Text of the bet:

"Whereas Carlo Rovelli and Geoff Penington firmly believe that gravity is better
described by a quantum theory.
And whereas Jonathan Oppenheim is more sympathetic to other possibilities (i.e.
doesn’t have a clue),
Oppenheim and Rovelli/Penington accept a wager at 1:5,000 odds
That space-time is described by quantum theory.
This will be determined by any of the following considerations:
1. the creation of entanglement mediated by gravity [1-3]
2. a violation of the decoherence vs diffusion-trade off [4]
3. any other mutually acceptable experimental proposal
4. the discovery of a mutually acceptable UV complete and consistent theory of
gravity
The failure to create gravitationally mediated entanglement is to be regarded as
evidence that space-time is classical. Absent a convincing mechanism from quantum
theory, the direct detection of gravitational diffusion or gravitationally induced
decoherence is evidence pointing towards gravity having classical properties.
Should space-time be shown to be quantum, the loser will give to each of the
winners, one ITEM* of their choice. If the alternative hypothesis is deemed to be
correct, the losers will each give 5,000 ITEMS to the winner.
* ITEM is defined to be a object of the winner’s choice, worth no more than 20 British
pence on January 21st, 2021. Examples include some crisps, a bazinga ball, a small
amount of olive oil, balsamic vinegar, or wine."

This market will resolve positive if Jonathan Oppenheim wins the bet (and corresponding 5000 ITEMS) and negative if he loses the bet (and pays the corresponding 1 ITEM).