• Dragmaw – Frame Dragging physics T-shirt
  • Dragmaw – Frame Dragging physics T-shirt
  • Dragmaw – Frame Dragging physics T-shirt
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DragmawFrame Dragging (Lense–Thirring)

Dragmaw – Frame Dragging (Lense–Thirring) Physics T-Shirt

$29.99 USD
$29.99 USD
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Color
White · Black
Size
S–5XL
Made
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Does a spinning planet drag space with it? General relativity says yes: a rotating mass twists nearby spacetime, so a gyroscope in orbit slowly turns. Around Earth the effect is tiny. Gravity Probe B measured 37.2 ± 7.2 milliarcseconds per year, against a prediction of 39.2. Dragmaw is that spinning mass. Pixel-art unisex tee; equation, symbols and sources in the physics panel below.

Color
Size

Size guideS–5XL · inches

Details

Size & fitS–5XL

Unisex heavy cotton (Gildan 5000), classic fit.

SizeWidthLengthSleeve
S182815.1
M202916.5
L223018
XL243119.5
2XL263221
3XL283322.4
4XL303423.7
5XL323525

Measurements in inches, ±1.5 in tolerance.

ShippingFree US

Free US shipping · $10 flat shipping outside the US. Printed to order for you.

Delivery times & where we ship

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.

Full refund & replacement policy

The physics

A spinning mass drags spacetime round with it. Josef Lense and Hans Thirring worked out the effect from Einstein's equations in 1918.

Near Earth it is tiny. Gravity Probe B flew four near-perfect gyroscopes in polar orbit, and in 2011 reported a frame-dragging drift of 37 ± 7 milliarcseconds a year, against a prediction of 39.

Near a spinning black hole it is strong enough that nothing can stay still. Dragmaw spins, and space spins with him.

Equations

\[\boldsymbol{\Omega}_{\text{LT}} = \frac{G}{c^{2} r^{3}}\left[\,3\,(\mathbf{J}\cdot\hat{\mathbf{r}})\,\hat{\mathbf{r}} - \mathbf{J}\,\right]\]
SymbolMeaningUnit
\(\boldsymbol{\Omega}_{\text{LT}}\) frame-dragging (Lense–Thirring) precession rate of a gyroscope \(\mathrm{rad/s}\)
\(G\) gravitational constant \(\mathrm{m^3 kg^{-1} s^{-2}}\)
\(c\) speed of light \(\mathrm{m/s}\)
\(r, \hat{\mathbf{r}}\) distance from the body's centre and the unit vector to the gyroscope \(\mathrm{m, –}\)
\(\mathbf{J}\) angular momentum of the rotating body \(\mathrm{kg m^2/s}\)

Sources

  1. Everitt et al. (2011) Gravity Probe B: Final Results of a Space Experiment to Test General Relativity, Phys. Rev. Lett. 106, 221101
  2. Lense & Thirring (1918) Über den Einfluß der Eigenrotation der Zentralkörper auf die Bewegung der Planeten und Monde nach der Einsteinschen Gravitationstheorie, Phys. Z. 19, 156 (citation only)
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