The rates of graviton emission and absorption by hydrogen atoms have been calculated. The absorption rate is proportional to the number of atoms and the graviton luminosity. Interstellar and intergalactic hydrogen is abundant, and the graviton luminosity of the Sun and typical stars (eV–keV) overlaps with hydrogen’s resonant frequencies, enabling a method to measure the graviton luminosity of different regions. The method relies on the ratio of photon luminosities from interstellar hydrogen, which reveals the helicity difference: 1 for photons vs. 2 for gravitons. This ratio is sensitive to sources of gravitational radiation and provides a way to estimate their intensity, addressing the lack of observational data.
Hydrogen is the most common element. Its atoms are like antennas: they emit and absorb light at very specific frequencies. Einstein predicted that spacetime can ripple—these are gravitational waves. It turns out, clouds of hydrogen can also capture them: the energy of gravitons from ordinary stars precisely matches the resonance of hydrogen atoms. An atom that gains energy releases it either as light or as a gravitational wave. By comparing a cloud's glow with expectations, scientists calculate the fraction that went into gravity. This way, we can detect gravitational tremors from any objects—from individual stars to black hole mergers—and build a gravitational map of the Universe.
🎯 Gravitons twist spacetime twice as much as photons, which is why gravitational waves interact so weakly with matter.
🎬 In the film 'Interstellar', the characters communicate via gravity. The new method shows that we can pick up the gravitational whispers of distant stars using ordinary hydrogen.