Kilonova
GW170817 Neutron Star Merger Physics
Size guide S–5XL · inches
Two neutron-star dancers collide in a burst that rains gold. Gravity and light set off together and arrived neck and neck.
The Physics
On 17 Aug 2017 LIGO and Virgo detected gravitational waves from two neutron stars merging about 40 Mpc away. 1.74 ± 0.05 s later, gamma-ray burst GRB 170817A arrived. After a journey of about 130 million years, that tiny gap pins the speed of gravitational waves to the speed of light.
−3 × 10⁻¹⁵ ≤ (v_gw − c)/c ≤ +7 × 10⁻¹⁶
- v_gw: gravitational-wave speed (m/s)
- c: speed of light (m/s)
- 𝓜: chirp mass (kg), measured as 1.188 (+0.004/−0.002) solar masses
The signal arrived on 17 Aug 2017 at 12:41:04 UTC, and multi-messenger astronomy began.
Honest caveat: The 1.74 s gap includes the delay in emitting the gamma rays, which did not leave at the same instant.
On the shirt
Front: Kilonova, the pixel-art character, with the title. Back: the timeline, the speed bound, the chirp mass formula and the start of multi-messenger astronomy. 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 |
For scale: size M is 20 in (50.80 cm) wide, about 3.143 × 1034 Planck lengths (lP = 1.616255 × 10−35 m). A tape measure is quicker.
Measurements in inches, ±1.5 in tolerance.
ShippingBy destination
Shipping calculated at checkout by destination. Printed to order for you.
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.
Field notes
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