Will the supermassive black hole at the centre of our galaxy consume us all?

The headline of an online article1 posed this question: “Will Our Black Hole Eat the Milky Way?” It is a good question to ask. Should we, here on Earth, be afraid of the supermassive black hole at the centre of the Galaxy? With it acting like some sort of a super cosmic vacuum cleaner will it eventually suck up our home planet and the rest of the galaxy? The short answer is no. But let’s review why that is so, and you’ll see it is not quite the same answer that a secular astronomer would give.

Our galaxy, called the Milky Way, has a supermassive black hole at its centre. The black hole has a mass of about 4 million times the mass of the sun.2,3 The Galaxy as a whole has a mass of about 20 billion suns (assuming no dark matter4,5), which is about 5,000 times the mass of the super-massive black hole. This makes the mass of the black hole 0.02% of the mass of the whole galaxy. It’s very small but also the stars around the black hole, at the centre of the galaxy, remain in very stable orbits. Few are consumed by the black hole, and those which are, represent a very small consumption of the mass of the whole galaxy as a function of time.

So don’t worry. You have absolutely nothing to worry about. The amount of time it hypothetically would take the black hole to consume the Galaxy is practically longer than the age of the Galaxy, assuming only natural processes of decay, and collision with any nearby galaxies.

Essentially that supermassive black hole, located near Sagittarius A* (see Fig. 1), presents no problem just sitting there at the centre of the Galaxy. The orbits of the stars around it are stable.

sgrastar

Figure 1: Sagittarius A*. Credit: Chandra

Back in the 1970s, the astronomers Bruce Balick and Robert Brown realized that there was an intense source of radio emissions coming from the very center of the Milky Way, in the constellation Sagittarius. They designated it Sgr A*. The asterisk stands for exciting.1

In 2002, astronomers observed that there were stars zipping past this object, like comets on elliptical paths going around the Sun. Using Newtonian physics the mass of the central object can be calculated from the speeds of the stars orbiting, though Einstein’s relativistic physics is more accurate. So even though the central object could not be seen directly its mass could be calculated. And because of the permissible size that such a central object could be its density can be estimated. The only possible object with such density and gravity to affect the orbital speeds of the observed stars means it must be a black hole. In this case, it worked out that the black hole must have a mass several millions times the mass of our own sun. See Fig. 2.

sgrastar-bh-simulation

Figure 2: An artist’s illustration of Sagittarius A*. Credit: NASA/CXC/M.Weiss

In addition to the discovery of a supermassive black hole at the centre of the Galaxy supermassive black holes were discovered at the centre of most galaxies.

If you read almost any article about these objects you will also be told that at least some of these galaxies, i.e. those with supermassive black holes in their cores, are what are known as quasars (or quasi-stellar radio sources). Quasars were first identified from strong radio frequency emissions and as a result were determined to be extremely bright sources. Many are observed with very high redshifts and as such are assumed to be very distant, even tens of billions of light-years away. Because they are so bright they can be observed at the edge of the visible universe. That is how the standard thinking goes, assuming their redshifts represent distance in the cosmos.6

quasar-sdss-j11061939

Figure 3:  Artist’s impression of  the huge outflow ejected from the quasar SDSS J1106+1939, at least five times more powerful than any that have been observed to date. But this type of energy output is not observed in our own Galaxy from Sagittarius A*. Credit: ESO/L. Calçada, Wikimedia commons.

The idea is that quasars have this supermassive rotating black hole at the centre of the galaxy and the black hole pumps out a prodigious amount of matter and radiation from its north and south poles. See Fig. 3. It is the light coming from one of the poles, like a light beam from a lighthouse, which is assumed to be the source of the quasar’s stupendous brightness.

But there is a problem with that assumption. That may be the case for some of these objects but is it the case for the supermassive black hole at the centre of the Galaxy? It does not produce a blindly bright lighthouse beam. It does not appear to give off more energy than all the rest of the stars in the Galaxy combined as is believed in the case of quasars. Could it be that we are in the wrong position to observe it? Not in the beam of the lighthouse? But other galaxies? Take for example the elliptical galaxy M87 in the Virgo cluster with an enormous jet of plasma 5,000 light-years long emitted from its core, assumed to be powered by a supermassive black hole. See Fig. 4.

m87-hubble

Figure 4: The jet of plasma is easily seen coming from the giant elliptical galaxy M87. It believed to have a supermassive black hole at its core with a mass 2 billion times the mass of our sun. That is a mass equal to 10% of the mass of the Milky Way. Credit: The Hubble Heritage Team (STScI/AURA) and NASA/ESA

It is even an elliptical galaxy, not a rotating spiral, and is not generally considered to be a quasar. Though some classify it as an AGN because of the energy output from the galactic core. Or, as has become standard astronomical belief, quasars are not stable galaxies but galaxies where their supermassive black hole is gobbling up lots of stellar material. As this material hits the black hole at the event horizon7 it is converted into an enormous amount of energy as radiation, which is what is observed pouring out of the polar regions. It is possible.

But it is also possible that quasars are special objects – possibly even white holes, i.e. black holes running in reverse. These are objects that show the hallmarks of Creation. I having written about this idea that stemmed from Halton Arp’s alternative hypothesis that galaxies are born from the hearts of quasars and AGNs.8

Regardless of truth of the source of energy that powers a quasar are we here on Earth in any danger? The black hole at the center of the Galaxy is 26,000 light-years away. I don’t believe it can or will turn into a quasar and start gobbling up stars. See Fig. 5. But if it did, the argument put by the astronomers is that you wouldn’t even notice.

The black hole at the center of the Milky Way is not pulling in stars and other stuff like a giant cosmic vacuum cleaner. In fact it serves as a giant gravitational anchor for a group of stars to orbit around, and it is alleged that this has been the case for billions of years.

stellar-bh

Figure 5: An artist’s illustration of a black hole, with an accretion disk, consuming a star. This is not a supermassive black hole but one of stellar mass size, which also have been shown to have good observational support.9 Credit: ESO/L. Calçada, Wikimedia commons.

The accretion disk at the centre of the Galaxy is very small. The diameter of the event horizon is only about 17 times bigger than the size of our sun, yet contains within it the mass of 4 million suns. Astronomically speaking that diameter is very small. So an orbiting star needs to get close to be torn apart, and it doesn’t happen very often. But for a black hole to actually consume a star, the star needs to directly hit the event horizon.

The problem happens when these stars interact with one another through their own gravity, and mess with each other’s orbits. A star that would have been orbiting happily for billions of years might get deflected into a collision course with the black hole. But this happens very rarely.

Over the short term, that supermassive black hole is totally harmless. Especially from out here in the galactic suburbs.1

Astronomers describe the future problem that our galaxy will be faced with, that is, when the Milky Way collides with our neighbour galaxy Andromeda. They call the amalgamated galaxies Milkdromeda. Since the Andromeda galaxy is approaching our galaxy at a rate of about 100 km/s they are expect the two galaxies to collide in about 4 billion years. See Figure 6.

As you might imagine this is really not something to lose too much sleep over. Besides the Lord will have returned long before then. Also I believe He will personally get involved with His creation and thus no such event will ever occur.10

milkdromeda

Figure 6: Hypothetical view of Milkdromeda from Earth “shortly” after the alleged merger, around 3.85-3.9 billion years from now. This is derived from a computer simulation. Credit: NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Astronomers also believe that the sun will die in about 5 billion years, and thus this future won’t be our problem because man will not be around to experience it. They have no eternal hope and as a result all they can hope for is that science will develop the technology to transplant human consciousness into a computer and/or robot body to give them some sort of eternal life.11 One astronomer laments:

Well, fine, with my eternal robot body, it might still be my problem.1

But on one thing I must agree with them;

For our purposes, the black hole at the heart of the Milky Way is completely and totally safe. In the lifetime of the Sun, it won’t interact with us in any way, or consume more than a handful of stars.1

So don’t worry about such stuff and get out and get busy sharing with the lost the one and only way to eternal life—Jesus Christ.

References

  1. Cain, F., Will Our Black Hole Eat the Milky Way? UniverseToday.com, August 15, 2016.
  2. Eisenhauer, F., Schödel, R., Genzel, R., Ott, T., Tecza, M., Abuter, R., Eckart, A., and Alexander, T., A geometric determination of the distance to the galactic center. Astrophysical Journal 597, L121–L124, 2003.
  3. 1 unit here is called a solar mass, and equal to about 2 × 1030 kg.
  4. Dark matter is assumed to exist in a spherical halo around the galaxy even though never observed. The assumption of its existence is based on the dynamics of stars and gasses, which we do observe. If the hypothetical stuff did exist the mass of the Galaxy could be about 5 times greater than this estimate.
  5. Hartnett, J.G., Why is dark matter everywhere in the cosmos?, March 31, 2015.
  6. Hartnett, J.G., The distances to quasars, March 30, 2016.
  7. The event horizon is where even light cannot escape the strong gravitational pull of the black hole. Above it sits a rotating accretion disk, from which some energy is derived as nuclear reactions are initiated.
  8. Hartnett, J.G., The heavens declare a different story! Journal of Creation, 17(2):94-97, 2003.
  9. Hartnett, J.G., What impact does the detection of gravitational waves have on biblical creation?, February 16, 2016.
  10. Hartnett, J.G., Our Eternal Universe, Journal of Creation, 30(3):104-109, 2016.
  11. There is now a big scientific push into this sort of thing, called transhumanism. Some recent movies have represented this idea, where man makes his own form of eternal life, by uploading his consciousness into a computer or better yet into matter itself. For example, the Johnny Depp movie Transcendence, where in the end the lead character uploaded his consciousness into a drop of water. Since the materialist believes that matter is all there is, this is his only hope. So sad. But it behoves us to reach the lost with the message that Christ gives, the only true message of eternal life.