Physicists face a philosophical quandary. Something they deeply wish to believe in does not appear to exist.What happens when your theory requires something but you can’t find it? That’s the situation with dark matter. Scientists around the world have built ultra-sensitive detectors deep in mines to look for “weakly interacting massive particles” (WIMPs) that would theoretically explain why galaxies and galaxy clusters move the way they do. Dark matter is also an essential ingredient for the leading big bang theory. But the most sensitive test ever cannot find it.Photograph of dark matter. Frame and white background provided for contrast.Experimental results from the XENON1T dark matter detector limit the effective size of dark matter particles to 4.1 x 10-47 square centimeters — one-trillionth of one-trillionth of a centimeter squared — the most stringent limit yet determined for dark matter as established by the world’s most sensitive detector.The results, presented Monday in a seminar in Italy at the Gran Sasso Underground Laboratory (LNGS), were produced using an active target volume of 1,300 kilograms of Xenon, the first search for dark matter that has monitored the equivalent of one ton of xenon for an entire year.“We now have the tightest limit for what is known as ‘the WIMP-nucleon cross section,’ which is a measure of the effective size of dark matter, or how strongly it interacts with normal matter,” said Ethan Brown, a member of the XENON Collaboration, and assistant professor of physics, applied physics, and astronomy at Rensselaer Polytechnic Institute. “With these results, we have now tested many new theoretical models of dark matter and placed the strongest constraints on these models to date.“Physicists don’t like to say that dark matter is not there. They prefer saying they have placed tighter limits on where it could be hiding. Space.com makes the same dodge. Nature is more blunt: “Dark matter detector draws a blank.”The world’s largest experiment intended to detect weakly interacting massive particles (WIMPs) has come up empty-handed after collecting data for nearly a year. XENON1T is located 1.4 kilometres underground at the Gran Sasso National Laboratory in central Italy. The experiment looks out for the tiny flashes of light that should be given off when WIMPs — a popular candidate for dark matter, which is thought to make up 85% of the Universe’s matter — collide with atoms in 1,300 kilograms of cold liquid xenon. On 28 May, researchers from the XENON1T collaboration reported at seminars held simultaneously at Gran Sasso and at CERN, Europe’s particle-physics laboratory in Geneva, Switzerland, that no such flashes were detected. The data suggest that WIMPs — if they exist — interact even more weakly with ordinary matter than previously thought.This is like saying that ‘ghosts, if they exist, are faster at escaping from our glances than previously thought.’ The hunt is in a vicious cycle:Dark matter must exist.Build a more sensitive detector.No dark matter found.Return to Step One.Any particle as small as 4.1 x 10-47 square centimeters is, for all practical purposes, non-existent. That’s almost a trillionth of a trillionth of a trillionth of a trillionth of a square centimeter! An electron (10-16 cm) is inconceivably gigantic by comparison. This doesn’t mean that the proposed particle is that small, but its “effective size” or ability to interact with normal matter makes it that small, practically speaking. WIMPs were thought to be quite large, actually (massive), but the “collisional cross section” (size of the interaction target) has now been so narrowed by this latest search that a successful collision would be like hitting a bull’s-eye on earth much smaller than an electron with a dart thrown from another galaxy. And yet these same theoretical particles are proposed to exert so much gravity that they hold galaxy clusters together and keep the big bang from disrupting the fabric of spacetime.Will physicists and cosmologists ever quit their so-far vain attempt to find the mysterious unknown stuff? Quitting would be a huge blow to modern physics. It would mean admitting that the Standard Model is incomplete or, at worst, wrong. A scientific revolution may be in the making.Update 6/02/18: Two physicists at the Harvard-Smithsonian Center for Astrophysics, one of them astronomer Avi Loeb, are assigning properties to dark matter. According to Space.com, they are speculating whether dark matter particles carry an electric charge. Perhaps they should discover the particles first. “The thought that dark matter could somehow be electrically charged seems too bizarre to be anything but science fiction,” reporter Chelsea Gohd admits. The two astronomers base their speculation on one possible interpretation from an instrument called EDGES that measured a particular absorption spectrum in the cosmic background radiation. Still, they confess, “The nature of dark matter is one of the biggest mysteries in science, and we need to use any related new data to tackle it.”We’ve been watching this hunt for years, curious to see how it turns out (e.g., 20 Jan, 2002, 23 July 2007, 9 Jan 2017; search on “dark matter” for more). We’ve used the case of the Mysterious Unknown Stuff (MUST) that must be there as a test of empiricism vs theory. So far, empiricism is winning. Don’t even ask about dark energy. That stuff is even more mysterious, and physicists don’t even have a theory of what it could possibly be. It’s like watching serious scientists in our own time trying to defend belief in ghosts (30 Aug 2016).The search recalls physicists’ vain attempts to look for phlogiston as the cause of combustion, or caloric as the carrier of heat. Those two historical non-detections of the 18th century led to scientific revolutions of their own (the oxygen theory, and the mechanical theory of heat). Some of the champions of those occult substances went to their deaths without admitting they were wrong. Are we seeing another case of it now?We cannot rule out a successful detection. Physicists did find the Higgs boson, didn’t they? Well, at these levels of constraint, any seemingly empirical results become so theory-laden, it’s difficult to ascertain whether they found a real particle or another version of the theory that they can keep believing in. Does that recall a situation in biology? Darwinism, perhaps? (Visited 627 times, 1 visits today)FacebookTwitterPinterestSave分享0
20 August 2010South Africa must work to retain the high level of community awareness and effective law enforcement that prevented an increase in human trafficking and women and child abuse during the 2010 Fifa World Cup, says Minister for Women, Children and Persons with Disabilities Noluthando Mayende-Sibiya.Mayende-Sibiya said this week that the available information indicated that the predicted upsurge in human trafficking and other forms of abuse during the World Cup never materialised.On the contrary, reports on the contingency measures put in place in all 2010 host cities indicated that children who went missing during the World Cup were reconnected with their families.“The experience of the 2010 Fifa World Cup indicates that it is possible to minimize incidents of abuse through a combination of high community awareness, social cohesion and effective social and law enforcement services,” Mayende-Sibiya said.“We need to retain the same high level of law enforcement, solidarity and the spirit of ubuntu demonstrated by our people during the World Cup.”She said her department would use the build-up to the 16 Days of Activism for No Violence against Women and Children campaign to retain community awareness on issues of trafficking and abuse.As part of Women’s Month, the government sought to tackle the various limitations affecting women’s lives in the country.“Our programme seeks to reach women of different social backgrounds in their localities,” Mayende-Sibiya said. “We have met young women from universities to discuss issues of education. We have gathered with women from various churches and prayed together for a society free of all forms of abuse of women and girls.“On Women’s Day, August 9, we gathered close to 30 000 women in East London, where they received an address from the President. We have debated issues affecting women at national Parliament and in provincial legislatures.“We have met influential women in the private sector to discuss issues of the ‘glass ceiling’ put on women.”Source: BuaNews
Get the Free eBook! Want to master cold calling? Download my free eBook! Many would have you believe that cold calling is dead, but the successful have no fear of the phone; they use it to outproduce their competitors. Download Now If you are reading this post, it means my beloved The Sales Blog is back online after being taken down by Anonymous. Apparently, they took down Go Daddy for supporting SOPA and similar anti-freedom legislation.Earlier this year Anonymous hacked Stratfor, a global intelligence company whose services I subscribed to, and stole my credit card. I’ve heard Anonymous uses your credit card to make charitable donations, but that’s not what they did with mine. They see Stratfor as helping serve forces that they oppose.A few weeks ago, Chick-fil-a managed to make it into the news by sharing their opposition to same-sex marriage. They drew a lot of opposition from people that support same-sex marriage and a lot of support for their beliefs from people that share their view. They believe they have a religious duty to oppose same-sex marriage.Because this blog is important to me, I now want to switch hosting providers. Go Daddy’s political decisions are interfering with my business decisions. They made a political decision to support SOPA, they were vocal about their support, and I believe they even threw some money behind that support. They lost a lot of customers for making that decision. Now they have to live with the consequences of that decision as businesses that want their sites to remain up come to understand that Go Daddy is a target.I have written this warning a couple times. But I’ll repeat myself since we are getting close to another Presidential election.You are free to support whatever political party or candidate appeals to you. You are also free to support whatever cause you believe deserves your support. You are even free to share your opinions with the world here on the Internet, on the back of your car, or when you are sitting across from them in meetings.But you are not free from the consequences of your decision to publicly share your politics.Some people will support your opinions. Other people may buy from you in spite of disagreeing with your opinions. But some people won’t do business with you because of your political opinions. The more political you are, the more you will offend people that don’t share your politics.No one will know your political opinions unless and until you share them. If your politics have nothing to do with what you sell, you aren’t obligated to share them. You aren’t changing anyone’s mind about their political beliefs, but you might be changing their mind about buying from you.Be political if you want to, but be thoughtful and be careful. There are people counting on you.QuestionsWhat are the risks of sharing your political opinions?What are the benefits of sharing your politics?How does advertising your politics help you make more sales?After you know your client shares your politics, is it okay to talk politics with them?