Physical Limitations of OOPS

• OOPS should scale in unbeatable fashion. Limits?

• Resets all states; so we may use reversible computing (Bennett, 1982): no fundamental heating problems expected.

• Computing power by cost grows 1000-fold per decade (Moore)

• Bremermann limit: 1051 operations per second on 1032 bits for Lloyd’s (2000) ultimate laptop (1kg, 1l).

• Sun-sized OOPS (1030 kg): given previous solutions, will find solutions to new problems requiring 200 bit programs running for, say, 1020 steps.

• 300 bits would already be too much: light speed limits acquisition of additional mass through function quadratic in time.

• But even modest speedup factor 109 expected until 2030 very promising (e.g., we could quickly solve 20 disk Hanoi without intermediate tasks).

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