LIGO is back, and it鈥檚 better than ever. On Wednesday morning, Earth鈥檚 premier gravitational wave hunter turned on for its second science run 鈥� and after the first run鈥檚 grand success, hopes are high for what this next six-month round of observation may bring.
Gravitational waves are the ripples that surge across space time when massive objects move. Although Einstein predicted their existence more than a century ago, we hadn鈥檛 seen direct evidence of them until last year. The Laser Interferometer Gravitational Wave Observatory (LIGO) saw two strong gravitational wave events in its first four months, and possibly a third weaker signal, each from a pair of black holes crashing together and merging. If that trend continues in the new run, we should see at least six events in the first half of next year 鈥� but detector upgrades may allow us to spot even more.
鈥淚f we measured 3 in the first run, we should measure something like 10 in the next half a year,鈥� says at Johns Hopkins University in Baltimore.
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Since the end of LIGO鈥檚 first observing run in January, both of its detectors have seen significant improvements that have raised their sensitivities by up to 25 per cent for some events. A third detector in Italy, VIRGO, is expected to join the twin LIGO detectors in Louisiana and Washington state this spring. That will let us pinpoint the source of the gravitational waves and see if they emitted any light in conventional wavelengths as well.
With these higher sensitivities, researchers expect to observe more black hole mergers, which could lead to a universal map of black hole distributions. If we鈥檙e very lucky, we may also see some neutron star collisions, which can help illuminate how stars evolve and die. Eventually, we may even be able to use gravitational waves to examine the expansion of the universe.
