac64691722c56eb750562d68
- a7a5ca68dd340dd42bd5c91e0febe68e5fd2fb993da2992661183eaafe8ad89e
- 64e9d95e2333cfd155506199c8d926649e63a98dbc83c1221b8dd1580937b942
blockchain.news/news/mysterious-bitcoin-inscriptions-a-puzzle-in-raw-binary-data mentions a huge 9 MB Ordinal ruleset inscription that no-one managed to decode, and so people suspect is encrypted data. Seems to be split across transactions, starting at fed7de7fb75a3fe3c1acbbd8e19a4c540fb368474c8834e4ddb1d5bab764a767
Craig Silverstein Updated 2025-07-16
Cool data embedded in the Bitcoin blockchain HHTT Updated 2025-07-16
The Horrible Horrendous Terrible Tremendous Mining Pool inscribed a few cute Coinbase messages during their operation in 2012-2013.
Many of their messages also mention
SockThing, which was part of their mining infrastructure:Starting from their very first ASCII transaction on block 197602 (2012-09-07), there is what seems to be a poem spread across several transactions. Some of the lines are repeated, presumably because they didn't update the current line to a new line and so mined the same thing multiple times:The sentences are not very coherent together, perhaps this is because lines were chosen by different miners one at a time.
I am a pretty princess
covered in mud and blood
water with stuff in it
like everything else that wiggles or jiggles
screaming might not be your waY
see no reason to operate otherwise since
came into the world naked, wet and screaming
but silence will never be mine
until I am dead
but the smell will also give that away
gather all my things
load them in a big boat
airlift that to Kansas
and light it on fire
drop it from 7,000 feet
then railgun my corpse straight down
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