Boundraith, the Mismatched Border Wraith Mug
Kapitza resistance: heat crossing a solid–liquid-helium boundary meets a thermal boundary resistance RK ∝ T⁻³ (acoustic mismatch).
The joke: Phonons mismatch at interfaces; cryo people sinter silver to fight it. Distinct from KAPITZADIRAC (live sticker). The slogan on the mug reads EVEN HEAT HESITATES AT THE BOUNDARY.
Source: P. L. Kapitza, J. Phys. USSR 4, 181 (1941); G. L. Pollack, Rev. Mod. Phys. 41, 48 (1969).
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 |
|---|---|---|
| \(R_K\) | Kapitza (thermal boundary) resistance | \(\mathrm{K·m^2/W}\) |
| \(T\) | temperature | \(\mathrm{K}\) |
Sources
- P. L. Kapitza, J. Phys. USSR 4, 181 (1941)
- G. L. Pollack, Rev. Mod. Phys. 41, 48 (1969) (opens in a new tab)
Field notes
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