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Graviton Whisper

Quantum Gravity / Force Carrier Physics

\[\Box\,\bar h_{\mu\nu} = -\frac{16\pi G}{c^{4}}\,T_{\mu\nu}\]
$29.99 USD
$29.99 USD
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Size guide S–5XL · inches

Meet Graviton Whisper. Gravitational waves are real. Their quanta may be too. LIGO caught spacetime ripples from merging black holes in 2015. If gravity is quantum, those waves come as gravitons: massless, spin 2, energy hf; observations already cap any graviton mass at 1.27×10⁻²³ eV/c². None has ever been detected, and catching a single one may be beyond any practical detector. Graviton Whisper on a pixel-art unisex tee; equation, symbols and sources in the panel below.

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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

För skalans skull: storlek M är 20 in (50.80 cm) bred, ungefär 3.143 × 1034 Plancklängder (lP = 1.616255 × 10−35 m). Ett måttband går snabbare.

Measurements in inches, ±1.5 in tolerance.

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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.

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The physics

Far from strong sources, Einstein's equations reduce to a wave equation: moving masses send out ripples in spacetime that travel at the speed of light. A graviton would be the quantum of those ripples, massless and spin 2, but no single graviton has ever been detected.

Graviton Whisper has never been detected. That is the first and most important fact about them.

Gravity in Einstein's theory is the curvature of spacetime, and ripples in that curvature travel. The first formula on this page is general relativity in its weak-field form: a small wrinkle in spacetime obeys a wave equation, sourced by moving mass and energy. On 14 September 2015 the two LIGO detectors caught one, from two black holes merging over a billion light-years away. The peak strain was about 10⁻²¹, a change in each detector's four-kilometre arms of a small fraction of a proton's width. In the merger, about three solar masses' worth of energy left as gravitational waves. In 2017 a neutron-star merger was seen in both gravitational waves and gamma rays, and the two arrived within seconds of each other after travelling 130 million years: gravity's waves move at the speed of light to about one part in a thousand trillion.

Gravitational waves are classical, observed facts. The graviton is the hypothetical next step. Electromagnetic waves come in quanta: light comes as photons. If gravity is quantum too, its waves should come as gravitons, and the second line says what they would be like: massless, with energy h times frequency, and spin 2, because the field they ripple is a tensor rather than a vector. Observations already limit how heavy a graviton could be: a massive graviton would make gravitational waves of different frequencies travel at different speeds, and the LIGO–Virgo–KAGRA catalogue GWTC-3 finds no such effect, setting m_g ≤ 1.27×10⁻²³ eV/c² at 90% credibility, the third line on the back.

Nobody knows how to catch one. Gravity is so weak that detecting a single graviton looks hopeless with any conceivable instrument, and some physicists argue it may be impossible in principle. Whether gravitons exist at all depends on how gravity and quantum mechanics are eventually reconciled, and that remains open.

Graviton Whisper does not bend space; in general relativity, mass and energy do that. If gravitons exist, they would carry the news, one quantum at a time.

Equations

\[\Box\,\bar h_{\mu\nu} = -\frac{16\pi G}{c^{4}}\,T_{\mu\nu}\]
\[E = hf, \qquad m_{g} = 0 \ (\text{if it exists}),\ \ s = 2\]
\[m_g \le 1.27\times10^{-23}\ \mathrm{eV}/c^{2}\quad\text{(LIGO–Virgo–KAGRA, GWTC-3, 90\% credible)}\]
SymbolMeaningUnit
\(\bar h_{\mu\nu}\) trace-reversed metric perturbation \(\mathrm{1}\)
\(\Box\) d’Alembertian wave operator \(\mathrm{m⁻²}\)
\(G\) gravitational constant \(\mathrm{m³·kg⁻¹·s⁻²}\)
\(T_{\mu\nu}\) stress–energy tensor \(\mathrm{J/m³}\)
\(E\) quantum energy \(\mathrm{J}\)
\(h\) Planck constant \(\mathrm{J·s}\)
\(f\) frequency \(\mathrm{Hz}\)
\(m_g\) graviton rest mass (bound quoted in eV/c²) \(\mathrm{kg}\)
\(s\) spin quantum number (angular momentum in units of ħ) \(\mathrm{1}\)

Sources

  1. Encyclopaedia Britannica — Graviton
  2. LIGO/Virgo (2016) Observation of Gravitational Waves from a Binary Black Hole Merger, PRL 116, 061102
  3. NobelPrize.org — The Nobel Prize in Physics 2017 (gravitational waves)
  4. LIGO/Virgo, Fermi, INTEGRAL (2017) Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A, ApJL 848, L13
  5. LIGO–Virgo–KAGRA (2021) Tests of General Relativity with GWTC-3, arXiv:2112.06861

Source Einstein, A. (1916). Näherungsweise Integration der Feldgleichungen der Gravitation. Sitzungsberichte der Königlich Preußischen Akademie der Wissenschaften (Berlin), 688–696.

Field notes

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