Last Thursday, Emanuel School’s Sixth Form Physics students were treated to a talk by physicist Dr Mountain. This visit covered numerous topics, walking listeners through a detailed history of the nature of black holes and equipping them with the general knowledge needed to understand some of their more intriguing properties.
However, to understand the nature of black holes, we must first understand what they really are. As a star evolves throughout its lifespan, it may, if it began with enough mass, explode into a supernova, which may then itself birth a black hole. Dr Mountain explained, with a few enthusiastic contributions made by the audience, that a black hole is a region of space with a phenomenal amount of mass densely packed together, giving it the strong gravitational pull most people know it for. This pull is strong enough to cause its environment to act rather unusually – as an example, not even light, the fastest particle/wave in the universe, may escape the pull of a black hole past a certain point. This point of no escape for any object is called the black hole’s “event horizon”. The stronger the pull of the black hole, the further the event horizon stretches from its centre.
Now, students were quick to ask about the consequences of these phenomena. If black holes can only get larger as they absorb more and more mass forever, what hope do we have of surviving them? Dr Mountain answered these enquiries in quick succession. Pupils that attended the talk were enlightened on why this is not the case, with the topics of women in science, time dilation and Hawking radiation all discussed. Near the speed of light (and when near a black hole), time becomes warped, to the point where it becomes an almost useless measurement. Students will be able to recall, interestingly, that orbiting a black hole is the same as moving forward in time, due to its strange properties. The theory of relativity, that time warps near lightspeed, was conceived by Albert Einstein and his first wife, Mileva Maric. Whilst very intelligent, Maric was not allowed to gain a diploma despite having previously attained results equal to Einstein in physics. 1900 was a difficult time to be a woman in science.
Luckily for us, there are ways for a black hole to lose energy (and therefore mass). Quantum field theory, Dr Mountain explained, allows for energy to be transferred on very small levels from a surrounding area to create a particle and an antiparticle. Normally these would break apart and release the energy back into the surrounding area, but if this process happens on the point of no return (the event horizon) some of these particles will not annihilate and will escape the pull of the black hole. This is called Hawking radiation. These were first seen in a photo generated by computer scientist Katie Bouman.
Despite what seems to be an incredibly detailed understanding of the universe, the physicist stated, there are plenty of phenomena we do not truly understand. However, as both our culture and our understanding of the world around us progresses, one thing is for certain – hard work and curiosity will never fail to aid us in our scientific journey.
Mr Martin (Teacher of Physics)