The Universe: Imagine the un-imaginable!

Author: Michel van der Meij (c) 2009

How to imagine the size of our vast universe?

The whole universe is almost empty!


How can we imagine the size of the universe?

The observable universe is said to be approx. 13.7 billion light years seen from earth in any direction. This means the observable universe is the shape of a ball. It doesn't say anything about the real size of the universe, neither about the real shape of the universe. We can only make conclusions by what is for us observable. Obviously, the universe itself will most likely be much bigger than what we can see, this because light of those more distant galaxies has simply said not reached planet earth yet.

So, let's go back to the original question, how to imagine the size of the observable universe. Since what we can observe is 13.7 billion light years away, the total observable area has a 2 times 13.7 billion light years diameter. Let's take this as our first reference X. The observable universe is 27.4 billion light years in diameter.
X = 27.4e9 light years

The diameter of planet earth is approx 12000km. It would take a ray of light 0.04sec (12e3 / 3e5) to travel that distance

How many seconds are there in a year? Well, that's simple, 365*24*3600 = 31536000
This means that planet earth is 0.04 / 3153600 = 1.27 billionth of a light year in diameter.
Let's take this as our second reference Y.
Y = 1.27e-9 light years.

This means that the ratio Z between the diameter of the observable universe and the diameter of planet earth equals:
Z = X / Y = 27.4e9 / 1.27e-9 = 2.16e19
That is a nice number, but if you can't imagine the size of the universe, then what does this number tell you? Nothing, right?

OK, let's do some down scaling, we scale down the size of the observable universe to the size of planet earth and then calculate the new size of planet earth in this much smaller universe. So for now, planet earth is the universe.
We know planet earth's diameter is 12000km (12e6 meter), so the original planet earth in small scale would then be:
12e6 / Z = 5.56e-13 meter in diameter.

Now, if we know that an atom is approx. 1e-10 meter in diameter, this means our planet earth has shrunk to
(1e-10 / 5.56e-13 = 179.8) approx a 180th of the size of an atom!!!

So if the entire observable universe is the size of planet earth (12000km diameter), planet earth would take a 180th part of an atom within this universe!!

Conclusion: Planet earth is absolutely nothing compared to the vast universe!

The whole universe is basically 'nothing'!!

Sure you know that our universe is a vast place of emptiness containing just a couple of hydrogen atoms per cubic meter. But what about the atoms themselves? How empty is an atom? How empty is a solid bar of gold for example?

A simple atom (hydrogen) has 1 proton in it's nucleus and 1 electron circling around it.
The physical size of a proton is approx 1.6e-15 meter, the electron being a factor 2000 smaller, so let's ignore that one.
We've seen from above that the size of an atom (any atom, really) is 1e-10 meter. This means that the nucleus of an atom is in fact only a 62500th of the total size of the atom with NOTHING in between the proton and the electron.

Let's upscale this one for a change, let's take an atom the size of planet earth 12000km in diameter. The nucleus would therefore be just (12000000/62500) 192 meters in diameter!!!
So in fact, there is a whole lot of nothing in a hydrogen atom as there is a whole lot of nothing in gold as there is a whole lot of nothing in the universe!!

Please note that the electron being 2000 times smaller, it would only be (192/2000) 9.6cm and traveling across the surface of the earth nearly at the speed of light around a 192 meter in diameter proton core!!! So you can imagine how strong the nuclear forces are compared to gravity...

OK, ok, I hear you say 'gold' is not 'hydrogen'. That's correct, in fact, the nucleus of gold consists of 79 protons and 118 neutrons. That means the nucleus of gold is of course bigger than the nucleus of a hydrogen atom. Still, the size is less than 3e-14 meter and probably closer to 1e-14 meter while the size of the gold atom is still about 1e-10 meter (3000-10000 times bigger). That means plenty of empty space left, even in a solid bar of gold!

Oh yes, just for reference. We said the diameter of an atom is about 1e-10 meter, if this is hard to imagine, just think that a straight string of 10 million atoms, laid out side by side, will in fact be no more than 1mm in length.

Is that amazing???

Some human fundamentals that I have observed

Think about this for a minute: What makes us really human is that we have asked ourselves for every observation throughout the millennia "why is that so?". Along with this curiosity, we have been given the ability to use creativity to drive an understanding towards an invention.