Chapter 05 · The Bitcoin breakthrough

Halving: the hardness hard-coded into the protocol

9 min
You are joining a course midway

This chapter builds on the ones before it. You can read it now, but it will not count towards your progress until the earlier chapters are done.

Block
# block 0001

In 2009, mining a block paid out 50 bitcoins. In 2026, it pays 3.125. By 2140, it will pay zero. This isn't drift, it's been the plan from day one.

You've already met in the previous chapter. It rests on serious effort from miners.

# block 0002

Why bother? Not out of pure altruism. The protocol rewards them.

# block 0003

But the subsidy doesn't stay put. Look carefully at the curve below.

Block reward (BTC) - halving schedule
Each plateau corresponds to a halving (~every 210,000 blocks, i.e. ~4 years).

The subsidy only shrinks over time. The last fraction of a bitcoin will be issued around 2140.

The issuance of new bitcoins follows a mathematical staircase. It's driven by a mechanism called the halving. Let's take a closer look.

# block 0004
Enough theory. Pull the lever below and travel through time to see what it actually looks like.
Halving time machine

Set the dial. Pull the lever. Discover the block reward of that era.

Year2026

Pull the lever to travel through time.

Destination year2026
Rewards rounded to the nearest satoshi. Beyond ~2140, issuance drops to zero.
# block 0005

Bitcoin gets scarcer for everyone, and tougher for those who produce it.

Put yourself in a miner's shoes for a moment.

  • your bitcoin income just got halved
  • your costs (hardware, electricity) barely budge

Your margin is under threat. You might walk away from the market, along with other miners who can no longer keep up. And right there, the network's security could start to wobble.

How would you answer the following question?

Quiz

After a halving, what keeps the network in balance?

# block 0006

One question keeps coming back about the long-term economics of mining, once new bitcoin issuance has nearly dried up.

# block 0007

Bitcoin flips the standard monetary logic on its head:

  • In classical monetary systems, the cost of the system is largely paid through money creation and intermediaries
  • In Bitcoin, the cost is paid through the fees users agree to when they use the network

A virtuous cycle that feeds itself.

Here's the idea in motion (illustrative figures, 2025 ballpark):

Network usage300 tx/min
Fees generated (per block)0.05 BTC
Miner revenue (per block)3.175 BTC
Network security200 EH/s
Value secured€200B
Increase usage to observe how the cycle propagates.
# block 0008

What exactly are they securing?

How does a Bitcoin transaction work without a bank? And how does ownership change hands without an intermediary?

On to the next chapter: .

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