From: Bill Gosper <billgosper@gmail.com> To: math-fun@mailman.xmission.com Sent: Fri, July 2, 2010 1:13:29 PM Subject: Re: [math-fun] Stupid antimatter questions Is this just tabloid journalism? http://www.bnl.gov/bnlweb/pubaf/pr/PR_display.asp?prID=1139 --rwg On Wed, Jun 30, 2010 at 11:27 AM, Henry Baker <hbaker1@pipeline.com <http://gosper.org/webmail/src/compose.php?send_to=hbaker1%40pipeline.com>> wrote:> "How do we know whether something we're looking at in a telescope is matter or anti-matter?" I think the main answer is that space isn't empty, and if there were a boundary between matter and antimatter anywhere we would see all the gamma rays coming from the annihilations at the boundary. There aren't many other asymmetries! --Josh _______________________________________________ The Brookhaven news release looks totally legitimate. There are asymmetries between matter and antimatter. There are experiments that can determine whether one's laboratory is made of matter or antimatter without the need for an externally supplied sample, without a preconceived notion of clockwise vs. counterclockwise, without a preconceived notion of positive vs. negative charge. In fact, there is antimatter in the universe, produced by collisions with high energy particles. The gamma rays from its annihilation present an obscuring background to the detection of primordial antimatter. -- Gene