Yooooo,
I've been here on SN since the early beginnings and I'm very happy to be doing an AMA today. Here is my Twitter profile. I would love to talk about science, Bitcoin adoption, Bitcoin and Lightning development, and how Bitcoin might change in the future. I'll summarize a few points about me below and I'll be answering questions from today 10am CT / 16:00 UTC / 17:00 CET – Looking forward to this!
TL;DR: Bitcoin is not digital energy.
  • I live in Europe (rekt?).
  • I'm a theoretical Physicist by training and I work as a researcher doing research. My areas of expertise are in mathematical modeling and more specifically in Dynamical System Theory, Chaos Theory, Network theory, (very large) numerical simulations.
  • I've been programming since forever. I love open source software. The FOSS movement is one of the things in our world that I'm most optimistic about going into the future. I think we can build a whole civilization on the ideals of open source, which is why I'm so happy that Bitcoin exists.
  • I've known Bitcoin for a few years but my knowledge about Bitcoin expanded greatly when I started writing code for it. In retrospect, I needed Lightning to be a thing to start developing in the Bitcoin space. Lightning allows you to play around and mess with things without losing everything. It feels a lot more approachable than Bitcoin on-chain development. I think that's why we're witnessing this Cambrian explosion in Lightning development.
  • I've been developing in the Bitcoin space for a bit over a year now. Since then, I've accumulated quite some proof of work working with fantastic people (gh)
  • LightningTipBot: a Telegram Bitcoin Lightning wallet with many features. This is our fun and happy bot that is made for absolute noobs who haven't used Bitcoin before. Building it was a valuable exercise in UX design, since I rarely build things with an user interface. This bot is also our testbed for the latest and greatest Lightning features. We've experimented a lot with all things LNURL, noncustodial features, shops for digital items, paying for API calls (OpenAI stuff) and so much more.
  • Electronwall (gh): A tiny firewall for LND nodes. Since I'm managing economically active Lightning nodes, I needed a way to automatically decide which channels to accept and which not, so I built this tool. In the newest version, it allows you to get node information from Amboss/1ML before deciding whether you want to accept an incoming channel or not. I think that, as long as Lightning bears a risk of losing all your funds due to an accident or a hack, users should be careful with putting their money into a multisig with people they don't know anything about. Especially if you don't know exactly the risks you're taking on a technical level. I know this is a spicy topic which is why I mention it here and hope to have a fruitful discussion on. Lightning is scary.
  • LNbits (link): You might have heard of LNbits before. If not let me summarize it real quick. LNbits is software you can run on your own Lightning node and supercharge it with countless useful features. Some people call it a swiss-army knife for Lightning nodes. Others call it Wordpress for your Lightning node. It supports a ton of different funding sources (LND/CLN/Eclair/...). It has many extensions that I can't summarize all here. The reason I fell in love with LNbits was the API access it provides to your funding source. If you want to build Lightning-enabled software, you typically don't want to spent a ton of time building the Lightning rails, you want to focus on building your app. LNbits allows you to do that. By "abstracting away" the funding source, you can just use its excellent API for all things Lightning. Did I mention that LightningTipBot runs on LNbits? That's also why I started contributing to the project about a year ago and later became one of the core core devs of LNbits. Now I'm working on it every day.
  • Cashu (link): This is one of my most exotic projects so far. Cashu is a Chaumian ecash system built for Bitcoin. I'm sure I'll explain what Chaumian ecash is today but the most important thing to know about it is that it allows you to build privacy-preserving custodial Bitcoin apps. You can build wallets where the server doesn't know you, your balance, and who you transact with. Obviously, this is an insane improvement over classical ledger-based accounting systems. Interestingly, ecash has been around since the late 70s but its earliest iterations were built in fiat (a foundation of sand). It took us decades to come up with Bitcoin and blow the dust off this beautiful system called ecash to see if we can make use of it in a Bitcoin world. Turns out, we can.
Well that's a wall of text. If you made this this far and there was something you found interesting, let's chat!
Cashu:
  • Who runs the mint?
  • How is eCash swapped with lightning?
  • How do foresee smart contract applications emerging that utilize Cashu? How trusted would these applications be and can any sort of global state be maintained for them if it is all based on LN?
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Mint is centralized as far as I know. It is similar to Hosted Channels though.
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Yes, and hosted channels are a very good use case for chaumian ecash. Everything you know about HC's stays the same with the difference that the host gives you ecash instead of tracking your balance in a database. You can then exchange this ecash with other HC users or just use them for making payments over the channel without the host knowing about you.
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"Host tracking" balance the same way LN node does with regular channel. However, is ecash token really stateless? I doubt host shouldnt ensure accountability.
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  • Everyone can run a mint, there is not only one.
  • Via the mint exchanges tokens for LN payments.
  • You can program a token itself but the execution of the "contract" is done by the mint. The There is no blockchain or anything. You trust the mint. There is no global state. It is not "baked into" the Bitcoin or Lightning protocol.
I hope that makes things a bit clearer.
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How many people are behind the handle "@calle"?
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your split personalities are in an m of n multisig!
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if you could change one thing about the lightning network, what would you change?
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Backups and security. I wish we wouldn't have to worry about them as much. If I could choose anything, even unrealistic things, I would want the Lightning network to be as simple as on-chain: Backup your keys properly and you'll be ok.
I think we're on a good path with Eltoo (which eliminates huge parts of the headache that backups cause today) and things like the Blockstream's Greenlight and VLS.
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Is Bitcoin digital energy?
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No.
Ok, I'll bite: It always puzzled me how Bitcoiners, who I think are people who question the nature of money and what it is or can be, fell for this energy battery narrative. It's clear that Bitcoin uses energy for mining (which is then lost as heat to the environment) but it's beyond me why people believe that the fact that it can be used as money and make someone else on the other side of the planet move physical objects by paying them to do so makes it any sort of energy. Saylor did this.
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I don't regard the energy used in Bitcoin mining as lost. At the global level, all that hashing energy was required to create new bitcoins, so the energy served it's purpose; the heat being a by-product.
I can envisage each bitcoin as a representation and manifestation of all that global energy used in the hashing, and since bitcoins reside in the digital realm, I don't see the digital energy moniker as problematic.
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Agreed. It makes the community appear naive to anyone with a 101 understanding of monetary economics.
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I'd argue that money. especially bitcoin, is an abstract manifestation of productivity (store of value). It may not be a store of energy, but it does act as a battery in a sense of value that can be used later. Combine that with the ability to use it globally almost instantly, his point still stands IMO.
People who actually believe that bitcoin is literal energy are completely missing the point, which I don't believe you are saying by the way.
Maybe "energy" is the wrong word, but it's a decent metaphor in my opinion.
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It's a battery of value.
Value creation requires energy, directly or indirectly.
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да. если ты можешь её обменять на что то похожее. например $ на газ. или сатоши на подписку.
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If you weren’t full-time on LNBits, which other projects do you believe you would be dreaming up or working on?
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I would love to dig deeper in Bitcoin and Lightning implementations one day.
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I remember when you first put cashu out, the blind signature scheme was (or at least looked like) a quick python implementation of a gist that rubin somsen wrote. It looked like waxwing and a bunch of other folks have chimed in on the gist about the soundness of the scheme, but I haven't been following it. What's the state of that whole thing.
Also, why do people keep coming up with bad metaphysical analogies for bitcoin?
Love your work and appreciate all you do. Hope you have a nice holiday season.
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Hey man! Thank you. Yes, I followed those discussions, I think scheme is pretty solid. Most of the issues that came up are really implementation-based. Coding up the basic mechanics in a few days was a real trip!
What still fascinates me is that the equations for the blind signature scheme used in Cashu can be summarized in a couple of lines. Here is the gist that @rijndael was referring to: Link
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How do you get the headspace and energy to work on so many exciting BTC projects at the same time? I am gasping for breath just by reading your introduction lol
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lol thank you and sorry! I tell myself that a (healthy) obsession is one of the best things that you can have in life. Any energy and motivation you feel inside is a gift you should cherish since stasis comes way too soon as you get older. It's too bad that life is so damn short.
I don't know how to get you the headspace but what works for me is routine, workouts, good food, fun on the weekends, and a problem you can work on that is way bigger than your personal life.
I also recommend meeting Bitcoiners in real life. It's more motivating than anything else.
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Excellent write up. Sounds like you are on the cutting edge of lightning development. Personally I am very excited about LNbits and Cashu from a user standpoint. I'm curious as to whether you have played around on nostr, and if so, what are your impressions?
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Thank you! Yes, I have played with nostr for the first time just this weekend. Already preparing an update for the Cashu CLI client to send ecash from one wallet to another using their nostr pubkey. It's working!
I love how nostr got a healthy push, it's a great community effort and there is an impressive number of tools and implementations for it available. The biggest lesson for me is that simplicity is key for developer adoption. It's very easy to build a nostr app!
I'm a bit worried about the spam and relay resource problem though. It will be very interesting to watch how different attempts at preventing spam maybe by charging users will play out and also how the relay network will evolve. To my understanding, the resource requirements are considerable and we'll see how these limits will affect the UX.
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could use cashu to prevent spam
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Wow you already said everything, you didn't leave us any question to ask 😂😂😂😂😂😂
Just joking man, great work you are doing!
I have only ONE question for you: Do we win?
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Thanks!
We do win! For many different reasons, bitcoin will keep growing and that's the most important thing.
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I will tell you a secret: we already won, but the banksters are still in agony now. Enjoy the ride 😂😂😂😂😂😂😂😂😂😂😂😂
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what caused chaumian ecash ideas on bitcoin to come back into style recently?
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My take would be that the internet needed a native currency for the idea to truly flourish. Imagine trying to build a privacy-preserving fiat banking system today. Never gonna happen.
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makes sense. it seems like ecash enthusiasm really just picked up in the last year or two (or maybe i wasn’t paying attention).
why haven’t we seen many other ecash projects in the last decade?
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How does your Network Theory simulation work serve you in your Lightning learning/work. What if Electronwall took off?
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I'm accustomed to thinking in networks and have implemented network algorithms myself before which probably makes it easier to imagine how the lightning network works and what the possible routes for optimizations could be. It's a rather unexplored area (which shows how early we are) and most node implementations use very basic algorithms and heuristics for path finding. I'm happy that Rene Pickhardt's work on payment flows and reliability took off like it did because it's a reminder that the most basic research tools (methods) we have in math and network science aren't being applied on the LN yet. I hope and expect a lot more to happen in this field.
What if electronwall took off? Well, I think before that we'd have to ask whether the Lightning network as it is being "deployed" today is the right and responsible way. Should we be pushing for non-technical people running a node with potentially risky financial software in their homes? Are these people responsible for building a network with random topology? This happens at the same time as big professional node operators are using sophisticated security software and are mainly opening big channels to other big players.
I really don't know but I think the random network approach is not sustainable as long as there is considerable risk in running a node.
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When do we get Standard Sats hedge service in Lnbits? :-D https://github.com/lnbits/lnbits/pull/1025
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I was just looking at that PR a couple of minutes ago! I still need to sit down and crunch through it, so many things happening in LNbits at the same time! It's crazy.
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What are your thoughts on the future of lightning node operators? How do you think the network will evolve to enable more merchants, businesses, and individuals to onboard to the lightning network in a safe manner (as in without risking the loss of their funds)?
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Also curious how you view centralization risks of a few large players routing the majority of transactions.
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Thank you for all your great work calle!
I have a question about cashu:
Since the mint is like the centerpiece, where the users can redeem their cashu tokens, it seems like a single point of failure. Is there a good strategy to implement redundancy? Could one run multiple instances of the 'same' mint?
I guess what i'm asking is, does the mint have a state that would need to be shared between instances? If yes, what would be a good way to do that?
I watched your presentation on cashu, it was really good, and easily understandable for a chaumian ecash newbie.
Also, cool outfit!
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Hi! Yes, redundancy can be implemented quite easily. The mint has only one state which is the list of tokens it has seen in the past. You can have many mints (who MUST trust each other) accessing the same database of seen tokens, that way you can add redundancy very cheaply.
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Awesome! Thank you.
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What do you think about the last finding on the chaotic pattern in this research? https://www.pnas.org/doi/10.1073/pnas.2209601119
What was the most fascinating thing you've discovered while studied Chaos Theory? Personally, I'm not sure if it was the logistic map topic or the 0-1 test for chaos.
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That's an interesting paper! I'm not an expert in cell biology but I must admit that I'm not very surprised that they found chaotic behavior in such a high-dimensional system but the experimental observation is fascinating nonetheless!
I'm much more common with chaos in dynamical systems than in maps. One of the most intriguing observations that I came across is the fact that you need a minimum of three dimensions to observe chaos in a dynamical system. Two dimensions mean that you'll be limited to either stable limit cycles, fixed points, or a divergence to infinity. Only with three dimensions, you can "escape the circle" into another dimension. The simplest one I know of such systems is the Lorenz Attractor.
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I would like to get started with development on top of lightning, I know some React and JS, what would you recommend? any good first issues you recommend? thanks
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Sounds like you could be a pro for building wallets! Actually, if you're interested in helping out with Cashu with exactly those two skills (JS and React) you could be the first person to implement a native mobile wallet! It's fairly easy to do, the only complicated part is the token cryptography but that's all already implemented in the LNbits web wallet and basically copy and paste.
Let me know what you think, you can hit me up on Telegram or Twitter under the handle "callebtc".
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Sure, I will ping you
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Here is a token for you!
W3siaWQiOiJLRDZBSlZFNDdTNXMiLCJhbW91bnQiOjIsIkMiOiIwMjcwYzBjYmVkOTUwMjJmYzdlMjE4NWFiNDAyYTJhZjEzZTE3ZDEwMTIwNTEyZTg3ZGUxMGUzMTZiODU3ODk1MjkiLCJzZWNyZXQiOiJpMHRyMzVwdHVpOERoajBjOGpoV1NoNWRpTk5ld3JPR1p6NTZwQUtVTmNFPSJ9LHsiaWQiOiJLRDZBSlZFNDdTNXMiLCJhbW91bnQiOjgsIkMiOiIwMzRmNWUwOGRjZjEzMmFlMzdmZGUzNmI1ZDQyOTE0MjBkNjlkZmNlYmM5NjNhZWNlNzZlZTQxZjE4YmEzZDA3ZDQiLCJzZWNyZXQiOiJSMVlmUEFJMEE1MmV3Ny9MZm9vYVFvMElXcUNiOWV4S1FUaEtUTWxiYTVVPSJ9XQ
It’s not much but thanks for building this so I can have fun!
Question: pizza or tacos?
@calle, which consumer facing products do you think will gain most traction on lightning, that we haven’t seen yet?
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Automated payments for all of your subscriptions, on the hour. Be it video streaming or the electricity bill. Why would you ever have monthly payments if you could have them hourly? As Bitcoin grows, I'm sure we will see that happening more often.
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What are some of the biggest problems you have found that could be solved with lightning products?
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Just accepting payment for stuff online, really. Killer app.
Imagine you build a small tool and put it on the internet but it costs money to run the service. What do you do? Apply for a credit card payments thing and wait 3 months for it to happen? Never gonna happen. Lightning it is.
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It was really such a delight to know you in a deeper level, really great to see people like you here man! By the way how does the ecahs system encountered with bitcoin and wioo there be available payments methods or cashout.
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Cashu wallets are meant to be Lightning wallets really. The difference being that you can't be tracked. The tokens only replace the ledger.
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Love LNbits, and lightning too, I contributed to some projects like OBW wallet and developped some app on the top of LNbits.
LNbits is really good for whoever wants to develop apps on lightning thanks to LNbits APIs, LNbits allows to have kinda abstraction layer between apps/ln backends without the need of being aware of the ln backend implementation
btw thanks for your amazing work.
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No lies detected 👆
Thank you!
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You mentioned picking & choosing particular lightning nodes to connect to. What do you look for in making that decision?
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Depends. For maximum security, many LSPs only connect to peers that they know and can hold accountable somehow. You might also have a whole network of nodes and want to make sure that you only open internal channels. That's what many Lightning service providers are already doing with their infrastructure.
For users and LSPs that want to keep their network open, choices could be dependent on node age (i.e. open channels with nodes that are at least 6 months old), high availability, channel capacity measures (only nodes with big channels as opposed to many small ones), network ping, Tor availability, etc.
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What worries you about the lightning network?
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Allow me to c/p from a similar question someone else asked:
Backups and security. I wish we wouldn't have to worry about them as much. If I could choose anything, even unrealistic things, I would want the Lightning network to be as simple as on-chain: Backup your keys properly and you'll be ok.
I think we're on a good path with Eltoo (which eliminates huge parts of the headache that backups cause today) and things like the Blockstream's Greenlight and VLS.
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Is this question seeking an answer from Rene Pickhardt in your area of expertise?
"Impact of the global cost function (weighting) to Betweenness Centrality distribution"
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Thanks for all your developments! It's Bitcoin real love!
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Thanks for your work man.
I live in Europe (rekt?).
Be safe, stay the f away from Netherlands.
Assume EU will ban Bitcoin because something something climate. What would you do?
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It would be devastating but then again, Bitcoin is designed for exactly those kind of adversarial scenarios. I'm not going to stop coding like many others!
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What is your favourite simulation method?
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Coding it by hand :)
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The token from one Cashu mint are not compatible with token from another Cashu mint (right?)
Would it be possible to make them compatible? i.e. I can pay ecash token from Cashu1 to Cashu2 directly (no ecash<-->LN<-->ecash involved). That is essentially what fediMint is trying to solve, isnt it?
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Hi! No, unfortunately there is no way to make that happen, even fedimint does not support that (that would be paying with tokens from one federation in the other).
We don't need to solve that though, because the idea is to use Lightning and handle the ecash exchange with multiple mints in the background. I hope we can get there, as I imagine an ecash future with a wallet having a multitude of smaller balances all over the place that you can easily move from a to b using Lightning.
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Great to see all the work you're doing. thank you.
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I am very concerned about tokenization built on top of Lightning. In what way would stablecoins, or even e-cash for that matter, be different to what the shittiest of all shitcoins are offering us today?
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How could Nostr relays use Cashu today to prevent Sybil attacks and prevent spam?
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What are you doing to not only better onboard new users, but more importantly orange pill the masses?
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In what ways has being a physicist made you a better programmer? In what ways has being a physicist made you a worse programmer?
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Why does Bitcoin feel spiritual to many of us?
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Interesting question. I think it's important to distinguish between two things that people refer to as "spiritual". There is the (cult-like?) group spirituality (like religion) and there is the more personal ethics-type spirituality (like ancient philosophy). While I consider the second one as an important part of life (and Bitcoin can very well be part of that), I'm much more suspicious of the the first type.
I once heard that every movement that grows too large invariably attracts new people in who bring their own ideology and belief system with them and will try to put those things into the center, often diverging from the original visions of a movement. I think it's similar in Bitcoin. Nevertheless, Bitcoin, thankfully, doesn't care.
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Привет. что то могу посоветовать. можете прочитать часть сообщений. вдруг что то станет яснее. много времени не отниму. спасибо.
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