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Science/Tech See other Science/Tech Articles Title: Leading Harvard physicist has a radical new theory for why humans exist Yahoo... Business Insider Where do we come from? Well, it depends on who you ask. For example, an astrophysicist might say that the chemical components of our bodies were first forged in the nuclear fires of stars. On the other hand, an evolutionary biologist might look at the similarities between our DNA and that of other primates' and conclude we evolved from apes. Lisa Randall, a theoretical physicist at Harvard University, has a different, and novel answer, which she describes in her latest book, "Dark Matter and the Dinosaurs." Randall has written other popular science books, including the New York Times bestseller "Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions." Her studies at Harvard explore theoretical particle physics and cosmology. In her latest book, she posits that the extinction of the dinosaurs — necessary for the emergence of humans — is linked to dark matter. Dark matter is the mysterious, invisible matter that astronomers estimate makes up 85% of all matter in our universe. One species' extinction is another's head start View gallery . An artistic life reconstruction of a new horned dinosaur scientists named Regaliceratops peterhewsi in the paleoenvironment of the Late Cretaceous of ... (Thomson Reuters) Paleontologists largely agree that about 66 million years ago a giant, 9-mile-long celestial body — likely a comet — struck Earth. The impact wiped out 75% of species across the planet, including most of the dinosaurs. Among the survivors were small primates. Over the next 66 million years these primates diversified, grew larger, learned to walk on two legs, and developed large brains, which they eventually used to invent pizza delivery. So what caused that giant space rock to collide with our planet in the first place and give primates a chance to thrive? It could just be chance — or luck, depending on your perspective — but Randall would disagree with both of these ideas. View gallery . dark_matter___the_dinos (Business Insider) In her book, Randall describes a dark, pancake-shaped patty of densely packed dark matter within our galaxy that could be responsible for our emergence as a species. Dark matter has never been directly detected. However, there is enough evidence for its immense gravitational influence on our universe that the vast majority of the scientific community agrees that dark matter is a form of mysterious matter that we can neither see or touch, but that nevertheless must permeate the cosmos. Generally, dark matter tends to be concentrated in large halos around galaxies like giant bubbles. But Randall thinks that there could also be a so-called dark disc amid the stars, planets, and gas clouds in our galaxy. Beware the dark disc If there is dark matter in Randall's hypothetical disc, then it stands to reason that the disc has a powerful gravitational influence on the objects around it — including our solar system. But our solar system is not always near the disc, which is the crux of Randall's theory. As the solar system revolves around the center of the Milky Way — the same way Earth revolves around the sun — it moves up and down, or oscillates, through the plane of our galaxy. And the rate of this oscillation is very intriguing. Below is an illustration of our solar system's oscillation, where the orange dot in the lower left rectangle is our sun and the black line at the center is the dark disc: View gallery . e41_2 (APS/Alan Stonebraker) A team of astronomers made a rough estimate of this oscillation rate near the turn of this century, calculating that our solar system passes through the plane of the Milky Way about once every 32 million years, which means if there's a dark disc, we pass through that at the same rate. Interestingly, there's evidence to suggest that mass extinctions in Earth's past happened within this time frame, or about once every 25 to 35 million years. It's this similarity between the mass-extinction rate and the rate of our solar system's oscillation through the galaxy that made Randall and her Harvard colleague Matthew Reece first suggest the link in scientific paper published in the journal Physical Review Letters last year, and that Randall explores more in her book. Randall hypothesizes that when we're passing through the dark disc, the gravity from the dark matter within influences the outer region of our solar system, called the Oort cloud. The Oort cloud, illustrated below just right of center, sits about two light years from the sun and is thought to contain billions of icy objects at least 12 miles wide. View gallery . PIA17046_ _Voyager_1_Goes_Interstellar (Uploaded by WolfmanSF to Wikipedia) If something 12 miles wide hit Earth today, it would mean the end of life as we know it. And Randall thinks that's exactly what happened to the dinosaurs 66 million years ago that opened the door for widespread primate evolution. Prove it View gallery . dark matter (NASA Goddard Spaceflight Center) Dark matter is illustrated here as the fog between galaxies. While it's impossible to wind back the clock, proving the existence of the dark disc would greatly advance Randall's theory. She's tried to do so by looking at the speed and direction of stars in our galaxy. If stars moved in ways that couldn't be explained by the amount of ordinary, visible matter around them, then it could suggest the presence of the dark disc. But that's a very tall order. There are about 100 billion stars in the Milky Way, and hunting dark matter is notoriously tricky. We have a dozen or so functioning detectors underground, on Earth's surface, and in space — and none of them has yet managed to sniff out a dark-matter particle. If they do, it would be a significant step toward supporting Randall's hypothesis. In her concluding remarks, Randall writes: "In some global sense, we are all descendants of Chicxulub [the town where the dinosaur-killing meteor impacted]. It's a part of our history that we should want to understand. If true, the additional wrinkle presented in this book would mean that not only was dark matter responsible for irrevocably changing our world, but also that some of it played a crucial role in allowing our existence." NOW WATCH: Here's why aliens might actually exist finance.yahoo.com/news/le...cal-theory-160000092.html Poster Comment: richard Natural cycles have been proven in the past at various lengths of time and occurrences. My question is,if this cycle happens every thirty million years or so,what happened to the earth and its species 30 million years ago? Also,at that time,could there not have been more versions of the human species created starting in lower form of life? In other words,scientists insist on drawing a linear line of development of the human species when I believe,through time, there has been five or as many as eight variations of humans brought into existence. I am not convinced on the outcomes of results on DNA made on various specimens of ancient species. Again,that testing is biased toward the linear hypothesis but tm ,it is not conclusive6-5. David Actually, a lot of the "natural cycles" theories are still controversial, out of favor, or disproved. You'll note this theory gives itself a leeway of 25-35 million years. There was probably something happened during that time, and a theory that has nothing solid about it would probably be given a couple passes anyway. It is actually getting pretty popular with scientists nowadays to show evolution (including that of humans) as a bunch of bushes with parallel lines, lots of "twigs," etc. Neanderthals were considered to be at least in our genus even before the DNA tests. I can't think of any other lines DNA tested except for the Denisovans and maybe one or two other "archaic" members of of our genus (or possibly species). But there simply aren't any fossils to support the notion that there were many lines of human-like species outside our genus. Also, there's no indication of any fossils of anything close to humans or anthropoid apes dated older than about 10 million years ago, and I think I'm stretching a bit at that. So what exactly you mean by "more versions of the human species created starting in lower form of life" way back then... well, there could have been all sorts of prosimians and such long ago, but there's no indication that anything was becoming bipedal or especially intelligent.3 R richard ... Thanks David.Very thorough analogy. What you are saying is science has not found a definitive answer to our questions which is great because we can discuss different theories freely. Dark matter was an issue back in 1935 because Tesla did discover that energy and proved to tap into it by demonstrations of his equipment. And so it goes. 1 Marc ... It seems like you are assuming that humans were the desired result of evolution. Nothing else diverged millions of years ago to develop into humans, there is one line that at times did branched or bushed out but after enough divergence breeding would not be possible. At some point our brains became a major tool of one of our ancestors and subsequent species through nat selection improved on this eventually ending in modern humans, who knows what we will become some day. No other family has evolved the same way(heavy use of brain), others tend to use more physical ways to solve problems to their survival. The fact that we use our brain has allowed us to do all of these other things that set us apart from every other species. Jakepi3 8... Embryology shows we still have the original fundamentals of other creatures in our make up such as chickens and fish. If you were willing to spend the funds you could take the double helix back to before there were humans present and study what other possible creations existed within those spirals! Neal Everybody knows our purpose on this planet is to open cans and take care of other tasks for cats who used to be able to do all those things, but through the miracle of evolution lost their thumbs. I don't think it really matters what any of the theories are as none of our cats seem to care where we came from as long as we're around to tend to their needs real or imagined and no matter how frivolous. 2 Post Comment Private Reply Ignore Thread
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