Science Seen Time One author Colin Gillespie helps you understand the physics of your world.

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Expanding Space, Expanding Minds

Understanding physics can be satisfying. Understanding physics some physicists don’t understand brings super-satisfaction.

Many think they can’t understand physics. Seems to me that often it is physicists they can’t understand. I think anybody who can figure how to travel to another country can, with no more effort, understand a lot of physics. With two provisos: It should be explained in plain language; and it should have an explanation (lots of physics doesn’t).

BI’ve mentioned how the 2011 Nobel Prize for physics was awarded for discovering that space has been expanding at an accelerating rate for billions of years. The acceleration gives seeming substance to Dark Energy, yet it is a label with no explanation.

How can space expand? The concept is not easy to understand and is controversial. Many physicists say that it doesn’t. For example, Marcus Chown, a British physicist, science writer and cosmology consultant to New Scientist, once asked:

How is it possible for space, which is utterly empty, to expand? How can nothing expand?

Several physicists replied, assuring him that space is not expanding. They should know better. As far back as 1929 American astronomer Edwin Hubble’s now-famous measurements of galactic velocities confirmed Belgian physicist Georges Lemaître’s prediction: Space is expanding. It was of course understood the universe’s gravity must slow down the expansion; someday it may stop and then contract. This was what many thought; that Nobel Prize was for showing they were wrong.

Back to Chown. His premise―that space is nothing―is the problem. Albert Einstein changed his mind about space several times but in the end he said that it is something. The success of general relativity supports this. Indeed recent measurements show space is 70% of the mass-energy of the whole universe. But what exactly is space? If it is most of everything, then surely what it is is worth some careful thought.

Recently, serious scientists (the likes of Abhay Ashtekar, Richard Feynman, Carlo Rovelli and Lee Smolin) have been saying space is not continuous. Albert Einstein said the same thing in a letter to a friend before he died. Many signs say all these scientists are right: Space is granular. It is made of tiny pieces, pieces as in distinct things of a certain size (called the Planck volume), pieces which cannot be divided, pieces which (at least in principle) are counted and not measured.

So, space is made of many somethings. For convenience, let’s call these somethings flecks. Space expanding is this easy: Over time there are more flecks. For this there’s an easy explanation. Just like rabbits with a good supply of carrots, flecks can breed more flecks.

Coming: Stories physics tells about new space

Sources:

Marcus Chown (1993), New Scientist, 17 April, p. 32

Other material:

George Johnson (1999), “How Is the Universe Built? Grain by Grain”, The New York Times, December 7; http://faculty.washington.edu/smcohen/320/GrainySpace.html

“Metric expansion of space”, Wikipedia, accessed 4 May 2014, http://en.wikipedia.org/wiki/Metric_expansion_of_space

Image credit: Educational Observatory Institute, http://edu-observatory.org/olli/VD-C2BB/Week5.html

 

3 Comments

  1. Italo DeBlasi September 19, 2014 at 7:02 pm #

    I came to realize, some time ago, that space cannot be nothing. Nothing would mean that the interface between nothing and something would be the most corrosive interface in existence and would consume all that exists. The question is as has been asked, what is it? This notion that space is granular fits in with all we see around us, but again, what lies between the granules? Again it has to be something or there would be incessant consumption, because “nothing” abhors”something”. Perhaps, because there is a universe, no matter how many versions or subdivisions exist, the answer is that the granularity exists ad infinitum, ie. the further we dig, the more we will find. No matter how many boundaries we discover, there will always be something else on the other side of that boundary.

  2. Michael Sinatra September 18, 2014 at 10:04 am #

    The universe has always been accelerating Einstein’s theory of gravity one that contained what was called a “cosmological constant’. Dark energy the expansion of the universe is the opposite than that of ‘normal’ matter. Black holes ‘Big Bang particle accelerators’ scavenging matter in one universe to create life in another alternate multi universe. God The Universe is endlessly expanding to the point of infinity, a kinda ‘over-unity” energy — that is, it produces more energy than it consumes. Seems that time may just be a ‘frigment’ of our imagination :-)

  3. Arshad Usmani September 17, 2014 at 6:36 am #

    Don”t read this article. It will distrct your knowledge and will try to deviate and misguide. You shud read Stephen Hawking’s A Brief History of Time to understand the space and its expansion and then refer to your tex books.

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