When two black holes collide and merge

Amazing stuff!

"A decade ago, scientists first detected ripples in the fabric of space-time, called gravitational waves, from the collision of two black holes. Now, thanks to improved technology and a bit of luck, a newly detected black hole merger is providing the clearest evidence yet of how black holes work — and, in the process, offering long-sought confirmation of fundamental predictions by Albert Einstein and Stephen Hawking.

The new measurements were made by the Laser Interferometer Gravitational-Wave Observatory (LIGO) ... The results reveal insights into the properties of black holes and the fundamental nature of space-time, hinting at how quantum physics and Einstein’s general relativity fit together. ..."

From the abstract:

"The gravitational-wave signal GW250114 was observed by the two LIGO detectors with a network matched-filter signal-to-noise ratio of 80. The signal was emitted by the coalescence of two black holes with near-equal masses 𝑚1=33.6+1.2−0.8⁢𝑀⊙ and 𝑚2=32.2+0.8−1.3⁢𝑀⊙, and small spins 𝜒1,2≤0.26 (90% credibility) and negligible eccentricity 𝑒⁢≤0.03.

Postmerger data excluding the peak region are consistent with the dominant quadrupolar (ℓ=|𝑚|=2) mode of a Kerr black hole and its first overtone. We constrain the modes’ frequencies to ±30% of the Kerr spectrum, providing a test of the remnant’s Kerr nature.

We also examine Hawking’s area law, also known as the second law of black hole mechanics, which states that the total area of the black hole event horizons cannot decrease with time.

A range of analyses that exclude up to five of the strongest merger cycles confirm that the remnant area is larger than the sum of the initial areas to high credibility."

Ringing Black Hole Confirms Einstein and Hawking’s Predictions "New observations of a merger of two black holes confirm decades-old predictions by Albert Einstein, Stephen Hawking and Roy Kerr. The findings emerged from analyses led by Flatiron Institute astrophysicists using the clearest measurements to date of a black hole merger taken by the Laser Interferometer Gravitational-Wave Observatory (LIGO)."

GW250114: Testing Hawking’s Area Law and the Kerr Nature of Black Holes (open access)

Physicists bring human-scale object to near standstill, reaching a quantum state

Amazing stuff! Mind boggling!

"In the last few decades, physicists have found ways to super-cool objects so that their atoms are at a near standstill, or in their “motional ground state.” To date, physicists have wrestled small objects such as clouds of millions of atoms, or nanogram-scale objects, into such pure quantum states.

Now for the first time, scientists at MIT and elsewhere have cooled a large, human-scale object to close to its motional ground state. The object isn’t tangible in the sense of being situated at one location, but is the combined motion of four separate objects, each weighing about 40 kilograms. The “object” that the researchers cooled has an estimated mass of about 10 kilograms ...

The researchers took advantage of the ability of the Laser Interfrometer Gravitational-wave Observatory (LIGO) to measure the motion of the masses with extreme precision and super-cool the collective motion of the masses to 77 nanokelvins, just shy of the object’s predicted ground state of 10 nanokelvins. ..."

"... We prepared the center-of-mass motion of a 10-kilogram mechanical oscillator ... The reduction in temperature, from room temperature to 77 nanokelvin, is commensurate with an 11 orders-of-magnitude suppression of quantum back-action by feedback and a 13 orders-of-magnitude increase in the mass of an object prepared close to its motional ground state. Our approach will enable the possibility of probing gravity on massive quantum systems."

Physicists bring human-scale object to near standstill, reaching a quantum state | MIT News | Massachusetts Institute of Technology The results open possibilities for studying gravity’s effects on relatively large objects in quantum states.

Approaching the motional ground state of a 10-kg object (no public access)