Is it possible for something to escape out of a black hole?
Black hole- a mystery of our universe that is both equally fascinating and scary at the same time. Fascinating? Understandable. Scary? Why is it Scary?
Ever wondered what’s inside a black hole? What would happen if you fall in a black hole? Can anything come back outside of a black hole? While it might take a lot more research for space scientists to figure out conclusive answers for the first two questions, the answer to the third one is highly conclusive and thus, the short answer to it, is ‘No’.
The Long Answer:
Most of you curious minds have asked the right question. Why? Explain with reason, why isn’t it possible for something or anything to escape out of a black hole?
First, let’s understand what escape velocity is. Escape velocity (or escape speed) is the minimum velocity that is required to escape the gravitational influence of a primary body (planets, moons, stars etc). For instance, consider the escape velocity of Earth i.e 11.2 KM/S. An escape velocity of 11.2 km/s means that any object (rocket, spaceship, artificial satellite etc) having a velocity less than 11.2 km/s cannot escape earth’s gravitational influence, and would fall back to the surface because of the earth’s gravitational force. The outermost layer of the earth’s gravitational influence is Exosphere. Beyond the Exosphere, the earth’s gravitational influence drops drastically and an object will no longer experience gravitational acceleration towards the earth’s surface.
Similarly, a black hole has its own break point as well, beyond which its gravitational pull is extremely high, and outside which it drops drastically. This break point is called “Event Horizon”.
Escape Velocity is directly proportional to the mass of the primary body. For example, the escape velocity of Sun is 617.5 KM/S. We know that, the mass of Sun is much greater than that of the Earth. Hence we can see this huge difference in the escape velocity of these two.
Escape velocity can be expressed as :
As already mentioned, escape velocity of a primary body is directly proportional to the mass of the body. Thus, higher the mass, higher the escape velocity. For reference, the mass of Earth is 5.9722×10²⁴ kg, and that of the sun is 1.98847×10³⁰ kg. The mass of sun is 333000 times the mass of Earth.
One of the most recently discovered and also one of the closest black hole to Earth- Gaia BH3, is approximately 2000 light years away from Earth. (1 light year is defined as the distance travelled by light in 1 year).
The mass of Gaia BH3 is around 33 times the mass of our sun. Which is approximately equal to 66×10³⁰ kg. If we use the mass of Gaia BH3 to calculate its Escape Velocity, we will get as a result, a huge number which will also be much greater than the speed of light (c = 3×10⁸ m/s) i.e 3×10⁵ km/s.
This means that the gravitational influence beyond the event horizon is so high that even light can’t escape from a black hole.
As of today, there has not been any known physical entity, object, particle or a wave that has the ability to travel with a speed faster than light. Hence, we can scientifically conclude that it is impossible for something (or anything) to escape out of a black hole.
Summary:
a) Escape velocity of a primary body is the minimum velocity required to escape its gravitational influence.
b) Escape velocity is directly proportional to the mass of the primary body.
c) The mass of a black hole is so high that its escape velocity is much greater than the speed of light.
d) Nothing is faster than the speed of light, and even light cannot escape from a black hole (speed of light < escape velocity of black hole).
Thanks for reading :)