THE USM SOUTHWORTH PLANETARIUM
70 Falmouth Street Portland, Maine 04103
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Founded January 1970
Julian date: 2458589.35
"Fourthly, black holes just look cool in photographs."
THE DAILY ASTRONOMER
Tuesday, April 16, 2019
Black Holes II
Well, yes, black holes are a "big deal," if you're a cosmically minded human. Thirdly, our solar system is moving around a supermassive one lurking in the galactic nucleus. Secondly, they might be portals to other Universes. First, the distortions they create in the space-time continuum are nothing short of high powered science fiction. Even the mention of black holes can do dodgy things to the causality stream. Moreover, they might be portals to other Universes and, possibly, our universe might have been spawned by a black hole in another Universe. What with all those considerations, how could black holes not exercise a deep fascination on any but the most hopeless astrophobe? (a term applied to those well adjusted souls who are afflicted with a morbid fear of outer space.)
Today, we continue answering black hole questions subscribers sent us last week!
How do astronomers know the masses of black holes?
-C.D.
Weighing black holes is not a simple matter, but, of course, you knew that, anyway. Astronomers can estimate the masses of black holes by measuring the speeds of the objects that revolve around them. For instance, in our own solar system, we can know the Sun's mass by measuring the distance separating the Sun and Earth and also our planet's orbital period. If we somehow managed to increase the Sun's mass, the planets in orbit around it would move faster. This relation between a revolving body's orbital speed and the masses of both it and its parent body is well established. The speeds of the stars around the galactic nucleus indicates the mass of the supermassive black hole around which they are traveling.
Do black holes really lead to other Universes?
-S.H. (No, actually, not THAT S.H.)
Not sure. In 1935, Albert Einstein and Israeli physicist Nathaniel Rosen developed a model of the "Einstein-Rosen Bridge," a hypothetical conduit through which a person could travel between two distant points quite rapidly. The more familiar term for this conduit is a "worm hole," as they are assumed to be quite small and, like a worm-forged tunnel through soil, inherently unstable. While this "bridge" is permissible physically, it is not known if it would connect remote points in the same Universe or a point in this Universe and one in another Universe. Another problem, apart from the problematic notion of its actual existence, is that it could collapse as soon as any material object infiltrates it. And, the tidal forces around stellar black holes are so powerful that any astronaut aspiring to visit another Universe would be literally reduced to his or her component subatomic particles before even approaching the portal, if it even exists in the first place. Don't despair! We have 566 days of Presidential campaigning left to enjoy. You don't want to leave the Universe yet!
When looking at the photo, is the black hole inside the ring, thereby making the distance from one side to the other the distance from the sun to Neptune? W.L
That region within the ring is the region defined as the "event horizon," the part of space beyond which nothing can escape, not even light. Yes, the supermassive black hole within the nucleus of M87 would fit inside Neptune's orbit. That is a vast amount of space (more than 2 billion mile radius.) Yet, remember that we're stuffing 6.5 billion solar masses inside that volume. Supermassive black holes are much larger than the stellar black holes that are laying waste to the star streams like picnicking children in your kitchen.
What is the Hawking "black hole message?"
Soon after famous cosmologist Stephen Hawking's remains were interred in Westminster Abbey, the European Space Agency used its radio antenna at the Cerebos station to beam a radio message containing his voice and the music of Vangelis was beamed to V616 Monocerotis, the region containing the closest known black hole to the solar system. As we expect nobody (sane) to be living in a black hole, this message will not receive a response. Instead, when the message arrives in AD 5475,* it will be swallowed. Some of Stephen Hawking's information is destined to be consumed by a black hole. Tell me that isn't the most morbidly cheerful idea anybody has ever had.