145886
145892
Skywatching

Space: the final frontier?

Somebody described space as what stops everything from being in the same place.

For a long time that is exactly how we saw it — a void, nothingness, with lumps and clouds of stuff sparsely scattered around in it.

Some of the lumps are big enough to generate energy, and shine, while others do not, and we see them because they are being illuminated by that light.

Space was simply the gap between things.

For a while, 19th-Century physicists thought space had to be more than that. They knew that waves need to have something to carry them.

For example, sound waves travel through air, and if the air was removed, there could be no sound. Most of us have seen the high-school science demonstration where a bell or radio is put under a glass bell jar and the air sucked out.

The sound gets fainter as the air is removed, until finally we cannot hear it at all. On the same logic, light waves need something to carry them through space. They gave this substance the rather magical name of the luminiferous aether.

However, two things then happened. Experiments that should definitely have detected this aether failed to do so, and then James Clerk Maxwell showed that light, and any other electromagnetic wave, such as radio, X-rays and so on did not need a medium to carry them.

So the aether evaporated and space was back to being an empty void. Then came Einstein et al.

In the universe as Isaac Newton saw it, everyone experiences space and time in exactly the same way. Our positions and movements in space would be seen exactly the same way by everyone else and all our watches would tell us the same time, no matter what we were doing.

For most of our every-day activities, this idea works fine. However, in the bigger picture, this picture fails.

In this new picture, space is rather like a multi-dimensional rubber sheet, which is distorted by bodies such as planets, stars and other bodies, like cannon balls sitting on a trampoline.

The force we call gravity is the distortion of the fabric of space by these masses. The expansion of the universe is more like an expansion of that fabric, with all the galaxies, stars, planets and other things just getting carried along by the current.

Time gets distorted too. This distortion now impacts our every-day life.

For GPS satellites to provide the navigation services we now take for granted, this deviation, although tiny, has to be allowed for.

For objects such as the Earth, the bending of space and time is small. However, for large or dense objects, such as neutron stars and black holes, the space and time can be severely distorted or even fractured, as at the event horizon of a black hole.

That is not the end of the story.

There are two ways you can have no money.

One is simply to have nothing.

The other is to have borrowed, say, $100 and therefore owe $100.

You have $100 and your lender now has 100 anti-dollars. If they are brought together, they bring us back to zero.

However, you can spend the $100 or invest it, earning interest. You create employment and drive the economy. In the same way, the lender can combine your anti-dollars with others, to make strange investment vehicles that also earn interest.

Now, we believe space is like that. On the smallest scales, particle pairs, particles and their anti-particle partners, are coming into existence and usually promptly cancelling each other out, like borrowing and paying back immediately.

However, if the particles get separated, for example one of the pair gets trapped in a black hole, the remaining one wanders off into the universe to take part in whatever is going on.

To paraphrase a famous physicist: these ideas are weird. However are they weird enough to be true?

We still have a lot to learn about that “empty, cold, void.”

  • Mars lies in the west after dark. 
  • Jupiter, shining like a searchlight, rises around 2 a.m.
  • Saturn is up at 4 a.m.
  • The moon will reach first quarter on the 11th.


More Skywatching articles

About the Author

Ken Tapping is an astronomer born in the U.K. He has been with the National Research Council since 1975 and moved to the Okanagan in 1990.  

He plays guitar with a couple of local jazz bands and has written weekly astronomy articles since 1992. 

Tapping has a doctorate from the University of Utrecht in The Netherlands.

[email protected]



142356
The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

Previous Stories



145512


136613