By Dr. Robert Thorson

Columnists are teased for being know-it-alls. I have three responses. First, I don’t know everything. Second, you don’t either. Third, I’m thankful there are things neither of us know. Otherwise, scientists would cease to exist.

In honor of my existence, I’ll share a holiday meal with you. I’m not talking about the calorie-laden meal at grandma’s house consisting of roast turkey, mashed potatoes, cranberries, pumpkin pie and drinks. I’m talking about a mental meal with anti-calories in the form of intellectual gristle. My meal will give you no nutrition whatsoever, no matter how long your brain chews away.

The raw ingredients for this lavishly catered meal were delivered by the editors of Science in its July 1 issue. From their catalog of 125 ideas that we don’t have answers for yet, but might have soon, I selected five to share with you. And now the table is set to begin.

In lieu of roast turkey: For a century, cosmologists have wondered why the “universe is expanding faster and faster, instead of slowing down as the laws of physics would imply. Is there some sort of antigravity force blowing the universe up?” The answer seems to be yes. Normal, everyday gardenvariety matter (the stuff that makes up the stuffing) and other exotic particles make up only about 30 percent of the known universe. The rest of what’s out there baffles the smartest of the smart physicists. But they have agreed to call it dark energy.

In lieu of the mashed potatoes: I think, therefore I am … fairly confused about everything. This is my spoof of Rene Descartes’ famous statement “I think, therefore I am.” Consciousness is no longer the province of philosophers. Cognitive scientists of many stripes — psychology, physiology, evolutionary theory, and computer science — have moved in to agree that mind is a manifestation of biochemical processes operating in our brains, which involve matter. The problem is that they have yet to “directly address the most enigmatic aspect of the conscious human mind: the sense of self.” The questions “Who Am I?” and “Why Am I?” do not have answers in science. At least not yet.

In lieu of cranberries: In 1997, Jeanne Calment died in southern France at the age of 122 years. Hers was the longest human lifespan that was well-documented. Scientists are busy experimenting with what they call “lifespan extension” in many animal models, with some success. Three factors are being investigated: a reduction in calories (not a good idea to read this on Thanksgiving; oh well); antioxidant chemistry; and reducing the amount of a growth-factor protein. The most important unsolved questions in this case are largely ethical, because the question “Who gets to live longer?” is not that different from the one “Who has to die younger?” Today, I’m just thankful to be alive.

In lieu of pumpkin pie: In 1864, Jules Verne published one of my favorite childhood books, “A Journey to the Center of the Earth.” Ever since, I’ve wanted to know what lies beneath. The answer, even 40 years after the plate tectonics revolution, is that we just don’t know. The main reason for this is obvious: No one can visit there. It’s just too hot and too squeezed together to visit, even with a drill hole. Hence, everything we know is inferred by the abstraction of physical, chemical and geological observations such as the passage of seismic waves, variations in the earth’s gravity and magnetic field, and rocks that have come from great depths. It’s easier to image distant galaxies than what lies more than a few miles below our feet.

In lieu of an after-dinner drink: Are we alone in the universe? Probably not. There are hundreds of billions of galaxies in the universe, several hundred billion stars in our local galaxy, and many planets around each, yielding very high odds for extraterrestrial life. But even if there’s no life outside our solar syustem, then perhaps it’s on Mars, where there is compelling evidence that shallow and potentially life-generating seas of liquid water were present. Someday, maybe soon, we’ll find out if we’re not alone.

Ignorance is delicious. Burp.