Although the building blocks of life such as hydrogen and oxygen appear stable to us, many theories of physics predict that they are actually just tremendously long-lived, with the particles found in their nuclei slowly, but ultimately decaying.

To investigate this idea, researchers have been hunting for evidence of this decay by looking for faint signals of decaying protons in Japan’s Super-Kamiokande observatory.

So far, no definitive signals of proton decay have emerged, implying that if the proton does decay, it probably has a lifetime exceeding 10³³ years—that’s 10 with 32 zeros behind it.