• Delaya – Shapiro Time Delay physics T-shirt
  • Delaya – Shapiro Time Delay physics T-shirt
  • Delaya – Shapiro Time Delay physics T-shirt
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DelayaShapiro Time Delay

Delaya – Shapiro Time Delay Physics T-Shirt

$29.99 USD
$29.99 USD
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Can the Sun make a signal late? Delaya carries a radar pulse from Earth to Venus and back, grazing the Sun. In curved spacetime the echo takes longer, by up to about 200 microseconds near superior conjunction. Irwin Shapiro proposed this “fourth test” of general relativity in 1964, and radar echoes later confirmed it. 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

Bounce radar off Venus when it sits behind the Sun and the echo comes back late, by up to about 200 microseconds.

Irwin Shapiro predicted this in 1964 as a fourth test of general relativity: near a mass, light takes longer to cross curved spacetime. The delay grows with the Sun's mass and with how close the signal grazes it.

The radar experiments confirmed it, and the Cassini spacecraft pinned it to about one part in 100,000 in 2003. Delaya isn't slow. The sun made her late.

Equations

\[\Delta t \approx \frac{4GM_\odot}{c^{3}}\,\ln\!\left(\frac{4\,r_E\,r_P}{b^{2}}\right)\]
SymbolMeaningUnit
\(\Delta t\) extra round-trip travel time of a radar pulse passing the Sun \(\mathrm{s}\)
\(G\) gravitational constant \(\mathrm{m^3 kg^{-1} s^{-2}}\)
\(M_\odot\) mass of the Sun \(\mathrm{kg}\)
\(c\) speed of light \(\mathrm{m/s}\)
\(r_E, r_P\) distances of Earth and of the planet from the Sun \(\mathrm{m}\)
\(b\) closest approach of the signal to the Sun's centre \(\mathrm{m}\)

Sources

  1. Shapiro (1964) Fourth Test of General Relativity, Phys. Rev. Lett. 13, 789
  2. Bertotti, Iess & Tortora (2003) A test of general relativity using radio links with the Cassini spacecraft, Nature 425, 374
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