This 2005 image provided shows a blow-up of one small area of the Hubble Ultra Deep Field used to identify where the distant "Big Baby" galaxy, centre, is located. Astronomers using the penetrating power of two of NASA's Great Observatories, the Spitzer and Hubble Space Telescopes, identified one of the farthest and most massive galaxies that once inhabited the early universe. The galaxy was pinpointed among approximately 10,000 others in the Hubble Ultra Deep Field (UDF), presently the farthest optical and infrared portrait of the universe ever taken.
This week, Collected Wisdom, in its infinite wisdom, tries to explain the infinite.
THE QUESTION
In the media recently, there was news that the expansion of the universe is speeding up, writes Don Campbell of Burlington, Ont. "My question is, into what is the universe expanding?" This, he writes, "brings up the mind-boggling concept of infinity." He wonders whether anyone ever put forward a rational explanation of infinity.
THE ANSWER
We're going to deal with the second part of this question first. A quick explanation of infinity can be found in the dictionary, where it is defined as infinite space, time or quantity.
For a deeper look at this, however, we turn to Adrian Moore, a professor of philosophy at Oxford University and author of the book The Infinite.
Whether we can make sense of infinity is a question that has exercised philosophers, mathematicians, physicists and theologians since antiquity, he writes. "There are certainly grounds for skepticism about infinity," he says, in part because we never encounter it. However, he thinks it would be rash to reject the concept entirely.
"Aristotle confronted this dilemma some 2½ millennia ago. He drew a distinction between what he called 'the actual infinite' and 'the potential infinite.' " The actual infinite exists all at once, like infinite space. The potential infinite is spread over time, like the endless ticking of a clock.
"Aristotle argued that we cannot make sense of the former, but we can make sense of the latter. Ever since then, this has been the orthodox view."
Now, back to the first part of the question: What is the universe expanding into? Here's one view courtesy of a podcast by Pamela Gay, an assistant professor of physics at Southern Illinois University, Edwardsville. She says it's a non-question.
Let's take the analogy of an expanding balloon. Inside the balloon is the universe. What's outside?
"We say that all that there is of space, all that there is of time, everything that is everything is inside our universe," she says. "So, if you go outside the universe, there cease to be dimensions, there ceases to be any time."
She points out that this "nothing" cannot be labelled as a something – "it can't even really be labelled as a nothing because our concept of nothing is space that still has dimensions and still exists in time." That's why it's a non-question, she says, because you end up at a philosophical breaking point.
Here's a final word from Dave Rothstein, an astrophysics postdoctoral fellow in the department of astronomy at Cornell University. Writing on Cornell's Ask An Astronomer website, he says that if the universe is infinite, its size doesn't change (infinity plus one is still infinity) and therefore it isn't expanding into anything. If the universe is finite, then it may be expanding into something, but we have no idea what it is.
HELP WANTED
- At the end of some TV commercials (usually for new cars or trucks), there is a block of fine print at the bottom of the screen that is so small and is on the screen for so short a time that it is impossible to read, writes John Vickers of Calgary. If it cannot be read, why is it there?
- What makes that distinct smell after someone comes in from the cold? Laura Glowacki of Toronto wants to know.
- Eric Morris of Montreal asks: How did the tradition of pouring Gatorade on the winning football coach start?
Let's hear from you: If you have the answer to one of these questions (or want to pose your own question) send an e-mail to wisdom@globeandmail.com. Please include your name, location and a daytime phone number.