Out of the many great secrets of the universe we have uncovered, the presence of Black Holes has got to be one of the most important. The space-time bending nature of the black hole which even Einstein couldn’t take in, has awed many a astronomer and philosophers alike. With a richer understanding (or is it incomplete?), misconceptions grow richer too. The same rings true of Black Holes as well. The purpose of this article is to see what common misconceptions exist about black holes, how these concepts were understood the wrong way, and what the true way of understanding is.
Misconception 1: Black Holes “Suck” Everything In
Since our childhood, we have been led to believe that, black holes are huge scary matter akin to an abyss that “sucks” everything that dares to go near it. But that is not quite the truth, Infact this misconception stems from a very simplified perception of gravity which calls for gravity as an invisible force that pulls everything towards the center of the object. In reality, things are much more complex than that- a Black Hole is a bend, perhaps a rupture or an aberration, in space-time itself.
Yes, in their proximity, black holes do have intense gravitational fields, but objects need to be close with specific trajectories to be “sucked” into the black hole. The matter that manages to be pulled into the black hole manages to be stuck in the accretion disk which is a ring-like band of matter in the black hole. These discs release energy while the object itself slowly falls towards the event horizon.
Misconception 2: Nothing Escapes a Black Hole
This common misconception is neither totally true nor entirely false. Nothing could escape the singularity of a black hole, not even light itself, or so it was believed. After all, all the scientific evidence pointed in that direction. But in 1972, Stephen Hawking introduced the concept of Hawking’s Radiation, which stems from the theoretical observation of subtle radiation coming from black holes.
Normally, for every particle that is to exist, it has its antimatter. These two “opposites” upon interaction with one another negate each other’s existence- much like the different signed integers in mathematics. But on the event horizon of the black hole, matter and its antiparticle might get separated. The positive energy radiates out of the black hole while the negative energy starts canceling out the energy of the black hole from within. This results in a theoretical “evaporation” (collapse) of the black hole. The radiation of positive energy from the black holes in such phenomena is commonly known as “Hawking’s Radiation”.
The first image of the Black Holes that lies at the center of the Milky Way galaxy.
Misconception 3: All Black Holes are Gigantic
The belief that all Black Holes are gigantic is, if not absolutely, partially wrong. Yes, there are supermassive black holes with diameters of over a million miles long, but the implication that all black holes are massive is incorrect. People think that black holes “eat” matter and therefore should be extraordinarily huge. Some reason that a Black Hole is formed when big stars collapse, and therefore the Black Holes themselves should be gigantic.
When we think of “massive” black holes it’s not that they are gigantic size-wise, but massive as in a body with a very large amount of physical mass. There are black holes called stellar black holes which typically range from about 5 to 10 times the mass of our sun. Stellar black holes form after stars exhaust their fuel required for fission, the remaining core then collapses under its own gravity forming a stellar black hole.
Misconception 4: Black Holes are Giant Cosmic Vacuums
Black holes aren’t giant cosmic vacuums that suck everything in their path, nor just holes in space-time itself. Black holes instead are collapsed stars in a very dense state coupled with an intense gravitational field. In order to fall into a Black Hole, you have to be sufficiently close to it. If you’ve not tipped across its event horizon, you can escape it, so the idea that it just sucks everything in like a vacuum cleaner would, is partially false. Therefore, in the initial days, Black Holes weren’t even dubbed “Black Holes”. They were instead known as “Gravitationally Collapsed Stars”.
Misconception 5: Black Holes Violate Conservation of Mass
Due to the misconception that Black Holes suck everything in their way, people are generally led to believe that what goes into the Black Hole disappears out of the universe. If it were so, that would contradict the law of conservation of mass. But the truth is, Black holes do follow the conservation of mass as the mass and energy that fall into the Black Hole themselves contribute to the mass of the black hole thereby increasing its gravitational field. Despite what happens to matter after it falls into a Black Hole is forever shielded from us once it crosses the event horizon, the total mass of the universe is conserved.
Misconception 6: Black Holes Lead to Another Universe
Black Holes lead to another universe. Or so it is often purported. But such claims might just be limited to sci-fi fantasies. The closest thing influencing such extraordinary claims that a Black Hole might tunnel us into another universe might be because of the theoretical possibility of the existence of a wormhole. Wormholes are often depicted as portals that help connect different points in space-time which allow for transportation faster than traveling at the speed of light. These portals were known as Einstein-Rosen bridges. For now, wormholes are limited to the pages of theoretical physics (and perhaps our imagination).
Misconception 7: Black Holes Are All the Same
Just like each person is different from another, one Black hole isn’t identical to another. The most common characterization of a Black Hole is that it is merely a thing that gobbles things up. If we are so unidimensional in our approach to what a Black Hole is, we might end up thinking that all of them are the same. But Black holes are of a large variance. They are often classified by their masses: stellar, intermediate, supermassive, and miniature. In addition, they also have 2 other intrinsic properties besides mass: “charge” and “spin”. So a Balck Hole would vary from another Balck Hole in either of these 3 quantifiables.
There is another class of Black Holes known as primordial black holes. Scientists also posit the presence of Black Holes from before the Big Bang. So if you took a look at the whole corpus of the types of Black Holes and the variation within these, you’d get an idea that all Black Holes are different.
This artist’s impression of how a Black Hole would look like. The labeling in the diagrams indicate the various terminologies used in Black Hole physics.
Misconception 8: Black Holes are Time Travel Portals
Films like Interstellar have captured the public imagination for their staggering portrayal of a Black Hole. Some have even been led to believe that black holes are time travel portals. To understand and then break through this myth, one must understand time dilation.
Time dilation is the idea that time passes differently to different observers at different speeds or different gravitational fields. It is based on Einstein’s Theory of Relativity. Theoretically, time dilation is possible near the singularities that Black Holes house, as time is bent and warped but time warps in a Black Hole also suggest that the future might affect the past.
Misconception 9: Earth is in Constant Danger from Black Holes
Too many sci-fi movies have led to the belief that black holes are scary and an active threat to humankind while in fact, they pose the most minimal (might be apt to say “non-existent”) threat to our existence. For Earth to be gobbled up by a Black Hole, first we must be near one. The closest black hole to the Earth is Gaia BH1 which is located 1,560 light years away from the Earth. At such a staggering distance, which would take a millennium and more to reach even if we traveled at the speed of light, the Earth is cozily tucked away from being ravished by a Black Hole. The observable universe is (possibly infinitely)vast and even though there are predicted to be more than 40 quintillion black holes in the universe, luckily none are considered a threat to our solar system
Misconception 10: Black Holes Are Rare in the Universe
Another common misconception about Black Holes is the myth that Black Holes are quite rare. It only seems so as the universe is vast and none of the black holes we have discovered to date lie even close enough for popular interest to surround it. Predictions of more than 40 quintillion black holes in our observable universe is a mindboggling statistic. Even in the Milky Way alone, there are around 10 million to a billion black holes. It’s not that black holes aren’t rare, it’s just that they don’t lie in close proximity to us.
Conclusion
Most of the misconceptions about Black Holes stem from oversimplification and misunderstanding of the concepts surrounding them. In short, black holes are common, harmless(for now), massive dense valleys in spacetime that vary in nature, and don’t let anything pass through them. For all we know, we don’t quite know the ultimate fate of the things munched up by a Black Hole. In a state of such observational and experimental evidence of the true nature of Black Holes, rejecting myths and embracing the fact that what is to be known about them dwarfs what we already know about them might be the way forward.
FAQ
What if the Sun was replaced by a black hole?
If the Sun were replaced by a black hole with the same mass as the sun, the celestial body’s orbits would remain unchanged. The temperature, however, would change as the black hole doesn’t provide heat or light anymore. On Earth, photosynthesis would stop and the earth would start to freeze. Down at the ocean, heat from the earth’s core could sustain proper temperatures so that marine life could still exist.
Can black holes harm us?
As of now, the closest black hole to us is 1560 light-years away from us. If the closest Black Holes to us is not close enough to damage us, think of how innocuous Black Holes billions of light years away from us are. But if there were to be a black hole near our solar system then it would have a drastic effect on all the heavenly bodies around us.
What would happen if we were to fall into a black hole?
If we were to fall into a black hole, any other observer from their point of view would see us fall slower and slower until our progress completely stopped and we froze in time. This happens because the light from the person approaching the event horizon is getting pulled by the enormous gravitational force of the black hole.
Falling into a black hole is a one-way trip as you would never be able to get out of it. It is because at a point, the gravitational force will pull things faster than light. From the moment you enter the event horizon, your feet would feel a greater gravitational force than your head so you would be “spaghettified”. You will never be seen from then.
Is time stopped in a black hole?
It would be better to say that we don’t quite know what happens to time and space in a Black Hole. This is because Black Holes are known to harbor “Singularities”- and these are where our current understanding of physics as we know it stops. For time itself comes to an end at these singularities, Black Holes are dubbed to be the “reverse of creation”.