Science Magazine

is celebrating its 125th birthday with a special issue that takes stock of some of the fundamental and still unsolved mysteries of our time. The magazine's editors compiled 125 questions that point out the gaps in our scientific understanding of the universe we live in.

Inventor Thomas Edison founded Science Magazine in 1880. Today, as the weekly publication of the American Association for the Advancement of Science, it boasts the largest circulation of any scientific journal in the world.

News editor Colin Norman says instead of looking back at papers published over the last 125 years, the magazine decided to tap the expertise of more than 100 reviewing editors to help it compile a list of 125 questions that focus on the limits of our knowledge -- questions such as, 'What is the universe made of?'

"We now know that the fraction of the universe that you can actually see - the stars and galaxies, is just a very tiny fraction of what's there," Mr. Norman says. "There is a lot of dark matter that we know is there that is holding the galaxies together. Some of this is just regular matter, but a lot of it (is) particles that we don't know what they are yet."

Editor Colin Norman says other questions are much more specific, for example, 'Can we produce an HIV vaccine that is effective?' That, he says, is "a big problem that has tremendous social consequences."

Editors found that questions are not so simple and one leads to the next. Take, for example, the human genome, the hereditary DNA sequence first mapped 5 years ago. Scientists were puzzled when they discovered humans have just 25,000 genes, much less than the 100,000 they had expected.

Having answered the question 'How many genes do we have?' Mr. Norman says, "We now have to answer the question, 'How can we be so complicated with so few genes?' And it has to do with how the genes are expressed, the way the genome is controlled, and so there are a whole series of really interesting questions that are opened up by that discovery that we really have very few genes."

Another provoking question is 'How can a skin cell become a nerve cell?' "Scientists have always wondered how it is that an embryonic (stem) cell can become any kind of cell in the body and the signals that steer that development into particular kinds of tissues," Mr. Norman says. "That has always been a huge question in biology, but it has become much, much more pertinent now that we can take stem cells and culture (grow) them."

All of the 125 unanswered questions featured in the current issue of Science Magazine reflect a sense of wonder about the unknown, the magazine's editor says, listing just a few examples: "What genetic changes made us uniquely human? What is the basis of consciousness? How are memories stored and retrieved? How do we remember our addresses, but forget where we left our keys? How did cooperation evolve? All of those things are really intriguing questions that not just scientists, but everybody else wonders about. Are we alone in the universe? How did life on earth begin?"

Even though the magazine came up with a symbolic number of questions on the occasion of its 125th year, Colin Norman admits they are only a small fraction of the puzzles that scientists are actually struggling to solve. Mr. Norman invites listeners to take a look at the list online at and let him know if there's an unsolved scientific mystery the editors might have missed.