Category: experiment

5 Things We Know About Dark Matter (And 5 We Don’t)

“It’s possible we’ll get an announcement of a candidate dark matter particle at any point from a variety of experiments, but it’s also possible that the ways in which we’re presently looking for dark matter will never bear fruit. Nevertheless, we not only know that dark matter exists from the astrophysical evidence, but we’ve definitively uncovered a large amount of information about what it is, how it behaves, and what it cannot be. In the quest to understand our Universe, one thing stands out above all others: we must be intellectually scrupulous and honest about what we know, what we don’t, and what remains uncertain.”

There’s always a lot of buzz about dark matter, but most of it is misinformation either from zealots eager to dismiss it or theorists clamoring for people to latch onto their latest wild (and unsupported) idea. But the real scientific truth is that we are absolutely certain that dark matter (or something very, very much like it) is present, and has properties that we can test for and measure in astrophysical environments. But it’s simultaneously true that there are a number of open questions about dark matter that we don’t have the first clue what the answer will turn out to be, and must remain open to the possibilities.

Here’s a great list of five things we actually know about dark matter (plus how we know it), along with five things that still remain obscure to us all.

Are Physicists Too Dismissive When Experiments Give Unexpected Results?

“Whenever you do a real, bona fide experiment, it’s important that you don’t bias yourself towards getting whatever result you anticipate. You’ll want to be as responsible as possible, doing everything you can to calibrate your instruments properly and understand all of your sources of error and uncertainty, but in the end, you have to report your results honestly, regardless of what you see.

There should be no penalty to collaborations for coming up with results that aren’t borne out by later experiments; the OPERA, ATLAS, and CMS collaborations in particular did admirable jobs in releasing their data with all the appropriate caveats. When the first hints of an anomaly arrive, unless there is a particularly glaring flaw with the experiment (or the experimenters), there is no way to know whether it’s an experimental flaw, evidence for an unseen component, or the harbinger of a new set of physical laws. Only with more, better, and independent scientific data can we hope to solve the puzzle.”

On the one hand, when experiments don’t agree with theoretical predictions, it offers the fascinating possibility that perhaps we’re about to learn something new about the Universe, perhaps even something big and revolutionary. But on the other hand, most times that experiments don’t line up with theory, it’s because there are errors and flaws with either the experiment or how the results are interpreted, not because the theory is wrong. We have a responsibility to strike the right balance, as scientists and as science communicators, in how we put these unexpected results out into the world.

Are physicists too dismissive of unexpected results? Or, quite possibly, are we not skeptical enough when we advance them to the general public? Here’s where we stand today.