![]() But in 2018, an influential paper suggested that not a single one of these myriad hypothetical universes looked like our cosmos specifically, each lacked a description of dark energy as we currently understand it. This multiverse landscape seemed to provide enough possibilities that, should researchers explore them, they would come across one that corresponded to our own version of reality. The most recent challenges to string theory have come from the framework itself, which predicts the existence of a potentially huge number of unique universes, as many as 10^500 (that's the number 1 followed by 500 zeroes). "Are you chasing a ghost, or is the collection of you just too stupid to figure this out?" teased Neil deGrasse Tyson, director of the museum's Hayden Planetarium, who pointed out that progress on string theory had been patchy in the previous years. In 2011, physicists gathered at the American Museum of Natural History for the 11th annual Isaac Asimov Memorial Debate, to discuss whether it made sense to turn to string theory as a viable description of reality. Most of its predictions are untestable with current technology, and many researchers have wondered if they're going down a never-ending rabbit hole. A never-ending pursuitīut string theory has lately come under greater scrutiny. Some scientists have even attempted to use string theory to get a handle on dark energy, the mysterious force accelerating the expansion of space and time. Researchers have used string theory to try to answer fundamental questions about the universe, such as what goes on inside a black hole, or to simulate cosmic processes like the Big Bang. They've simply described how the extra dimensions are all curled up in an extremely tiny space, on the order of 10^-33 centimeters, which is small enough that we can't normally detect them, according to NASA. That the theory bizarrely requires 11 dimensions to work - rather than the three of space and one of time we normally experience - has not dissuaded physicists who advocate it. It may be possible to detect cosmic strings with gravitational radiation (once we can detect that, which hopefully is in the next decade or so) and the cosmic microwave background, which people are already looking at.The theory explains gravity via a particular vibrating string whose properties correspond to that of the hypothetical graviton, a quantum mechanical particle that would carry the gravitational force. ![]() They can either be due to some kind of new physics like string theory, or formed for example when two regions of expanding space that have differently pointed magnetic fields meet, and there's a topological defect where the two fields can't merge. Cosmic strings are topological defects in the universe. In crystals, they could be a point where two different lattices of atoms meet and can't merge. ![]() That's an example of a topological defect. ![]() You can loosen the knot and push it around and move it along the string, but there's nothing you can do to get rid of the knot without cutting the rope. Imagine you have a loop of string with a knot in it. Topological defects are kind of complicated to explain, but basically they're things you can't get rid of by smoothly manipulating something. ![]()
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