It's not like you see the effect once in a while but then it disappears. In other words, data for the existence of dark matter is prevalent. There are literally thousands of studies now of those rotating-too-fast galaxies out there - and they all get the same, quite noticeable result. The answer is data, its prevalence and its stability. So how do physicists and astronomers get away with claiming the existence of cosmic ghosts (dark matter and dark energy) when they would probably roll their eyes at descriptions of the more terrestrial haunted-house kind? In this case, dark energy was made accountable for nature's heavy foot on the cosmic gas pedal. Once again, a form of invisible stuff was invoked to explain the motions of the visible stuff. Kind of sounds like those ghostly kitchen drawers doesn't it?ĭark energy was discovered 16 years ago, when observations showed the expansion of the universe (known since Edwin Hubble in the 1920s) was accelerating. Rubin and others reasoned there had to be a giant sphere of invisible stuff surrounding the stars in these galaxies, tugging on them and speeding up their orbits around the galaxy's center. It was Vera Rubin's famous work in the 1970s that showed pretty much all spiral galaxies were spinning way too fast to be accounted for by the gravitational pull of the their "luminous" matter (the stuff we see in a telescope). This means they go bump in the night with stuff we can see in different ways.ĭark matter was discovered decades before dark energy by looking at how galaxies rotate. It's important to understand that dark matter and dark energy are different "things," in the sense we've inferred their existence through different kinds of phenomena. You can't see the dark matter and dark energy - but you know it's with you because it messes with the things you can see. Well, basically, they mean the dark stuff acts a lot like a ghost in a horror movie. But what exactly do physicists mean when they talk about something being "dark?" Over the last few decades, scientists have built a new picture of the universe where about 95 percent of its stuff comes in a "dark" form (27 percent being dark matter and 68 percent being dark energy). But after attending a recent lecture on the "dark universe," I got to thinking: How are we physicists different from anyone else telling ghost stories? Most scientists, myself included, are pretty skeptical of ghost stories. You can't "see" the ghost, but you know it's there. When I poked around looking for "real ghost stories," I found many accounts like the classic scene described above. In that same poll, almost 30 percent of the respondents said they believed that they'd personally been in the presence of a ghost. A minute later he comes back in - and everything's open again.Īccording to a Harris poll in 2013, about 45 percent of people believe in ghosts. So, he closes all the doors and all the drawers and walks out. It usually comes early in the story, like in The Sixth Sense: The protagonist walks into a room, like the kitchen, and all the cabinets and drawers are open. Every ghostly horror movie has "the scene."
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