Source: Colossal Black Holes Locked in an Epic Cosmic Dance at Heart of Galaxy Locked in an epic cosmic waltz 9 billion light years away, two supermassive black holes appear to be orbiting around each other every two years. The two giant bodies each have masses that are hundreds of millions of times larger than that of our sun, and the objects are separated by a distance roughly 50 times that which separates our sun and Pluto. When the pair merge in roughly 10,000 years, the titanic collision is expected to shake space and time itself, sending gravitational waves across the universe. . . . A thing of horror, black holes far enough away. Bob Wilson
Their "volumes" maybe aren't that much more? I was reading about these, and there's mention that a golf ball sized bit of one "weighs" as much as our sun. Very interesting that something can "shake" space and time. I also read somewhere, they think there's a tangible minimum unit of time, and it's not that much smaller than the current "tick" of atomic clocks.
"Volume" and "x-sized bits" are rather meaningless for black holes. Neutron stars are the heaviest scale where those concepts have meaning. Black hole radius is proportional to mass, and is about 3 km for the Sun's mass. An Earth mass would be the size of a marble, 0.35 inch radius. A galactic core black hole of 100 million solar masses thus has a radius of 300 million km, twice the radius of Earth's orbit around the sun. Our galaxy has a central black hole of 4 million solar masses, but some others are in the billions of solar masses. The heaviest known are 50 and 66 billion solar masses. All black hole and neutron star mergers shake time and space. While the energy is prodigious, with recent star-sized events releasing and radiating several solar masses worth of energy in a few milliseconds, the actual 'shake' we experience is still minuscule, as in a small fraction of a proton diameter. The future event above would be undetectable with today's gravity wave detectors, because the signal would be very far out of the frequency range window they can measure. I believe LIGO hears in the range of 10s to 1000s Hz. The merger above will need a detector that can hear down in the 0.0001 Hz range, requiring a very large space-based detector. That would be the Planck time, under 10E-43 seconds. Our current clocks are not even remotely close to that. "The Planck time tP is the time required for light to travel a distance of 1 Planck length in a vacuum, which is a time interval of approximately 5.39×10−44 s. All scientific experiments and human experiences occur over time scales that are many orders of magnitude longer than the Planck time, making any events happening at the Planck scale undetectable with current scientific technology. As of October 2020, the smallest time interval uncertainty in direct measurements was on the order of 247 zeptoseconds (2.47×10−19 s)." https://en.wikipedia.org/wiki/Planck_units#Planck_time
