» life on Earth
life on Earth
Can we use artificial photosynthesis to stop global warming?
Submitted by Saavik Ford on Mon, 7/13/2009, 3:03 PM
Plants are amazing little chemical ... well, plants. In the process of photosynthesis, they take carbon dioxide and water and turn it into sugar and breathable oxygen. We have been adding carbon dioxide to Earth's atmosphere at dangerously high rates, leading to global warming, but could we reverse the process by doing what plants do on some kind of industrial scale?
Maybe. There are some groups working on the problem, called artificial photosynthesis. The main difficulty is that it requires energy to turn a planet-warming molecule of carbon dioxide into a nicely breathable molecule of oxygen. Plants solve this problem nicely using solar energy and a very complex chain of reactions involving many steps and many catalysts. If we are to engage in artificial photosynthesis on an industrial scale, we will need to find cheap (preferably not very polluting) catalysts and probably a different chain of reactions.
But why not just do it the old-fashioned way? Plants require a lot of water and other resources to do their neat little chemical trick, so we might find a more efficient way to do it in the lab. Still, many climate change agreements and proposals do involve using "offsets" like planting trees to eat up some of the carbon dioxide produced by industry. Natural photosynthesis (aka plants!) also provide lots of side benefits not produced by artificial photosynthesis (like water filtration, storm surge absorption, food, shelter, beauty - the list goes on).
Tags:
Why must life metabolize?
Submitted by Saavik Ford on Thu, 6/18/2009, 12:30 PM
The universe is a place that, all other things being equal, tends towards equilibrium, or balance. In other words, molecules and atoms will not spontaneously organize themselves into towers against the pull of gravity – but trees (among other examples) will. Molecules and atoms will not spontaneously organize themselves into highly concentrated solutions of sugars and salts in small droplets of water – but single-celled organisms in a pond will.
Without life, the tendency in nature would be for the towers of trees to fall – as happens when they die. The tendency of solutions inside cells is to disperse – as happens when they die. It is the metabolic processes of the living thing that prevents trees from falling or cells from dissolving. Also, without their towers, or highly concentrated solutions, these organisms cannot reproduce, since reproduction requires particularly delicate chemical processes to all go right in order to work. The organism uses metabolism to create a protected environment for its reproductive chemistry to go forward.
Metabolism is what changes the environment of an organism to allow that organism to live and reproduce. No metabolism, no life!
Tags:
What is life?
Submitted by Saavik Ford on Thu, 6/18/2009, 12:23 PM
Maybe an odd question for an astrophysics FAQ, but of course it’s a question that we need to answer if we’re going to look for aliens!
It has been surprisingly difficult to get scientists to agree on a universal definition for life; however, in very general terms, most would accept that life must at least 1) reproduce (make copies of itself) and 2) engage in some form of metabolism (cause the conversion of chemicals from one form to another for use by the organism). Wikipedia has a very reasonable discussion on the arguments over the definition of life and offers a more rigorous definition.
Tags:
