An Introduction to the Mechanics of Bitcoin
khanacademy.org
khanacademy.org
However, far more importantly then bitcoin I want to know why the hell we don't have proof of work as an email spam filter yet!!!!!!
It's still a deterrent and makes it non trivial to be a spammer. Also even on botnets each node is large numbers of emails, so it increases the odds that the owner of the infected computer would notice all the work being done.
Makers of specialized 'spam' hardware could potentially be targeted by law enforcement easier then dispirit spammers (especially if the hashing algorithm could be designed to be specific to email systems).
I can see some arguments as to why it's not 100% effective, but I don't think it needs to be 100% effective to add additional value. That's why I'm amazed it's still not being done. Just like I'm amazed that we still don't have easy to use email encryption, yet demand it for the web (email traffic is far easier to eavesdrop on, and often far more sensitive).
If email clients maintained the wallets you wouldn't need to even worry about the cost if you had a balance of in/out mail. You could still white list anyone you want to email for free. A cost of $0.001 per message would have very little impact on regular users. A botnet would still need to get the funds somewhere to bulk send, if they cracked the mail programs internal wallet they could drain that and send a small number of emails, but beyond that they'd need funds, and quite frankly if they could get at the wallets they'd just take the money direct.
It raises an interesting question. what is the value to a spammer of an individual email? The return from advertising/scams/phishing/whatever divided by the number of emails sent. It's got to be tiny.
I wonder about mailing lists - a couple of thousand members isn't too big a list, but $1 a message adds up. Who pays it? What keeps someone from adding fake accounts to run up the costs of lists they dislike?
Because it's not very useful until nearly everyone supports it.
If a non-trivial amount of people don't implement it (which is highly likely when it's first released), then you have to accept non-proof-of-work-emails, or you'll miss the emails. That is the hole in the system that spam will get in through. So why bother supporting it yourself if it won't stop spam?
Secondly it is not that spam is a binary thing. You can use proof of work as another feature in your baysian system.
Of course the latter isn't perfect and comes with its own evil hegemony and other assorted issues, but the point is that there is so little barrier to entry to posting on the web that praising speed in and of itself ignores relevant and important issues.
Most people--even us self-motivated HN people--are far more likely to do hundreds of hours of coursework if there's a real class, human teachers, and other students than if it's online to pursue at your leisure, or in a book sitting on your shelf for that matter.
The overwhelming majority of my formal education (through high school and most of college) consisted of classes where most of the students either didn't want to be there, or weren't interested in the course beyond its impact on their grade and future transcript, and so were disruptive to the learning process.
And I doubt I'm alone in saying that.
I am not saying that this guy does a bad job but, in general, I avoid videos like plague after many bad experiences with them. Especially those where there is just scrolling text and some god awful soundtrack with it.
Firstly, nothing. No one said there was.
Secondly, from what I can tell, writing is inferior to the human physical expression, which includes speech. It exists to mimic and preserve thought or speech. But it can never be precise, simply because the human body augments speech. When writing gets close to accurately doing that, it become verbose and tedious.
Or, to put it another way: Would your kids prefer to read or be read to? Would you prefer the lyrics or the song? The script or the movie? You might, most wouldn't.
Atleast in the current context, books are faster to reread compared to rewinding a video, which can break your flow.
OTOH speech conveys emotion better and feels like it has less mental overhead to consume and produce. I know a few people who are excellent speakers but very poor writers for example.
I have a feeling this video would completely lose my mother.
http://www.bringhurst.org/2013/04/03/how-does-bitcoin-crypto...
Perhaps Sal doesn't have a great understanding of cryptography? He doesn't do a single cryptography video on khanacademy as far as I know.
https://www.khanacademy.org/humanities/history/euro-hist
We just like to put up good content from other authors too when we find it. :)