Bitcoin Q&A: The value of proof-of-work

Can a blockchain exist without miners, proof-of-work, or blocks? What are the implications for security, trustlessness, and decentralisation? Not all distributed ledgers are blockchains. What is the influence of alternative energy generation on mining in proof-of-work cryptocurrencies? Should we use alternative algorithms that generate “useful work” in addition to mining cryptocurrencies? The hard promises that Bitcoin provides are valuable and useful in themselves. What is the difference between proof-of-work and proof-of-stake?

Note: These sessions were recorded live using Google Hangouts. The audio and video may be slightly out of sync at some points.

These questions are from the MOOC sessions 7.2 and 8.2, covering the Byzantine Generals’ Problem, which took place on February 26th 2017 and September 15th 2017 respectively. Andreas is a teaching fellow with the University of Nicosia. The first course in their Master of Science in Digital Currency degree, DFIN-511: Introduction to Digital Currencies, is offered for free as an open enrollment MOOC course to anyone interested in learning about the fundamental principles.

If you want early-access to talks and a chance to participate in the monthly live Q&As with Andreas, become a patron:

Immutability and Proof-of-Work: The Planetary Scale Digital Monument –
Consensus Algorithms, Blockchain Technology, and Bitcoin –
Advanced Bitcoin Scripting Part 1: Transactions and Multisig –
Advanced Bitcoin Scripting Part 2: SegWit, Consensus, and Trustware –
What is Consensus: Rules without Rulers –
Forkology: A Study of Forks for Newbies –
Bitcoin: Where the Laws of Mathematics Prevail –
The rules of Bitcoin (part 1) –
The rules of Bitcoin (part 2) –
Decentralized power, leaderless governance –
Proof-of-Work (PoW), Proof-of-Stake (PoS), Delegated Proof-of-Stake (DPoS) –
Does the Lightning Network have proof-of-stake elements? –
Directed acyclic graphs (DAGs) and IOTA –
Intrinsic vs. extrinsic assets –
Scaling, trust, and trade-offs –
Why running a node is important –
Running nodes and payment channels –
What happens during a fork? –
SegWit adoption –
Energy consumption –
Solar energy and mining in space –

Andreas M. Antonopoulos is a technologist and serial entrepreneur who has become one of the most well-known and respected figures in bitcoin.

Follow on Twitter: @aantonop

He is the author of two books: “Mastering Bitcoin,” published by O’Reilly Media and considered the best technical guide to bitcoin; “The Internet of Money,” a book about why bitcoin matters.





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Music: “Unbounded” by Orfan (
Outro Graphics: Phneep (
Outro Art: Rock Barcellos (

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Written by lena

Foodie, Performer, Water Protector, Avid Baker, Syndicate Aggregator. I probably still live in my mom's basement.


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  1. Thank you for another well done explanation. Newcomers that want to replace PoW need to understand the implications.

  2. tell us what is stoping hardware wallet from using zcash zaddress and monero and other popular privacy coins….

  3. Remember that surplus energy can be stored, e.g. by pumping water up into lakes, from where it can be used again at any later time. In Europe it even happened that nuclear energy was used to do that, and then the energy was sold as green, since it came from a lake 🙂

  4. Mr. Antonopoulos, did you have a chance to see what hashgraph is doing? can Hashgraph become a competitor of Bitcoin block chain ?

  5. When you use Miner to generate usable Heat Mining is a costless waste Product. You can do it all over the World and make Mining decentralized. To wate the heat is maximal dumb.

  6. What is the effect of merged mining with bitcoin? I have seen a few references on reddit about how Elastos, which will begin merge mining with bitcoin in december, will benefit.

  7. Rewards are not needed, running a Delegated Proof of Stake node cost about nothing, NANO is a good example, there's no rewards but still thousands of representatives and they are happy to do it to get "trust votes" and for the network. Rewards lead to corruption and centralization.

  8. Andreas, one more thing: once you said "regulation of the protocol itself is not possible at this time" to Australian Senate… that scared me! Were you avoiding them to know that is not possible or is it possible and may happen after all?!?!?

  9. What are some genuinely good business solutions people can implement to add value to the Bitcoin Network? Can you go over different business solutions for different countries?

  10. Also, I am very thankful you only called coal dirty and not nuclear power 🙂 molten salt reactors for the win

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