The second thing you should know is that Krauss isn't directly involved in the experiment he's talking about. That's important, and we'll come back to it later.
2. Wait, what are gravitational waves?
Imagine the universe is a stretchy sheet. When you put something heavy on it (like a bowling ball), the sheet will bend to accommodate the object. And when you place smaller objects into this warped piece of sheet, they'll follow curved paths influenced by the bowling ball. Just picture the way a handful of marbles would act on a stretchy sheet held taut, vs. their behavior on one that was sagging with the weight of a bowling ball.
Space ripples and warps are like that, too, and we call these ripples in spacetime gravitational waves.
There's one obvious way this gravitational wave rumor could have been falsely planted. Because gravitational waves are so tiny, and it's easy to get false positives, the LIGO team includes three individuals capable of injecting false signals to test the group's ability to weed them out. This has happened twice before, and, in one instance, the group was ready to publish the data by the time it was revealed as false. Krauss has said on Twitter and elsewhere that his source knows for sure this isn't a blind-injection test, but that seems unlikely unless he has an in with one of those three researchers.
But that's the thing: No one is confirming these rumors anytime soon. The folks at LIGO haven't responded to our request for comment yet, but they've told other outlets that they won't confirm or deny Krauss's tweet. They're working through their data, which may or may not include evidence of gravitational waves, and they'll release it when they're good and ready. Which brings us to our next point:
4. Is it a good idea to blab about this on Twitter?
Many scientists (including those outside the experiment) seem unamused by Krauss's enthusiasm. “We’ll use something other than the rumor mill when we have a contribution to the discussion," David Shoemaker of MIT told New Scientist.
Indeed, one usually waits to announce a scientific finding after it's been rigorously peer reviewed. When scientists publish their work, they have to let experts outside their group evaluate the data and the findings. By the time something is published in a scientific journal, it's been vetted (though this still doesn't necessarily mean the findings are accurate). Even Krauss told the Guardian that he was only 60 percent certain the finding was real, since he hadn't seen the data for himself.
In an email to The Post, Krauss explained that he'd only tweeted the rumors after seeing that they'd begun circulating in the physics community through other channels.
"I didn’t feel it would jeopardize LIGO, who have no competition and are going to do a careful analysis before saying anything," Krauss wrote. And he said he was surprised that some scientists are peeved about his tweets. "If it turns out to be just a test, then at least the public will have been exposed to the exciting search LIGO is carrying out and why this science is fascinating," he wrote.
But because of Krauss's tweet, the LIGO scientists have lost control of their announcement. Even if they have something that they think is a gravitational wave, they're going to want to be absolutely certain before they even attempt to publish. No one wants to make a claim this monumental and then have it debunked by another scientist – especially because false starts — and this rumor could certainly turn out to be one of those — can confuse the public and make them trust scientists less.