Serious question, why does HN seemt o be in favor of lightning over BCH’s approach of not neutering the block size?
LN has so many drawbacks. Have to always be online, need to hold hot walkets, need liquidity provided at both ends (kyc/aml)...
LN has so many drawbacks. Have to always be online, need to hold hot walkets, need liquidity provided at both ends (kyc/aml)...
Another important factor is the 10 minutes confirmation time, nobody wants to wait for 10 minutes at the counter before they trust you walking out. We need something with instant verification and low fees and increasing the blocksize will never do that.
I am surprised more folks on HN are not familiar with nano considering it is one of the few teams in crypto with endorsements from familiar faces: Zack Shapiro on the core team (ex-Product Hunt), Garry Tan (YC, angel investor in Coinbase), and Charlie Lee (former director of engineering @ Coinbase).
I suggest you actually read the Nano and IOTA white papers. They're very different.
Nano suffers from the same problem that 99.9% of cryptocurrencies suffer from: no useful information on how an average person might actually USE it.
Google brings various ways you can BUY Nano in order to speculate. I want to see real world usage, I want to buy VPN/Hosting/Alpaca Socks using Nano.
PS Nano is also 100% pre-mined which means one would have to investigate on who holds what percentages of these pre-mined coins. (case in point: Ripple)
You do not see it because you likely fall outside of the demographic of cryptocurrency first users: businesses and citizens in countries facing hyperinflation, black markets, gambling, porn users seeking anonymity, legal pot businesses in the west cut-off from traditional banking in the west, legal porn businesses cut-off from traditional banking in the west.
Bear in mind there is a lag in adoption of the best technology. Just 4-5 months ago bitcoin was still the dominant currency on darknet markets, now it is monero.
Now I agree that there is a niche for Monero in black markets.
Then there should be a huge opportunity for some crypto currency to take over Bitcoin in the role as a medium of exchange for general public.
Thus it really irks me that I am not seeing these supposedly revolutionary crypto currencies attempt to do anything useful.
Why doesn't any cryptocurrency focus on usability for a regular audience first?
I saw Charlie Lee's reddit post asking questions about Nano (https://www.reddit.com/r/nanocurrency/comments/80c6fg/questi...). Did he follow up with an endorsement?
The initial distribution of XRB was performed through
"manual mining" limited via a captcha.
The distribution rate was
17 XRB (Raiblocks) per hour per ip4.
https://www.youtube.com/results?search_query=raiblock+captch...
https://github.com/nanocurrency/raiblocks/wiki/Design-featur...
These users need new people to buy their Raiblocks / Nano in order to profit off this scam.
ICO's that promise guaranteed returns are scams. Nano is an open source project that aims to give people an alternative to government currency. https://trends.google.com/trends/explore?q=raiblocks The most interest as measured by google search activity in the world for raiblocks/nano is in Venezuela; you'll find a similar pattern of top search results coming from countries where citizens are looking for alternative currencies -- Kosovo, Cyprus, Greece, etc -- with other useful cryptocurrencies.
disclaimer: I interviewed with the team back in January and turned down a contractor role but was impressed with their mission and roadmap.
Measurably less CAPEX and OPEX for the first users to run the software "securing" the least important era of the network earned the greatest percentage of the supply?
Satoshi is even quoted as to the design of the ponzi like scheme:
Satoshi Nakamoto
Thu Jan 8 14:27:40 EST 2009
I made the proof-of-work difficulty ridiculously easy to
start with, so for a little while in the beginning a
typical PC will be able to generate coins in just a few
hours. It'll get a lot harder when competition makes the
automatic adjustment drive up the difficulty.
first 4 years: 10,500,000 coins
next 4 years: 5,250,000 coins
next 4 years: 2,625,000 coins
next 4 years: 1,312,500 coinsSatoshi could easily have designed the PoW to distribute more slowly, and favor long term growth as more users join the network. Instead only early adopters control the supply. The risk of this is catastrophic.
One important point: if we actually include all 7 billion
people on the earth, most of whom have zero BTC or
Ethereum, the Gini coefficient is essentially 0.99+. And
if we just include all balances, we include many dust
balances which would again put the Gini coefficient at
0.99+. Thus, we need some kind of threshold here. The
imperfect threshold we picked was the Gini coefficient
among accounts with ≥185 BTC per address, and ≥2477 ETH
per address. So this is the distribution of ownership
among the Bitcoin and Ethereum rich with $500k as of July
2017.
In what kind of situation would a thresholded metric like
this be interesting? Perhaps in a scenario similar to the
ongoing IRS Coinbase issue, where the IRS is seeking
information on all holders with balances >$20,000.
Conceptualized in terms of an attack, a high Gini
coefficient would mean that a government would only need
to round up a few large holders in order to acquire a
large percentage of outstanding cryptocurrency — and with
it the ability to tank the price.
With that said, two points. First, while one would not
want a Gini coefficient of exactly 1.0 for BTC or ETH (as
then only one person would have all of the digital
currency, and no one would have an incentive to help boost
the network), in practice it appears that a very high
level of wealth centralization is still compatible with
the operation of a decentralized protocol. Second, as we
show below, we think the Nakamoto coefficient is a better
metric than the Gini coefficient for measuring holder
concentration in particular as it obviates the issue of
arbitrarily choosing a threshold.
...However, the maximum Gini coefficient has one obvious
issue: while a high value tracks with our intuitive notion
of a “more centralized” system, the fact that each Gini
coefficient is restricted to a 0–1 scale means that it
does not directly measure the number of individuals or
entities required to compromise a system.
Specifically, for a given blockchain suppose you have a
subsystem of exchanges with 1000 actors with a Gini
coefficient of 0.8, and another subsystem of 10 miners
with a Gini coefficient of 0.7. It may turn out that
compromising only 3 miners rather than 57 exchanges may be
sufficient to compromise this system, which would mean the
maximum Gini coefficient would have pointed to exchanges
rather than miners as the decentralization bottleneck.
Conversely, if one considers “number of distinct countries
with substantial mining capacity” an essential subsystem,
then the minimum Nakamoto coefficient for Bitcoin would
again be 1, as the compromise of China (in the sense of a
Chinese government crackdown on mining) would result in
>51% of mining being compromised.
The systemic risk is outlined in the comment above.
Not even the darknet vendors accept Nano / Raiblocks.
Do you know any places where Nano XRP Raiblocks are being accepted?
You might want to read these:
http://steamcommunity.com/games/593110/announcements/detail/...
https://stripe.com/blog/ending-bitcoin-support
tl;dr cryptocurrencies don't really work for the real world.
Why doesn't Nano Raiblocks allow more users to generate new Nano/Raiblocks? Would that hurt your investment if every user had equal access to the production of the supply?
Why are you so emotionally invested in trying to sell these beanie babies to other people? Is it because you need to profit off other buying into your scam?
Still no list of businesses accepting Nano/Raiblocks?
One of the topics I enjoyed deep diving on the most was the lightning network. The two pain points I observed for lightning were: (1) It takes a non-trivial amount of energy to understand hashed time lock contracts well enough to be able to prove the concept to yourself. Not having as easy mastery of a topic off the bat leads to feeling less secure about one's ability to reason about security. (2) The specter of rising on-chain fees for commitment transactions to open payment channels.
With regard to Nano, I was happy to see a different approach to the same problem that was more intuitive. I run a small business and am waiting for the desktop and mobile wallets to come out of beta before I offer the ability to pay with Nano.
I'd be happy if something came along that was better than Nano. I have it on my todo list to look into Byteball Bytes. I am optimistic about larger scale benefits that society will enjoy from the cryptocurrency space if certain projects are successful (eg improved ease of financial auditing, information-sharing platforms with strongly reduced odds of astroturfing, disappearance of credit card fees, increased financial transparency, reduced exchange fees when traveling, banking for the unbanked, etc). Since I am optimistic about the societal benefits from the space as a whole, I want to see more developers interested in getting involved.
It's a weird space. I see the general concept behind cryptocurrencies as bringing the same benefits you've outlined and from a technology and software perspective these projects are fascinating.
My contention with most of these projects and users is that in these specific implementations nearly every single one of the cryptocoin projects are designed to enable oligarchical wealth extraction from downstream investors - especially in the case of uninformed users/speculators who join the network later.
The question becomes of sustainability - if there's no underlying value to the asset and it relies on speculation and the supply is heavily centralized among a small pool of early adopters than there will likely be a point where buy pressure runs dry and most of the late adopters will be unable to exchange the same amount of wealth they traded into the system.
Rearding usenano.org, you have to keep in mind that adaption barely started like 4 months ago after the distribution ended.
You get access to Nano like with every other currency, work to receive a bit of it or exchange it with another currency.
Old users can simply horde the supply, do nothing, and wash trade to manipulate the spot price.
Classic penny stock scam.
In light of the downvotes with no response, here is some reasoning. He bought in at around $30, and the first thing he did was clone BTC with minor negligible modifications. Philosophically at that time, this shows a remarkable lack of commitment to the underlying goal. Then, during the recent boom he completely cashes out of his own project while the market cap shows nothing close to the transformative goal of the creation of Bitcoin. Ultimately what he does doesn't matter, but his actions speak louder than words. In addition, the tactics employed within Coinbase for the LTC listing and his involvement in a proof of stake coin leave me completely unsurprised. This isn't to say Nano has no merit, I congratulate the team there, but proof of stake, unfortunately, results in all rewards to creators and an unsatisfying amount of control among people where distribution was guaranteed for no "work".
You think Bitcoin is good but fear Litecoin for creating a new alternative system?
You think deregulating into a anarcho-capitalist deflationary market is good, but then complain when someone does something you don't agree with?
but proof of stake, unfortunately, results in all rewards
to creators and an unsatisfying amount of control among
people where distribution was guaranteed for no "work".
Your other crticism of maximalists fearing an alternative, this is really just BS. I will gladly tell you (as many maximalists will) that Monero is actually better on most fronts that Bitcoin tries to win on. Scalability is really the only thing it leads on, and this is not out of the realms of possibility for Monero. So you can choose your oligarchs, and you can choose how they are constrained. Hopefully your community will grow such that you all benefit.
But, that's exactly what happened with segwit. Why is that worth doing but increasing the block size is not?
Because increasing the block size is an inelegant approach that will only work briefly and then there will be more demands to make the blocks bigger again, eventually leading to centralization.
Increasing the block size doesn't solve the problem, it just makes the problem bigger.
other "coins" with larger faster block sizes are already running into storage issues.
see: https://en.wikipedia.org/wiki/Induced_demand
edit: what's up with the downvotes? i'm providing a name to the phenomena and providing a wikipedia link to it.
Maybe because you provided a link without summarizing it?
(Just guessing — I thought your comment was sufficient, and I upvoted it. Also — I know it's policy not to discuss votes, but I'm also a fan of feedback loops that lead to desired behavior, and I don't see enough signal in this one.)
Because having a bigger block size raises the barrier to being a miner. (CapEx and OpEx are both greater.)
Imagine the other extreme: mining is so cheap that every phone, watch, and — oh let's just throw in every mouse and pigeon cortex — can be a miner. This is near one extreme of decentralization.
That's unattainable[1], but it's an intuition hook for the fact that the more expensive you make mining, the more centralized it becomes.
[1] IOTA tries to get closer to this. It makes a couple of changes from Bitcoin / Ethereum / etc. (1) IOTA uses a graph instead of a chain — this is why mining is cheaper, and low-powered IOT devices can mine. (2) IOTA uses homegrown cryptography, (EDIT: that has been proven exploitable multiple times), instead of reviewed standards. (2) isn't necessary for (1), nor does it help decentralization; it just seems to be an attached vanity project.
Yeah, I probably didn't emphasize this enough. In addition to last year's curl fiasco[1], and this year's email dump[2], there's now this unlucky-13 exploit[3].
> no IOT company will ever bother with it
This would seem to follow, but [4] (partnership with Cisco, Samsung, and Volkswagen), if true, contradicts it. (I'm skeptical of IOTA partnership announcements because of last year's IOTA/Microsoft “partnership”[5].)
[1] https://hackernoon.com/why-i-find-iota-deeply-alarming-934f1...
[2] https://spectrum.ieee.org/tech-talk/computing/networks/crypt...
[3] http://blog.lekkertech.net/blog/2018/03/07/iota-signatures/
[4] https://www.computerworld.com.au/article/630565/blockchain-n...
[5] https://cointelegraph.com/news/iota-clarifies-misleading-mic...
[1] https://www.investopedia.com/news/sites-are-using-your-brows...
Repeating this propaganda over and over and over doesn't make it true.
No centralization will occur with an increase in block size, as there will still be enough participants to prevent attacking the block chain.
If what is meant by centralization is the reduction of people who can run nodes, then keeping the block size small also increases centralization by this definition, as there is a reduction in people who can afford to transact on the main chain.
But when it comes to maintaining the core trustless network inherent in the bit coin algorithm, increasing block size does nothing to break its function.
Stop with the propaganda.
It completely breaks the fundamental and original usecase of bitcoin: peer to peer electronic cash.
Now it's "first world speculator to first world speculator through intermediary financial institution electronic store-of-value". Doesn't roll of the tongue quite so well, does it?
IMO, XMR and BCH are the current best options for transactions. BTC is being destroyed by people who hadn't even heard of it 5 years ago.
There is no requirement for this. This is FUD.
So like I don't mind if we end up that you need at least $1million to become a miner, hell we are half way there anyway on both chains, I just mind if nobody can join, or if it goes to $1billion to be able to mine.
LN seems like the ultimate in centralisation so as an alternative (while it might work,) it's a far inferior solution on that score.
Even Satoshi was convinced that the block limit would be increased (it was only added for ddos protection reasons). He didn't even foresee the "block size debate" as an issue because it was never a debate. Of course the transaction throughput would be increased.
He literally said "Bitcoin never really hits a scaling cap".
Now, I'm not saying we should deify them or assume that they thought of every potential issue. But I think we should be very hesitant to deviate from their vision without an actual justification.
I believe that the community has been poisoned by people who don't even understand the original vision. As soon as Bitcoin Core / Blockstream got involved after Satoshi left the scene, everything went to shit.
Lightning is fundamentally an inferior user experience. You should be able to send money instantly without a third party. THAT was the point of bitcoin. Not to force people through a new type of financial institution (lightning hubs), solely to fix a manufactured fee problem.
Imagine for a minute a future where Bitcoin goes mainstream and needs to process ~2k transactions per second. (A reasonable estimate of the world's current credit card transaction rate, and 3 orders of magnitude more than Bitcoin's current max capacity.) Would that _really_ be possible to sustain just by raising the block size?
Bitcoin's block chain is already 150 GB after only a decade, and if we drastically increase its rate of growth like that (by 3 orders of magnitude) the hardware requirements for even storing the full chain are gonna get ridiculous pretty fast.
That's not to say that I think bigger blocks couldn't work, but I think if Bitcoin does go that route it then it will need to find a way to trim old blocks out of the chain without compromising security in any way. Otherwise there's a real possibility we might end up with a 100 TB chain on our hands within the next 10 years or so. (Assuming Bitcoin succeeds the way we might want it to.)
There are a few on-chain scaling solutions. One is Vitalik's approach to sharding. Payments would be split into debits and credits, and a credit transaction would include a Merkle proof showing that a bunch of validators on a different shard approved the corresponding debit. Double spending would be possible if you can corrupt a single shard, but users would be randomly bounced between shards to make that difficult.
Another solution, which I think is very practical, is to make some protocol changes so that scalable full nodes can be run by a cluster of servers. Running a full node would become expensive, but most users would be fine with SPV clients + fraud proofs. See https://ethresear.ch/t/scaling-via-full-node-clusters/1358
You're correct, of course. But what's wrong with that? You still retain ultimate sovereignty over your funds, which is the most important property, I think. What do you think is lost by Bitcoin being mostly a settlement layer with the option to transact on-chain for a higher fee?
If we adopted a 100mb block size, which is probably pushing the limit of what a normal server machine can handle, that would be just enough for each person to perform two on-chain transactions per year.
Most people would want to settle at least once per month, to collect their paychecks and move the money into a payment channel with a well-connected middleman. That doesn't seem feasible without sharding or some other solution to drastically increase the main chain's capacity.
If I could somehow transfer my employer's IOUs to my landlord off-chain, I figure that break the security model because my landlord wouldn't know if I had double spent the IOUs. Let me know if I'm missing something though.
Your employer will pay you, and then you will pay your landlord. But the only channel you'll have open is one to this 'visa' like entity that sits in the middle, and so will your employer and your landlord. So that trusted intermediary will ensure you don't double-spend to other parties in their channel, but who are the only parties you could double spend to. At least, that is my understanding of how the model works - I haven't read all 59 pages either, though.
The alternative, just fucking sending your bitcoin without a trusted third party, is the only viable option. And that requires not trying to mandate a transaction limit through a completely arbitrary and manufactured block size cap
8000GB drives cost about $150 now. Storage is getting cheaper.
Why not change the PoW hash algo to avoid costly ASICs and help decentralize the more important aspect of blockchain transaction verification?
That's enough to handle the blockchain size increasing by one order of magnitude. I just talked about a scenario where it could conceivably increase by 3.
Storage is indeed cheap, but not _that_ cheap. Unless you're envisioning a scenario where only large stakeholders like miners and exchanges ever have to store a full copy of the blockchain.
Cryptocurrency tx/sec goes up exponentially.
As long as the two rates roughly cancel out, we're okay. If they're massively different rates, then you're still dealing with an exponential which is difficult. Either way though, lightning is a linear benefit, not an exponential one. And it comes at the cost of breaking everything that made bitcoin great in the first place.
I don't ever want to have to deal with an intermediary financial institution again. Somehow, the pro-BTC side of the chain thinks that view is ridiculous.
Like I said, the blockchain is currently ~150 GB. Seems to me it's already overdue for a good pruning.
And if people still _do_ need the full chain, then obviously that solution isn't sufficient to eliminate the problem I outlined in my previous comments.
[1] https://bitcoincore.org/en/meetings/2016/03/10/#initial-bloc...
[2] https://github.com/bitcoincashorg/workgroups/blob/master/wg-...
I'm kinda surprised you consider the dev's rejection of that idea to be "nonsensical". Seems perfectly sensible to me that they wouldn't want to grant that kind of authority to any particular set of individuals. In particular, that method is most certainly _not_ "a trustless way" of distributing the UXTO.
Hopefully whatever solution the BCH devs are working on isn't anything like that...
actually, 2.7G https://statoshi.info/dashboard/db/unspent-transaction-outpu...
Along that analogy, LN is more like carpooling. More commuters, same number of cars, no changes required to the roads. It's a cheaper upgrade that achieves the same effect in a different way.
Also, high fees (which blockstream vocally is in favor of) increase UTXO bloat by preventing consolidation
Also, when the bulk of transactions moves to Lightning, the mainnet fees will become much lower.
Remember that at least one of these blocks is generated every 10 minutes, and more than one might be flying around during a chain split. Remember also that nodes do actually need to iterate over all the transactions in the block to check they are valid when they receive a new block. Proof of stake prevents malicious actors from wasting CPU/DiskIO on full nodes with spam attacks, but the transactions in a block with PoS signature still need to be validated, ideally before the next block arrives.
Originally with the 1MB block, there were quite a lot of full bitcoin nodes running on raspberry PI's under peoples desks in places with really shitty internet. Segwit kinda-sorta actually increased the block size from 1MB to up to 4MB. 16% of Malaysia gets internet slower than 256kbps. Running a bitcoin node today takes up ~20% of a connections total bandwidth in these places. Increase the block size to 20MB, and it will not be possible to run a node in some areas of Malaysia, because 20MB/10min is too fast for the connection.
At 20MB of transactions per 10 minutes it's also possible that the diskIO on a gen-1 Raspberry PI using a cheap SD card might not be enough to scan and validate every transaction in an incoming block. Remember that a node might have to scan very far back in the blockchain to find the last time an unspent output was interacted with. I'm not sure how big a block has to be before that IO overhead starts eliminating entry-level hardware.
But you don't actually get much for increasing to 20MB blocks. Another poster said that bcash going from 1MB to 8MB blocks increased the throughput from 7tx/s to 62tx/s. Lets take that as gospel, assuming that's 1MB blocks vs 8MB blocks, and extrapolate like madmen. To get to that posters desired 7,000tx/s "Visa scale", we'd need blocks of around...1GB.
That's 13.3mbps 24/7. Now most of Australia and the USA can't host a full node, and that's before we start talking not just about disk IO but even hard drive space. If new blocks are being created at the rate of 1 Gigabyte per 10 minutes, you'll need to provision 4 terabytes of new storage every month to compete with Visa.
Look, short version is this: scaling by increasing the block size eventually ends in performance requirements that force datacenter scale hardware requirements. If bcash ever reaches that point, it will have lost the decentralized, censorship resistant attributes that make cryptocurrencies valuable in the first. If your cryptocurrency isn't decentralized, you might as well use a bank. There's better regulation and much less uncertainty in being a customer of a bank.
So anyway, the Lightning network developers think that LN provides a better scaling solution. Maybe they're right. If they're not, someone will try something else. Maybe there's no solution that can scale to Visa scale, we just don't know. But bigger blocks is definitely not that solution.
>But bigger blocks is definitely not that solution.
How easy it is to make a claim without any proof.
>Originally with the 1MB block, there were quite a lot of full bitcoin nodes running on raspberry PI's under peoples desks in places with really shitty internet. Segwit kinda-sorta actually increased the block size from 1MB to up to 4MB. 16% of Malaysia gets internet slower than 256kbps. Running a bitcoin node today takes up ~20% of a connections total bandwidth in these places. Increase the block size to 20MB, and it will not be possible to run a node in some areas of Malaysia, because 20MB/10min is too fast for the connection.
Heh, even Segwit proponents don't understand Segwit. Please stop lying about 4MB blocks, it just wastes all of our time. Segwit arbitrarily considers the "witness" portion of the TX to be 25% of its real size in bytes (they define a "block weight" accounting measure that distorts the true storage cost).
This means blocks can only be 4MB if the block is entirely witness data, which never happens in the real world. In practice, segwit will give you 1.7-2MB blocks. There is no efficiency increase (in terms of tx thruput per unit of computation, etc) with Segwit at all, there is only the increased tx thruput caused by bigger blocks (how ironic).
>Running a bitcoin node today takes up ~20% of a connections total bandwidth in these places. Increase the block size to 20MB, and it will not be possible to run a node in some areas of Malaysia, because 20MB/10min is too fast for the connection.
You use a misleading definition of bitcoin nodes that has been used to poison the discussion. A non-mining node has no role in securing the network, except for SPV wallets (lite wallets). Mining nodes have the full power to choose which transactions are uptaken into the blockchain (merkle tree), so non-mining nodes are a garbage metric to use to judge 'centralization'. It doesn't matter if everyone and their dog has a copy of the blockchain on their raspberry pi, if they're not mining they're not securing the network, period.
The original bitcoin whitepaper written by Satoshi is quite clear - when they refer to nodes, they mean miners.
As you can see, the entire manufactured block size debate is built on misinformation and propaganda. How sad that the bitcoin community fell apart as soon as Satoshi disappeared.
>At 20MB of transactions per 10 minutes it's also possible that the diskIO on a gen-1 Raspberry PI using a cheap SD card might not be enough to scan and validate every transaction in an incoming block. Remember that a node might have to scan very far back in the blockchain to find the last time an unspent output was interacted with. I'm not sure how big a block has to be before that IO overhead starts eliminating entry-level hardware.
Entirely irrelevant. Your average cryptocurrency user does not need to validate the entire blockchain. They only need to ensure their own TX have made it into the chain, a role fulfilled by SPV wallets like electrum. Again, Satoshi himself said this.
There is nothing on the horizon that suggests a 4TB/month growth rate will be serviceable by anything less than data-center grade hardware at any point in the next 10 years. Beyond then, it's a crapshoot.
I'd /like/ to see bitcoin operate at Visa scales before then, so I must look for a solution that can work with a reasonable extrapolation of the state of storage today.
Never the less, I sense that you have an agenda and that you will not be dissuaded from it. Continue to preach as you see fit. Before I head off, I'll say the following: I'm lightly invested in bitcoin, litecoin and vertcoin, with perhaps $150USD spread across the three. I have no investment in bitcoin cash.
Care to share your crypto investment portfolio with our fellow comment-readers?
Once BTC fees hit $40 average tx (I paid $100 due to UTXOs increasing my tx size in bytes because I actually used bitcoin to transact), I had to accept that BTC was done.
I just noticed this snippet, and it's wrong enough that I feel I should address it separately. Safe to say you don't understand blockchain verification very well.
https://bitcoin.org/en/bitcoin-core/features/validation
https://bitcoin.stackexchange.com/questions/54697/transactio...
Why would any non-mining node choose to assume that the mining nodes are non-malicious when they could just check? That's pretty much the whole point of the distributed ledger concept: not having to trust anyone else on the network, yet still being able to transact.
Gavin Andresen actually has a decent summary of some of different "O(n^2)" arguments on his blog http://gavinandresen.ninja/are-bigger-blocks-dangerous though I disagree with most of his conclusions.
Regarding all of these, they may not be literally O(n^2) but they are certainly more than O(n) and they compound each other.
His argument I disagree with most is the Metcalfe's Law one:
> I’ve transacted with probably under 100 other people or companies in the five years I’ve been using Bitcoin; the demand for transactions scales up linearly with the number of people using it.
As more people use Bitcoin then Gavin's personal demand for transactions would increase roughly linearly, but because there are more users the overall demand would increase quadratically.
Or is he saying his transaction volume wouldn't increase even as more people accepted Bitcoin? I don't believe that.