The Machine and the Question
2
What Entropy Is
The Alan Machine
Preface
The Machine and the Question
1
Meet Alan
2
What Entropy Is
3
The Arrow of Time
Interlude: Does Time Flow?
Information Is Physical
4
Maxwell’s Demon and the Szilard Engine
5
Landauer’s Principle
6
Reversible Computing
7
Can a Mind Beat the Second Law?
Interlude: Three Demons
The Limits of the Machine
8
How Fast Can It Compute
9
How Much Can It Hold
10
Is Alan a Quantum Computer?
11
Laplace’s Demon
12
Black Holes and Information
Interlude: Are We Inside an Alan?
Reversing Entropy
13
Local Reversal
14
Life: The Original Local Reversal
15
Fluctuations and Recurrence
16
Global Reversal
Interlude: Would You Remember?
The Impact on Time
17
What Time Is
18
Would Time Run Backward
19
Closed Timelike Curves
20
The End of the Universe
Interlude: Can Alan Think?
Epilogue: What Alan Cannot Do
Building Alan
About Building Alan
CMOS: The Baseline
The Cost of Moving Data
Getting the Heat Out
Adiabatic and Reversible Logic
Superconducting Logic
Quantum Hardware
Thermodynamic and Probabilistic Computing
Neuromorphic Computing
Optical Computing
The Energy of a Token
Papers
About the Papers
References
Contributing
Appendices
A
Concepts
B
Notation
C
Constants
D
A Short Primer on Statistical Mechanics
E
Moderators and Curators
The Machine and the Question
2
What Entropy Is
2
What Entropy Is
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1
Meet Alan
3
The Arrow of Time