Reversa
Loschmidt's Reversal Paradox Physics
Size guide S–5XL · inches
Reversa flips every molecule's velocity, and the gas should un-mix. So why does time only run one way?
The Physics
Newton's laws run equally well backwards, yet Boltzmann's H-theorem says a gas always heads toward equilibrium. Reverse every velocity and the gas would retrace its steps, so the arrow of time cannot come from the dynamics alone. The H-theorem rests on the molecular-chaos assumption.
H = ∫ f ln f d³v, dH/dt ≤ 0
- H: Boltzmann's H function (dimensionless, per volume)
- f: velocity distribution (s³/m⁶)
- d³v: velocity-space volume element (m³/s³)
- t: time (s)
Josef Loschmidt raised the objection in 1876.
Honest caveat: This does not break the second law. Why the past had low entropy is still debated.
On the shirt
Front: Reversa, the pixel-art character, with the title. Back: the reversibility of Newton's laws, Boltzmann's H-theorem, the molecular-chaos note and the 1876 objection. Printed on a unisex tee.
Shipping calculated at checkout by destinationMade to order, ships in 2–5 business days
Details
Size & fitS–5XL
Unisex heavy cotton (Gildan 5000), classic fit.
| Size | Width | Length | Sleeve |
|---|---|---|---|
| S | 18 | 28 | 15.1 |
| M | 20 | 29 | 16.5 |
| L | 22 | 30 | 18 |
| XL | 24 | 31 | 19.5 |
| 2XL | 26 | 32 | 21 |
| 3XL | 28 | 33 | 22.4 |
| 4XL | 30 | 34 | 23.7 |
| 5XL | 32 | 35 | 25 |
參考尺度：M 碼寬 20 in（50.80 cm），約為 3.143 × 1034 個普朗克長度（lP = 1.616255 × 10−35 m）。用捲尺量更快。
Measurements in inches, ±1.5 in tolerance.
ShippingBy destination
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Returns & replacements21 days
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Field notes
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