Bitcoins biggest flaw

[coinage]

Am I the only one who thinks that the biggest BitCoin flaw is scalability?

When you have at least O(n2) algorithm you can be pretty sure it will bite you in the ass.  Sooner, rather than later.

We have 800 Mb transaction database now. This means that people with slow or traffic-limited internet are out. Mobile devices are out. And it's what – 20 000 users?

Yes, I know you can prune the chain, but to what extent?

When each transaction must be distributed to each member and you have, let's say, a million users, it's roughly one million network packets to send per one transaction.
Each user will do at least one transaction, so it will be one trillion packets!

And a million users? It's nothing. There are 300 million people in US alone.

You get to 100 million users and you will shutdown the Internet  
10 quadrillion packets is a pretty big number. And with more users the number of transactions will grow. And I suspect the growth will be non-linear.

Bitcoin [...] doesn't scale beyond a small town population.

I'm telling you, that idea of an "Internet" will never work if you ever open it up to the masses.  You will someday have hundreds of millions of people all thinking they can establish connections to each other at will, worldwide!  We're not just talking about "E-mail" and "Usenet" nonsense, which are also impossible with too many users, just by themselves.  You will wind up with people on radiotelephones actually expecting to be able to watch videotapes!  It will never scale, can't be done.  It is IMPOSSIBLE.  It is an O(n^2) problem at least.  Forget these silly fantasies.  Just call me when you'd like more text files and I will bring them to you, clear across town, on another state-of-the-art 5.25 inch floppy diskette.  Stay with what works, Alex.  Stay with what works.

[1715267770]

1715267770

[Alex Zee]

Oh, no... I can't survive such amount of sarcasm! My head just exploded!

What have you done?! You... you... killed me....

No, wait. I'm still here.

I admire your faith in technological progress, but comparing it to the Internet is kinda stupid.

You see, on the Internet nobody tries to send every packet to everybody else.

And I don't care, how technologically advanced we are, that won't be possible for a very long time.

[bfever]

I am more concerned with the amount of inter-nodes traffic.

To put it simply - when the number of users is big the block size itself will be too big to be useful.

A block needs to hold 10 minutes of _all_ transactions or the system starts lagging and transaction times will soar to infinity.

Let's assume each user does at least 1 transaction per day. There are 144 blocks per day.
A million users * let's say 100 bytes per transaction / 144 = almost 1 MB per each block = 6 Mb / hour constant incoming traffic to every client.

I love the cryptocurrency idea, but I don't see any ways of implementing it on the scale of PayPal or VISA.

I take your example again of 1 million transactions a day. It doesn't matter how many users send how many, just the total number of transactions per day counts towards the traffic a full client needs to receive to keep up with the block chain.
Let's take 300 bytes per transaction, then we get 300 Mbytes/day of data.

That is 12.5 Mb/hour or 3.5 kb/sec (or about 28kbps), that is about 1/3 of a high quality VOIP connection. Don't see any problems there related to bandwidth !
When we extrapolate on a yearly basis, then we get about 100 Gb/year. Doesn't look much either to store that.

If you add the retransmissions to other nodes: let's assume you're connected to 20 other nodes. Then about 50% of the nodes will already have the data you just received, so you need to transmit about 10x. So now you'll need about 300 kbps. This won't kill the Internet 

So in this regard, the bitcoin protocol has no real "flaw".

[Alex Zee]

Ok, we can somewhat scale to 1 million.

Let's see what will happen at 10.

10 million transactions a day is 3 Gb of data per day. 1 Tb per year.
30 petabytes of total network traffic.

100 million transactions a day is 30 Gb of data per day. 10 Tb per year.
3,000 petabytes of total daily network traffic. Current Internet traffic is about 1,000 petabytes per day,
so this is where we will shutdown the Internet

What about VISA level of 2000 transactions a second? 50 Gb of data per day.

Also, keep in mind that each transaction, as I understand, is sent twice - as an announcement and as a part of a block.

--

Overall, I don't know. Maybe I worry too soon

Maybe by the time it reaches VISA's level, 50-100 Gb per client (or 5,000-10,000 petabytes total) per day wouldn't be a problem...

[skilo]

Regarding the bandwidth issue, I know most ISP are already installing Fios into most of their infrastructure wich is capable of sending  data at the speed of light but i have heard the only bottleneck with Fios is the copper on the customers end.

[andrewbadr]

The transaction rate per person is relatively constant, while technology improves exponentially.

[cbeast]

https://en.bitcoin.it/wiki/Scalability