Resolution criteria

This market will resolve to YES if, by December 31, 2030, a peer-reviewed paper or official collaboration publication utilizing Type Ia Supernova (SN Ia) data from the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) finds statistically significant evidence of a local cosmic void (underdensity) with a density contrast of $|\delta| > 20%$ at redshift $z < 0.1$. "Statistically significant evidence" is defined as a detection at a $\ge 3\sigma$ confidence level, or an explicit claim of detection/evidence of such a void by the authors.

This market will resolve to NO if no such paper is published by December 31, 2030, or if the analyzed LSST SN Ia data rules out a local void of this scale at $z < 0.1$ (e.g., placing constraints that bound $|\delta| \le 20%$).

Notes:

• "Data from LSST" includes both official LSST collaboration publications and independent peer-reviewed papers using publicly released LSST SN Ia datasets.

• In the event of conflicting scientific papers, the market will resolve based on the consensus of the scientific community or official statements from the Rubin Observatory / LSST Dark Energy Science Collaboration (DESC).

Background

The "Hubble tension"—the discrepancy between the expansion rate of the universe ($H_0$) measured from the cosmic microwave background (67 km/s/Mpc) and local distance ladder measurements (73 km/s/Mpc)—remains a major puzzle in modern cosmology. One proposed late-time solution is that the Milky Way resides inside a large local underdensity, such as the KBC (Keenan-Barger-Cowie) void, spanning out to $z \approx 0.07$ to $0.1$. Proponents argue a ~20% underdensity could produce gravitationally driven outflows that inflate local measurements of $H_0$.

However, previous analyses of local Type Ia supernovae (such as the Pantheon sample) have contested this hypothesis, finding that the SN luminosity distance-redshift relation is inconsistent with a local void of $|\delta| > 20%$ at $z < 0.15$ at the 4-5$\sigma$ level (e.g., Kenworthy et al., 2019). The unprecedented volume and precision of Type Ia supernovae detected at low redshifts by the Rubin Observatory's LSST is expected to definitively map the local expansion rate and resolve whether a physical local void of this magnitude exists.

This description was generated by AI.