The word "finite" refers to a quantity with known limits, regardless of its relative size to other quantities. A fixed number of greener pastures. A limited supply of water and fossil-fuel resources. The very nature of the Earth.
When something is finite, short-term perceptions during an individual's lifetime are not the real issue. People who say "they keep telling us oil will run out in twenty years, and it hasn't happened yet..." do not grasp the concept. The future is unpredictable but the assumption that more and more of a finite resource will be discovered is insane. There are also people who simply don't care about future shortages because they don't expect to be alive when demand finally exceeds supply. Or they assume that future generations will find magical ways to create raw materials from thin air, so they pass the buck to their descendants and live wastefully.
Man is genetically programmed to respond to short-term catastrophes and ignore long-term trends that have no apparent impact on day to day life. There is serious evidence that this outlook needs to change, and change can only begin when more people understand what "finite" really means.
Proof that the Earth is FINITE
An excellent debunking of Julian Simon's book "The Ultimate Resource"
Petroleum: A finite resource with no guaranteed substitutes
Those who think we can easily colonize space and ignore the limits of our own planet are dreaming. A quick look at the cost and complexity of sending seven Space Shuttle astronauts into Earth-orbit should demonstrate the folly of shipping billions of people to distant planets to alleviate population pressures on Earth. Travel to other planets is a fascinating goal which may or may not be achieved at some point, but it will almost certainly be done on a small scale (by people willing to take enormous risks) and it will never allow us to ignore problems at home.
Cornucopian "optimists" like the late Julian Simon claim that human ingenuity can overcome all resource limits by providing substitutes for anything that runs out. But there is scant evidence that this is occurring today, and it certainly doesn't pertain to large-scale resources like water and land, which are becoming increasingly scarce per capita. They talk about the shrinking size of computer chips or relative gains in agricultural production, and claim that limited progress in specific areas implies an infinite potential for improvement in all uses of resources. These "far-thinking" people can't explain how we're going to feed 9+ billion people by 2050, when close to a billion are already going hungry. They can't explain how a state like California with annual population growth exceeding 500,000 can continue to supply water to all its residents. All they talk about is our "inability to predict the future" and the magical THEY, who will save us (via increasingly elaborate technology) from any problem that arises.
The human mind is very resourceful but the laws of thermodynamics and entropy do not allow us to create an endless supply of physical matter from a finite supply of atoms. It's often pointed out that the Sun provides more energy than the Earth will ever need (at least until it burns out in the distant future) but the Sun's energy is restricted by the surface area of the Earth and the finite volume of matter it interacts with. Solar energy is also widely scattered and will never be completely available to us.
It's true that the universe is infinite for all practical purposes but this has nothing to do with the very real limits on our isolated planet. Are we to eat and drink solely from the "power of the human mind" in years to come? Please don't be fooled by people who tell you that one plus one equals infinity.