What kind of test might scientists devise to figure out whether something is alive?

You can't test until you define what ';alive'; means. The most challenging part of your question is finding this definition!





This is something that philosphers, biologists, computer scientists, and more recently astro-biologists and maybe lots of other fields have worked on periodically for hundreds of years. There is yet to be a definition that satisfies everyone, though definitions have been agreed to in the context of specific research programs (like NASA's astrobiology initiative).





Wiki shows one attempt at a definition, but I have yet to see any definition that either does not exclude something that is clearly alive, or includes something that clearly isn't (and sometimes both!)





Wiki's definition: http://en.wikipedia.org/wiki/Life#A_conv鈥?/a>





A couple of American Astronomical Society Abstracts about this question:


http://www.aas.org/publications/baas/v33鈥?/a>


http://www.aas.org/publications/baas/v34鈥?/a>





Discussion on the different ways to approach defining ';life.';


http://www.tufts.edu/as/wright_center/co鈥?/a>





So, while your question is a good one, it is hard to even begin to answer.





In practical terms, there are various experiments that have been designed to test for some of the properties assigned to life in some definitions. The mars Viking lander had a few, one of which gave a positive result, however it was also pretty easy to come up with clearly non-alive mechanisms to generate the same result.





Summary of the ambiguous Viking life detection experiments: http://www.msss.com/http/ps/life/life.ht鈥?/a>What kind of test might scientists devise to figure out whether something is alive?
If it reproduces by itself (using basic surrounding death elements), it's life.





Now the complex eplanation:


Life is the characteristic state of organisms. Properties common to terrestrial organisms (plants, animals, fungi, protists and bacteria) are that they are cellular, carbon-and-water-based with complex organization, having a metabolism, a capacity to grow, respond to stimuli, reproduce and鈥攖hrough natural selection鈥攁dapt.





An entity with the above properties is considered to be organic life. However, not every definition of life considers all of these properties to be essential. For example, the capacity for descent with modification is often taken as the only essential property of life. This definition notably includes viruses, which do not qualify under narrower definitions as they are acellular and do not metabolise. Broader definitions of life may also include theoretical non-carbon-based life and other alternative biology.What kind of test might scientists devise to figure out whether something is alive?
There has generally been a set of criteria for the definition of life such as respiration, ingestion, excretion, reproduction, repair. However a couple of years ago scientists found a grain of salt that was trapped in a rock that was estimated to have formed around 200,000 years ago. In the centre of the salt grain was a small droplet of water that was found to contain bacteria. The bacteria were extracted and placed in a fresh water solution and given nutrients. Incredibly the bacteria were alive and immediately began to reproduce. This has meant that in broader terms scientists are now having to re-define life and really have not come up with the final answer yet.