If you're running very fast, say at or near the speed of light, can you see behind you?
I am enjoying more and more my classes. I feel that the hard work I've put into physics so far is beginning to take some effect. Things are slowly coming together. All the branches are sort of becoming clearer, and I can see more precisely where the connections are. There's still a long way to go, and it doesn't look any easier, but, steady ho!
In relation to physics, the department picnic was this Sunday. Our class was in charge of getting things together, bbq-ing the pounds of burgers and hot dogs (220!) we bought. It was a genuinely fun and good time. I personally enjoyed cooking; I was at the grill all day. Somehow I could feel the chef in me surface. I suppose I may have a potential career as a professional chef! Or at the least, I'm pretty good at bbq. The weather also looked kindly upon us. The downpour began the minute we all finished cleaning up and hopped into our cars to drive away from the camp site. Really! It was like, wow, there is a higher divine power, and He was on our side today. I suppose I feel He's on my side every day, which is why I feel so blessed and optimistic much of the time. Sounding too Christian here heh (I'm not Christian).
Speaking of the higher power, there's a Chinese saying that "a day in heaven, is like a year on earth." This is the principle of relativity! We've come full circle back to the beginning of the blog. I suppose this statement is related to the famous Traveling Twin example. Suppose a twin leaves earth on a spaceship moving at constant velocity away from the earth. Her twin brother remains on earth. When the traveling twin returns, who's younger? The answer, is the traveling twin has aged slower, because to return, there is some interval of time where she is not in an inertial reference frame, ie not moving at constant velocity with respect to earth. This conveniently solves the dilemma of "But what if I assume the twin on earth is moving away in the other direction at constant velocity from the twin on the spaceship?" The deceleration and acceleration of the twin on the spaceship makes a difference! On her way back, she reaches some constant velocity traveling toward earth, thus, she is now in an inertial ref system. But this is different from the system on her way out. Thus, her switching inertial reference frames requires readjusting her clocks---this leads to her conclusion that her brother is older.
What really happens is that we see the geometry of spacetime is no longer our usual Euclidean space, where we expect the straight path of travel to take the shortest time. Spacetime is governed by the rules of Minkowski space, and in fact, the straight path takes a longer time to travel then others that share the same endpoints!
I am enjoying more and more my classes. I feel that the hard work I've put into physics so far is beginning to take some effect. Things are slowly coming together. All the branches are sort of becoming clearer, and I can see more precisely where the connections are. There's still a long way to go, and it doesn't look any easier, but, steady ho!
In relation to physics, the department picnic was this Sunday. Our class was in charge of getting things together, bbq-ing the pounds of burgers and hot dogs (220!) we bought. It was a genuinely fun and good time. I personally enjoyed cooking; I was at the grill all day. Somehow I could feel the chef in me surface. I suppose I may have a potential career as a professional chef! Or at the least, I'm pretty good at bbq. The weather also looked kindly upon us. The downpour began the minute we all finished cleaning up and hopped into our cars to drive away from the camp site. Really! It was like, wow, there is a higher divine power, and He was on our side today. I suppose I feel He's on my side every day, which is why I feel so blessed and optimistic much of the time. Sounding too Christian here heh (I'm not Christian).
Speaking of the higher power, there's a Chinese saying that "a day in heaven, is like a year on earth." This is the principle of relativity! We've come full circle back to the beginning of the blog. I suppose this statement is related to the famous Traveling Twin example. Suppose a twin leaves earth on a spaceship moving at constant velocity away from the earth. Her twin brother remains on earth. When the traveling twin returns, who's younger? The answer, is the traveling twin has aged slower, because to return, there is some interval of time where she is not in an inertial reference frame, ie not moving at constant velocity with respect to earth. This conveniently solves the dilemma of "But what if I assume the twin on earth is moving away in the other direction at constant velocity from the twin on the spaceship?" The deceleration and acceleration of the twin on the spaceship makes a difference! On her way back, she reaches some constant velocity traveling toward earth, thus, she is now in an inertial ref system. But this is different from the system on her way out. Thus, her switching inertial reference frames requires readjusting her clocks---this leads to her conclusion that her brother is older.
What really happens is that we see the geometry of spacetime is no longer our usual Euclidean space, where we expect the straight path of travel to take the shortest time. Spacetime is governed by the rules of Minkowski space, and in fact, the straight path takes a longer time to travel then others that share the same endpoints!
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