Avergail, the Mean-Field Courtier Mug
Mean-field (Weiss) theory replaces neighbours by their average field; it fails near critical points where fluctuations dominate.
The joke: Mean field ignores fluctuations, which is why it fails in the heated Q&A. The slogan on the mug reads MEAN FIELD: I FEEL THE ROOM'S AVERAGE.
Source: P. Weiss, J. Phys. Théor. Appl. 6, 661 (1907).
Shipping calculated at checkout by destinationMade to order, ships in ~10 days
Details
Size & material11oz · 15oz
Black glossy ceramic mug with a C-handle. Lead- and BPA-free.
- 11oz: 0.33 l
- 15oz: 0.44 l
CareDishwasher & microwave safe
Dishwasher safe (top rack) or hand wash. Microwave safe.
ShippingBy destination
Shipping calculated at checkout by destination.
Made to order: about 10 days of production and handling before it ships.
Returns & replacements21 days
Every item is printed to order, so we can’t accept returns or exchanges for change of mind, or if you ordered the wrong size or colour.
Print defect, misprint, damage or the wrong item? We’ll send a free replacement, or a refund if you prefer. Report it within 21 days of delivery with a photo; no need to send it back.
The physics
Equations
| Symbol | Meaning | Unit |
|---|---|---|
| \(B_{\text{eff}}\) | effective (Weiss mean) field | \(\mathrm{T}\) |
| \(B\) | applied field | \(\mathrm{T}\) |
| \(\lambda\) | molecular-field constant | \(\mathrm{T·m/A}\) |
| \(M\) | magnetisation | \(\mathrm{A/m}\) |
| \(\chi\) | magnetic susceptibility (T > T_c) | — |
| \(C\) | Curie constant | \(\mathrm{K}\) |
| \(T\) | temperature | \(\mathrm{K}\) |
| \(T_c\) | Curie temperature | \(\mathrm{K}\) |
Field notes
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