Neil DeGrasse Tyson- On Big Bang Theory

but before I begin let me remind you that if you look throughout cultures and throughout time people if you look at their writings have always wondered how things began origins question of origins seems to be perhaps even genetically encoded in our capacity to ask questions so it's there people want to know and it turns out the 20th century was the very first time in history where we were able to bring the methods and tools of science to answer that question all previous times and all previous cultures had no greater tools than simply the mythology of their imagination and so we do live in special times because we don't we're not relegated to just having to imagine how things begin we can look out with our largest telescopes probe exotic states of matter with our particle accelerators and come to terms with how the universe began how it evolved and how it land and so let's explore the evidence for the Big Bang let me begin by saying what could possibly force a rational astrophysicist to believe that all the matter energy space and time of the universe began 13 billion years ago packed into a primeval fireball smaller than some infinitesimal fraction of the size of the point of a pin and it's been expanding ever since what could possibly bring someone to believe that well answer simple regardless of what you may have read or heard the Big Bang is supported by an overwhelming body of evidence more evidence in support of the Big Bang than any idea that has ever preceded it or any idea that has come since it's all about the evidence it's not about belief systems I've had people come up and say do you believe in the Big Bang I don't even understand the question the question properly worded would be of all the evidence that's out there what idea is best supported by that evidence it's the Big Bang now let's talk about theory if you look back in the 1900s in the 1800's excuse me in 1800s in the 1700s there were theories put forth in the world of physics that some of them were kind of radical ideas but they were finally tested and confirmed and then they got called laws laws there's the law of gravity Newton's laws of gravity Newton's laws of optics laws of motion laws of thermodynamics - the error of laws you enter the twentieth century very early in the 20th century we get to Einstein's theory of relativity the 1920s we have quantum theory we have quantum chromodynamics there all these theories we no longer use the term law and that's for a couple of reasons first these modern theories are as tested and as successful as what were previously known as laws so we could call them laws if we want it and be consistent with the naming schemes of our generations past but what happened in the 20th century is that we became to learn that whatever it is we determined to be true about the universe may only be a subset of a larger truth and we learned that with Newton's laws of gravity Newton's laws of gravity describe and laws of motion describe the environment in which Newton was comfortable where he had never seen anything move faster than a fast running horse so his laws of motion surely accommodated anything that came up in his day enter the 20th century start thinking about the speed of light high-speed motion and all all kinds of other phenomenon take place we need new theories to account for these new domains in which we're testing how the universe works and Einstein's theory of relativity does just that it's a theory of motion and of gravity and it encloses the piece of the universe described by new it doesn't discard Newton it enhances the sphere over which the laws apply so amount of times when we say law then month times we say theory it's a well-tested theory had that been the same theory around back in the 1800s they'd be calling it a law as they'd be calling the Big Bang the Big Bang law but I will remain humble in the presence of theories yet to be put forth recognizing that perhaps one day the Big Bang will be enclosed in a bigger picture a deeper understanding of how the universe works so let's also demand that if you come up with a new theory it's got to agree with the evidence and predict things that maybe you hadn't known before otherwise it's just sort of a an explanation that comes after the fact piecing piece putting pieces together without giving you new insight into how the world works for the Big Bang in particular a variety of experimental pillars support its status as the most successful theory ever put forth and I call them pillars because the thing is resting on these pillars we don't expect any more than one in a hundred thousand hydrogen atoms to be deuterium deuterium is just a version of hydrogen that has an extra Neutron in its nucleus we didn't just make this stuff up there's an unprecedented marriage of astrophysics and particle physics and a coherent picture has emerged by the application of those two disciplines and when you combine them it tells us that the galaxies velocities are real the galaxy distances are real the expanding universe is real relativity is real quantum mechanics is real the early universe was hot and the Big Bang is law

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Views: 148,363

Rating: 4.7616653 out of 5

Keywords: Science, NASA

Id: dxKgBkdOKr4

Length: 6min 45sec (405 seconds)

Published: Thu Dec 20 2012