#### Transcript 幻灯片 1

Space and Time From infinite singularity to infinite galaxy Time is… • A independent variable in our lab • A period of a football game • ∆𝑑 𝑣 ? . . . Let’s see what Einstein's special relativity said about time: • • • • Time begin with the big bang End with the black hole Get faster if we travel faster May go to the future of future if we are in the future You may confuse about some of the above, before the understanding of Einstein's special relativity. Special relativity Different Frames of Reference View from the sailor Same scenario View from the other ship So, motions are relative. You can run 500m/s but only 10m/s relative to the ground. Special relativity The time is different relative to 2 observers who has different motion relative to each other. Time Dilation 3 atomic clock is put on a east-going plane, origin place and a west-going plane. After they went around the earth, one clock is quicker than the origin and another is slower. Time Dilation In the experiment, the time dilation on each plane is exactly what Einstein’s equation predicted ∆𝑡𝑚 = ∆𝑡𝑠 𝑣2 1− 2 𝑐 • ∆𝑡𝑚 - time interval of a moving observer • ∆𝑡𝑠 - time interval of a stationary observer • v - speed of the moving observer. • c - speed of light. Relativistic Momentum 𝑝= 𝑚𝑣 𝑣2 1− 2 𝑐 Based on the conservation of momentum and the time dilation equation, Einstein came up with the equation of momentum in different velocity relative to the stationary. Special relativity • Nothing can travel faster than light • Light has the speed of 3 × 108 m/s with all observers Einstein 1905 Speed of Light Nothing can get faster than the speed of light It’s experiment proved again!! Protons are accelerate to 0.99999999 speed of light Fermilab accelerator Time Travel Review the time dilation equation What if we travel at almost the speed of light? Then while we travel 1 seconds on the spaceship, the earth might has gone through many years. ∆𝑡𝑚 = But only in the future, we can have the technology to travel at high speed and go to the future of future. ∆𝑡𝑠 𝑣2 1− 2 𝑐 Mass–energy equivalence Do you still remember the nuclear bomb in Japan? How can such a big amount of energy was released by a small mass bomb? Mass–energy equivalence Einstein came up with one of the most important equation in physics. 𝐸 = 𝑚𝑐 2 Because of the huge value of c, small amount of mass can have huge amount of energy. Space-time relationship Space-time can be seen as a inverse proportion relationship The car stand still, the time goes at normal speed The car tar to move in space, the time gets slower General Relativity Newton’s theory works, but he never find the reason of gravity, because … There is no gravity General Relativity Einstein’s ideas: Einstein’s space view: Space is a fabric and matters make it warp The reason why the earth go around the sun is because the curve made by the sun. And if sun disappear, earth still remain its motion until the wave come, which is exactly the speed of light. This again, proved the theory of special relativity. General Relativity So, we can say that the thing we called Gravity is just the object's reaction to the bends on spacetime fabric. Although there is no gravity, since that we have use the term for many years and the awesome job done by newton, we will keep using it reluctantly… General Relativity Not only space, light also, is bend by gravity. It’s easy to try and demonstrate also, when eclipse happens, the stars place change a little bit when the moon completely hide the sun. General Relativity Visualization of black hole • Time stand still near black hole because the bend of it. • Even light is trapped forever and we can’t see it. • Every galaxy has a enormous blackhole General Relativity Time might begin at the big bang , or before our big bang, there is another big big bang. Einstein 1923 General Relativity • Relativity can not explain every thing and break down at Singularity. Singularity String Theory After the discover of quarks, we believe that there is a smaller particle and try to find it. And here comes the string theory Which try to define everything in the universe String Theory The idea is that, at all the end of smaller particle finding, it is actually similar type of string that form this particles. The only difference between them is the different vibrations they make. String Theory Strings are everywhere, but we just can’t see it, because it has several more dimensions. When we see a line far away, it’s a 1d shape line When we go closer and inside, we found out that it’s actually a tube and has 3 dimension on it. String Theory Right now, when we think back, string may exist in our world and we didn’t notice, or we may exist in string’s world and didn’t notice neither. String Theory Singularity Singularity has the infinite density, infinite mass and infinite gravity. It is a point and doesn’t really has a volume. Because of this special chrematistics, space and time get trapped in it and end. Quezt This is a multiple choice question. Jobs sold out all his iPhones and built a spaceship in case of 2012. Right now he is on the beautiful spaceship and traveling at 0.5c away from the earth. Another ship from Bill Gates is traveling toward Jobs at a lower speed of 0.4c Jobs throw a stone to Gates' spaceship at a speed of 3m/s What’s the speed of the message? A.B.0.1c D.0.7c c Constant box: B.Because c g=9.8m/𝑠 2 speed ofE.0.3c light is constant 8 m/s c=3× 10 C.relative 0.4c to all observer. 11 G=6.67× 10 @?!&*$%@ Quezt This is a multiple choice question. Jobs sold out all his iPhones again and built a spaceship in case of 2012. Right now he is on the beautiful spaceship and traveling at 0.5c away from the earth. Another ship from Bill Gates is traveling toward Jobs at a lower speed of 0.4c Jobs sent a hello message to Bill gates. What’s the speed of the message? A. 0.1c D.0.7c Constant box: All of them are correct. B. c E.0.3c g=9.8m/𝑠 2 Because the speed is relative to different frame of 8 m/s c=3× 10 C.reference. 0.4c 11 G=6.67× 10 @?!&*$%@ Quezt This is a multiple choice question. Jobs sold out all his iPhones again!!!!! and built a spaceship in case of Oct 2011. why is it Oct?... Siri tells him that bad things happens to him at 8 Oct, and good things happens in earth at 12 Oct, but time always has a sequence, so… He decided to launch the spaceship at 2 Oct and come back to meet good thing first. What speed relative to earth should him travel to make everything work? 0.8c A. 0.8c D.0.7c Constant box: Jobs' time interval is maximum 7 days B. 0.6c E.0.5c g=9.8m/𝑠 2 Good thing’s time interval is minimum 11 days c=3× 108 m/s C. 0.4c F. c G=6.67× 1011 @?!&*$%@ Since we know each variables in time dilation equation, we can calculate the most suitable solution Quezt This is a multiple choice question. Jobs failed eventually, because you didn’t send the answer to him as the speed of light.. Finally, 2012 came and the sun disappear, what will happen? A. As soon as it happen, gravity of the sun disappear and earth start to do uniform motion. B. After several minutes, earth start to go along a line. C. After several minutes, earth start its circular motion, just like JJ Thomson Experiment, is affected by the electric field in the solar system. D. As soon as it happen, gravity of the sun disappear and earth slowly stopped its spinning. Constant box: B Gravity can not be faster than light. g=9.8m/𝑠 2 c=3× 108 m/s G=6.67× 1011 @?!&*$%@ Quezt This is a multiple choice question. Based on string theory and it’s dimensions Choose the right one. A. String is the basic of particles, vibration differentiate them. B. Particles form different materials by the vibration of strings which is not only man-made string, but also anything that can vibrate. C. String theory explained singularity and the beginning of time, and illustrate how singularity is massless before the big bang. D. String is in extra dimensions because when we see a string, we may think it’s a line, but actually it may consist a bunch of string , it just too thin that we can not find out about it. A Review the notes. Constant box: g=9.8m/𝑠 2 c=3× 108 m/s G=6.67× 1011 @?!&*$%@ Bibliography and further reading http://www.perimeterinstitute.ca/in dex.php?lang=en http://en.wikipedia.org/wiki/Special _relativity http://en.wikipedia.org/wiki/Genera l_relativity http://en.wikipedia.org/wiki/Albert_ Einstein http://en.wikipedia.org/wiki/String_ theory http://www.youtube.com/watch?v= xvZfx7iwq94