Space - Shortish Piece for my Brother & Nephew

[Qualia]

I was speaking to my brother the other night and he asked me if I could write something simple for him and his little child explaining some of the basic concepts about space, time and quantum mechanics. I'm no expert on this and he knows it. All I do is read, make notes, amalgamate them, make notes from those amalgamations and try to make it easy for me to understand.

If anyone is interested this is the first chapter I will send him and it's about Space. If you notice any errors or things I should take out or include please let me know.

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Space

Part I – Introduction

Laozi’s Space

A long time ago, a Chinese man called Laozi pointed out that people build houses with wood and brick but the use of their house depends on the parts where nothing exists. That is, the usefulness of the house is always about the room inside of them. If a house didn’t have this room, it wouldn’t be a house.

He said the same thing about cups and bowls. People mould them from clay and mud but it is the space inside of them which make them useful. If they didn’t have this space, they wouldn’t be cups or bowls.

It’s a nice way of thinking about things in the world.  

To get another feel for space, imagine you’re standing in Trafalgar Square and it was a single atom. The nucleus made up of protons and neutrons would be about half the size of a grain of rice. The few electrons buzzing around inside that atom would be about 2,000 times even smaller.

Imagine you are still back in Trafalgar Square but this time you are going to remove all the space found in all the atoms which actually make up the famous Square. You’d end up with a little lump of matter about the size of a grain of rice weighing millions and millions of tons. There are stars like this in the cosmos which are called Neutron Stars and these stars are about the size of a large city. 1 cubic cm of a Neutron Star weighs about 400 million tons.

So, as you can appreciate, most of what we call reality is in fact made up of empty space. For Laozi, who lived about 2,500 years ago, this space was something and it was a very real and very useful something. For physcists 2,500 years later, space is also a very real and very important thing but how do we make sense of this space that looks and seems like nothing?

Weird Questions

Here are some more weird questions people have asked about space over the last 2,500 years:

What is space?

Why is there space rather than no space?

Why is space so vast and so big?  

What is space made of?

Why do things in space seem to have dimension?

Space & Motion

As we have seen, space seems to be a very important thing. If you think about Space on the cosmic scale, it seems to be a very big thing in which all the other stuff fits into. If you took everything away, absolutely everything, you are still left with empty space, not empty nothing. So, it seems space is some-thing but what?

To get an idea of what is space, early scientists started thinking about how objects moved through it. For example, as a skater glides across the ice, she is moving relative to everything around her. When she skates, she can see that she is skating and she can feel it.

But what happens if you take everything away from her, absolutely everything? The skater is now skating in absolute empty space. She’s in complete darkness because we’ve taken everything away, all the stars and all the galaxies, everything, so the question is, is she still skating? If we took away all there is from our skater what is she skating relative to? With respect to what is she skating?

You can do a similar kind of thought experiment with your own house. You will say it isn’t in motion relative to, or respect to your street or relative to England or Europe but if I’m flying in a rocket outside the Solar System, I can say your house is spinning relative to its orbit around the Sun.

In fact, I can say your house is rotating about 40,200 km every day whilst hurtling through space at about 100,000km every hour. You may not feel or notice anything but that doesn’t mean you’re not moving at enormous speeds relative to the Sun. 

Since Galileo, we have always understood motion as being relative to something, but if we took away everything, how would we know we are still moving?

This was a bizarre question and needed a Newton to come up with something based not only on solid reasoning but also a good set of equations to demonstrate that he was right.

Newton’s Stage-Space

For Newton, space was a stage. Quiet literally. Think Shakespeare.

Space was a stage in which everything you and I know, plays out and happens. Newton made a number of laws, including the law of gravity and motion to show to everyone how physical objects move about within it.

All love, all death, all happiness and sorrow play out on the great stage called Space. Space was an arena in which the entire drama of the universe did its thing.

Space for Newton was absolute, eternal and unchanging. So Space was like a god. But it was a passive god. Any action of a physical object couldn’t affect the stage (space) and the stage (space) couldn’t affect any action.

Newton’s Space-Stage allowed us to understand motion, yielding powerful laws of physics which predicted motion and which are still used today. Newton’s Space was a very real and very physical thing acting as a benchmark, the underlying principle for all motion.

If we found our skater skating or our Earth orbiting in absolute empty space and we asked, what are they moving relative to? Newton and scientists for the next 250 years would say, they are moving relative to Newton’s Absolute Space.

Part II – Light

Light

Einstein wasn’t so much into Newton’s Space but his ideas really affected our understanding of space.

Instead, Einstein was fascinated by light. He started thinking about light from quite an early age. He wondered what it would be like to run at the speed of light and if you could, would you be able to reach out and scoop a spoonful of the light stuff?

He imagined what might happen to your image if you ran at a mirror at the speed of light so that the light wouldn’t have time to reflect your image and you’d simply disappear.

Einstein was thinking about these kinds of weird things when he was barely a teenager.

He knew that the speed of light was a measure of distance. If you say to me, Andromeda Galaxy is 2.5 million light years away; you are giving its distance to me in light years. He knew light travels at exactly 300,000 km every second and he knew that speed is simply how far something travels divided by how long it takes to get to a particle point. That is, space divided by time.

In a Newtonian universe, if you measured how much time it took for something to happen and how much space it travelled, and I did the same thing, assuming our instruments and measurements are spot on, our answers would always agree. There was an absolute absoluteness about Newton’s universe.

But Einstein thought there wasn’t something quite right with this idea.

Speed of Light

Imagine a rocket shots off at 100,000 km a second and on the countdown a light beam streaks off at the exact moment. You measuring those events will see the light shoot off at 300,000km a second and the rocket shoot off at 100,000km a second and conclude that the light is speeding away from the rocket at 200,000km a second.

Imagine now that the rocket is coming towards you. You measure this speed and record 100,000 km a second. At some moment the rocket fires on its lights and you measure this light. You’d think the speed of light travelling towards you would be the 300,000 km per second plus the extra 100,000 km per second increase due to the rocket speeding towards you and pushing the light out at that extra speed.

But in either case you’d be wrong. In the first example, Mr. Rocket Man would actually say to you, “Nope, I also measured the light speeding away from me at exactly 300,000km a second.” And in the second case, you would also say, “Nope, I never measured the rocket’s speed pushing out the light any faster towards me.”

This is just weird. Einstein realized that Newton’s physics was all wrong. Although it works and works extremely well and in fact we still use his equations to send satellites up into space, for example, it doesn’t describe reality. Einstein found that to have this absolute speed of light for anyone measuring it, space couldn’t be absolute as Newton had thought.

In fact, because speed was in each example being measured and speed is simply space divided by time, time itself could not be an absolute thing and if space and time are the measuring sticks we use for giving out speeds, then space and time must be deeply intertwined and connected. 

Not only was motion relative as Galileo had shown, but now, contrary to what Newton had shown, space and time were relative.

They always show Einstein as an interesting looking old man but in fact he did most of his great work as a young man. At the age of just 25, he transformed our understanding of reality. He realized with a set of remarkable equations and papers that time affects space and space affects time. And from the year 1905 onwards it was no longer sensible to talk about Space and Time as somehow being different entities or ideas but in fact just one entity called Spacetime.

Spacetime

Essentially, Einstein demonstrated that motion is a combination of space and time. And that the combined velocity of anything through space and time is always equal to the speed of light.

So, for Einstein, we not only have motion through space which we can call Space Motion but we also have motion through time which we can call Time Motion.

The faster you move through space, the slower time will pass, and the slower you move through space, the faster time will pass.

A parked car isn’t moving, so all its motion is going through time. If the car speeds off, some of the time motion will go into space motion, so time slows down.

So, thinking about space and time as equal motions, if you had no motion through space, you’d have absolute motion through time. And if you had absolute motion through space, you’d have no motion through time. In other words, if you never wanted to grow old, all you’d have to do is travel at the speed of light.

Experiments have been set up and it has been found that for every 3 hours we pass at rest on Earth, 2hrs pass for something travelling at half the speed of light.  

Another way to picture Einstein’s Spacetime motion is to imagine a glass which can only ever be filled with two liquids. One liquid is called Space Motion and the other liquid is called Time Motion. The more you fill the glass with one of the liquids, the less room you have for the other.

The more you fill your glass with the liquid called Space Motion or Motion Through Space, the less you have for the liquid called Time Motion or Motion Through Time, and the more you fill with Time Motion, the less you can give to Space Motion.

This is one of the reasons why nothing can go faster than the speed of light. It is simply because there is no time motion to draw upon. Travelling at such an enormous speed through space leaves no time for time.

It’s quite a beautiful thought to realize that the star light you see at night is ageless.

Part III - Gravity

Gravity

This picture of reality also solved some deep puzzles about gravity.

Newton demonstrated that gravity is a mysterious attracting force between objects with a mass.

Galileo had shown that all objects in the universe will travel in a straight line unless a force acts upon them. So if the Moon had absolutely no straight line motion, it would fall pretty fast towards Earth. And if it did have sufficient straight line motion it should be able to just float away from Earth. So why, in either case, did this not happen? That’s the kind of thing the young Newton was asking himself. It wasn’t really about apples after all but why didn’t the Moon fall towards Earth like apples do or just drift away from our night sky?

To see what Newton came up with draw a large dot on a piece of paper and then draw another smaller dot further out and label these features the Earth and the Moon. Now draw a little arrow from the Moon dot in the direction of Earth. That's how much the Moon is falling every minute. But in that same minute it must also have a constant straight line velocity as Galileo pointed out otherwise it would just fall towards Earth like the apple. So you draw another little arrow out from the Moon pointing sideways.

You can draw another Moon with its two little arrows on each of the other cardinal points, each time showing that the Moon is simultaneously falling and moving sideways. If you add these sideway vectors to the falling vectors and connect them, you will end up with a circle. So you draw this circle around the Earth dot and through each of your Moon dots and you label this, the Moon’s orbit.

Newton showed that the Moon is prevented from travelling out on its natural straight line velocity due to some invisible force he called Gravity, but it doesn’t come crashing to Earth due to its natural inclination to always push out in a straight line. The same goes for all the other planets or objects of sufficient mass or velocity orbiting the Sun. It’s a question about forces.

The circulating spacestation ISS, or any other little satellite up there in space, move around the Earth on these Newtonian principles. They are always in natural free fall along with everything else inside of them. That's why austronauts are weightless. It isn’t because there is no gravity up there in space, for they are only 420 km from the surface of the Earth, but because they are constantly falling towards Earth in free fall and yet their spacestation is pushing out on a straight line velocity, when these two forces equal out, we end up with an orbiting circle.

Newton’s laws give exact predictions about gravity and the way it works on mass and velocity but he gave no indication of why it works in this way.

Einstein’s Fabric

Einstein worked out a mechanism for gravity whose secret lay in the nature of spacetime itself. Imagine a rock musician’s drum and imagine its surface was space. If space was flat like this drum surface, objects placed on it would just roll around obeying Newton’s laws of gravity and motion. But if we replaced that drum surface with a latex surface which obviously stretches and bends what would happen?  

If something heavy were placed on top, the latex would cave in a little and anything that orbited this larger object would travel around the indentation made by the larger object. Einstein worked out that this is why Newton’s gravity works as it does. Gravity is essentially the warping of spacetime by the objects within it. Gravity is quite literally the shape of spacetime.

Even though Newton’s laws are very useful and work, again they don’t really explain reality. We now understand that the Moon is kept in orbit not because it is being pulled to Earth by some mysterious force but rather because it is rolling around a curve in spacetime’s fabric that the Earth has created.  

Part IV – Quantum World

The Subatomic World

Up until now we’ve been dealing with matters of space and things which you can see but at the microscopic level it was also found that even if you removed everything, you’d still find space is anything but nothing.

Right down at the subatomic level, smaller than atoms themselves, it has been discovered that particles pop in and out of existence. They erupt from nowhere, annihilate each other and just as quickly disappear.  The main problem is that we cannot really see these subatomic particles, but we can see what they do.

If you took two very light and very small metal plates and placed them almost together, some subatomic particles are excluded because they can’t fit between the plates. These excluded particles that we just cannot see push against the plates, moving them closer together, as if it were empty space itself pushing on them.  

Higgs Field

The CERN particle accelerator accelerates particles at 99.9% of the speed of light, smashing them into each and from the shower of debris scientists can discover hundreds of other subatomic particles.

Now you may have heard about the Higgs Boson particle and how the media termed it the God particle. This subatomic particle is thought of as being essential to giving matter mass. All particles contain mass and without mass, atoms couldn’t combine. But the question is, where does mass come from? What creates it and why do different particles have different masses?

Higgs asked himself what quantum space must look like and to get an idea imagine a sticky ocean. As subatomic particles move through it, bits of the ocean stick to them. Some particles will pass through the sticky ocean without much interaction, so these gain little mass, other particles will push harder to get through the ocean and so these will collect more mass. In other words, the more a particle interacts with the ocean the more mass they gain.

This sticky ocean is called the Higgs Field and is crucial in our understanding of space. It is everywhere; it gives everything its mass. Quantum space gives things mass.

That’s really quite a beautiful thing to think about.

Part V – Dark Energy

If you throw an apple in the air it will eventually slow, stop and then fall back due to the pull of gravity. Likewise, since the advent of the Big Bang, it was thought that the initial expansion of the universe must eventually slow down due to the collective pull of gravity from all objects and collapse in on itself.

But from studying exploding stars called Supernova and their rate of expansion after exploding, it was found that the universe was still expanding and speeding up in its expansion. It’s as if space has a springiness to it that doesn’t want to be compressed.

It was figured that there must be something that fills space and counters the pull of gravity, stretching the fabric of the cosmos. This something has been termed Dark Energy. Dark Energy seems to dominate the content of the universe and yet no one knows what it is.

Einstein’s Cosmological Constant

According to Einstein’s calculations the universe should be either expanding or contracting but this didn’t fit in with the idea that the universe was at rest, eternal and unchanging. So Einstein came up with the constant, a form of antigravity that would counter the inward pull of gravity and allow the universe to stand still.

About ten years later in 1929, Hubble discovered that the universe was not static but was expanding with the explosive force of the Big Bang. The need for Einstein’s cosmological constant was abandoned and Einstein himself considered his antigravity constant one of his greatest mistakes.

With the recent discoveries that the universe is accelerating, scientists are convinced that there is something in space pushing things apart. Just under a hundred years later, Einstein’s “biggest blunder” may be one of his greatest insights.

The End

At the moment it seems matter is held together by forces such as gravity which overwhelm the forces of Dark Energy, but this may not always be so.

Dark Energy could continue to push everything further apart. All the galaxies would drift further and further away from each other until we are left alone. Dark Energy could ultimately counter the attracting forces which holds things together, everything would disintegrate and be torn apart and the universe would become a very dark, very cold and very lonely place.

I'm not sure if this is a rather beautiful thing to think about or a rather sad thing, so being undecided we'll just call it a day here.

[jetstream]

Excellent write up Rob! very informative,I'm reading it again...!

[Qualia]

Thanks for the kind words, Gerry. If you think I should change or ammend anything before sending it to my newphew, please let me know. Would hate to think the little one is being misled.

[Bungielad]

What a great read and very well explained,

I must ask though.....what age is your nephew? And also does your brother have any knowledge of what your telling him already or is this the 1st he's going to hear about this kind of thing?

I only ask because when I tell my family about all this stuff it can kind of freak a few of them out due to it all being a bit mind blowing and to some of them frightening.

Although to folk like us this kind of understanding is fascinating, to some it can be a bit much to take inn all at once.

I have to say though I thoroughly enjoyed the read and hope your family do also.

Bungielad.

[jetstream]

Thanks for the kind words, Gerry. If you think I should change or ammend anything before sending it to my newphew, please let me know. Would hate to think the little one is being misled.

Rob,this will be excellent for him.Kids today are fortunate to have the opportunity to learn so much,so soon.This is great exposure for a youngster (and anyone) and will help 'plant the seed' for him to pursue an education.

[ollypenrice]

Great stuff.

I am disgusted beyond words by the scientific non-education I received at a school which liked to tell us it was in the national top ten.  (My foot.)  It was full of rubbish like, 'You don't need to know about relativity at this stage,' or  'You can think of valencies as little hooks,' as if the point of the course was to enable you to perform successful little calculations within in an utterly incomprehensible and decontextualized whole. In this dismal world light behaved like a billiard ball, angle of incidence piously equalling angle of reflection. I find piety incredibly boring and so that's how I found school science. If you'd told me that the angle of incidence equalled the angle of reflection until you took away the 'unused' part of the mirror I might have perked up! Oh yesss....

Where science should begin is with the BIG ideas like relativity, quantum theory and evolution by natural selection. Even the Big Bang is just a detail. In my school day these came last. The idocy of this approach leaves me fuming. The only thing I have retained from my schooling is the ability to speak French and the desire to assault conformity on sight. 

Olly

[Knight of Clear Skies]

Nice article, I love the idea of Laozi's space.

A few quick thoughts:

- Found a typo: "For Newton, space was a stage. Quiet literally. Think Shakespeare."

- Myself, I find the cannonball explanation of orbits the easiest to understand.

- Perhaps a few real-world examples would help. With Newtonian physics you can aim cannons, fly rockets and compute the orbits of planets. With relativity you can account for Mercury's orbit and build a working GPS system. Quantum physics is required to build transistors and computers.

[Qualia]

Thank you for your kind replies. Please don't thiink me rude for not replying sooner but the internet router at home died and I had to wait a couple of days for a replacement. Mr. Knight, thank you for your thorough read and I will certainly make sure I use some real-world examples and correct that silly spelling error.

I'm working on the chapter on Time and then I'll do one short one on QM which I really don't understand that well. I will make the three short chapters into a little booklet, the text as given with some pictures and each chapter will be accompanied with a CD of music which will hopefully evoke something of the concept.

The general idea is to give my brother something to read. He then digests it and reads one of the short sections to his son each night. My brother's not that versed on these issues so it will be good for him as well. I completely agree with Olly that in education, whenever it is possible, we ought to start with the Big Ideas. They're the most fun to play around with and the ones in which our imagination can really start to contemplate wonders.

I did something similar a while back on some Big philosophical issues and it seemed to go down well, so this time round it'll be something a little more on these astro related marvels.

Once again, thank you Jetstream, Bungielad, Olly and Knight for your kind considerations and input