Breakfast, black holes and spaghettification

I don’t know what meal times are like in other homes, but in ours they tend to be chaotic and unpredictable. Take a simple breakfast last week as an example. Nothing too fancy… there was literally only cereal on offer. But cereal boxes can be great conversation openers, especially if they are from the BEAR company and are covered in all kinds of interesting facts.

“Are black holes real and what is spa-ghett-if-ication?” Asked the 11-year-old, cereal box in hand.

And so it began… Before we had even had our first cup of tea! We (the oh-so knowledgeable parents) gave the simplest, most basic of answers, in the hope that it would suffice. It didn’t!

I stressed the word “in theory” a lot, as I knew I was dealing with a tough audience that would easily find many “black holes” of their own in our explanations. The six-year-old threw out most of our facts for theories of his own, no surprise there! Even Stephen Hawking would find a tough critic in that little guy.

So, in theory… black holes and spaghettification are…

A black hole is what is left behind after a stellar object implodes. Using the example of a star… at the end of its life, with fuel and resources exhausted, a star will collapse in on itself, with one big explosion, called a Super Nova; after the event, all the mass and gravitational force of the object has been squeezed down (condensed) into a much smaller space. Imagine you are hit by a shrink ray and your body is reduced to the size of an ant, but you still have the same mass (the mass of an object is the amount of matter it is made up of, and is usually expressed in kilograms (kg))!  Black holes may also be formed when two stellar objects collide.

The gravitational pull of a black hole is so strong that nothing can escape it, not even light… hence the name!

Image credit: Ute Kraus, Physics education group Kraus, Universität Hildesheim, Space Time Travel, (background image of the milky way: Axel Mellinger); Image source: Wikimedia Commons.

The size and scale of black holes

Black holes comes in two main sizes… stellar black holes and super massive black holes. Stellar black holes are usually 10 to 20 times as massive as the Sun; Super massive black holes can be millions, and even billions of times as massive as the Sun.

It is speculated that an intermediate sized black hole exists also, although non have yet been accurately identified. These would be in the region of hundreds of thousands of solar masses.

Then there is the possibility of primordial black holes, formed from the collapse of dense regions in the early Universe.

How can we ‘see’ black holes?

Because of the lack of light, we cannot actually ‘see’ black holes but we can see their effect on nearby matter. The gravitational pull of a black hole can create high energy light emittance from nearby objects, sometimes breaking the object, such as a star, apart or heating it up as it pulls it in. This light can be detected using such equipment as telescopes and satellite imagining.

The trick is… not to get too close

Black holes do not simply ‘suck’ everything into a central abyss! Matter can pass by, or orbit, a black hole without being drawn in. It depends, in part, on how close the object gets. There is a threshold, a point of no return, referred to as the event horizon or Schwarzchild radius. Outside of this radius, matter will no be drawn into a black hole, but beyond it, the required escape velocity exceeds the speed of light… which basically means… the gravitational force is so strong that nothing, including light, can escape.

Recent studies have confirmed that Magnetic fields have a part to play in the formation of the event horizon, and the draw on objects beyond its radius.

Which brings us to… Spaghettification

So what happens beyond the event horizon? Well let’s imagine that you are floating around in space and you get too close to a black hole; You have just crossed the event horizon! Your body will experience some extreme forces of gravity, but the biggest problem is that you will not experience the same forces of gravity throughout your whole body; there will be a gradient of gravitational pull from your feet to your head, called Tidal forces. So your feet are literally being pulled into the black hole at a greater rate than your head is… causing your body to lengthen. Hence the name spaghettification! Ultimately your body would be pulled into a long, thin shape until it reached it’s elastic limit and would be pulled apart… in theory!

Stephen Hawking, the man behind the theory of black holes and event horizons has recently changed his theory. He believes that, taking quantum theory into account, escape from a black hole should be possible. He is still working on the proof so I guess I’ll leave that discussion for another breakfast.

In the mean time I think I prefer to keep my spaghettification in a bowl, topped with bolognese… and a little grated cheese!

What do you think, have you any theories of your own to add?

**********

A little note: This post is not sponsored by BEAR in any way; My children just happen to like their cereals and I just happen to like that they are made with no refined sugars!