Purgatory

I wonder why we think we would see ourselves if we travel back in time. If I think about it there is no real concept of time. We talk about travelling back 3 seconds but what is that really? We defined time to keep track of events on earth and it is very nearly constant (or we just do not notice any changes in our definition of time). Time for everyone reading this differs slightly (in the sense that your seconds and my seconds are essentially not the same) and we know this to be undeniable true. but I digress... If I can change my position in 3D space why can I not travel in time as well? What I mean by this is why does a paradox have to exist if I move through time. I think our understanding of why things seem to move forward in "Time" is the issue. Why can we not treat time as just another dimension that we can only perceive to move forward in? If I go backwards in time why would that start to effect the future? I guess if you could move backwards in time you would be able to see every possible out come of every possible event . But the main question is that it is "you" travelling back in time and in a sense why can we not look at it as you moving in 3D space, but a little bit more complicated. It could be something that we just cannot comprehend, yet. The best time travel theory I've heard is this: If we created two wormholes connecting two points of space together. We send one of the wormholes on a spaceship travelling at the speed of light for 20 years. In theory the wormhole on the spaceship is travelling into the future "slower" than that of the wormhole that remained on earth. i,e 20 years have past on the spaceship and 200 years on earth. If the spaceship now returns to earth with the one wormhole being years ahead of the other does that quantify time travel if we move between the wormholes? Because in essence the the wormholes can be next to each other but are separated only by "time". To elaborate: if someone on the spaceship went through the wormhole they would be many years in the future on earth, and if they went back a little while later almost nothing would have happened on the spaceship. Still even with this I can see paradoxes arising... but it would be interesting to know what would really happen. Interesting topic ;p

Ah I wasnt using a function generator... dont worry about the post guys

Hey people. I have been fiddling around with PSPICE cadance student version for the past 3 hours trying to get it to simulate a transient response. I will attach a graph of what we got using an oscillioscope in the labs. With PSPICE I just cannot replicate the graph no matter what I do. Its my first time really using the program so I am relatively new to it. If anyone could help I would appreciate it a lot. This is the circuit we need to analyse and the graph we are supposed to get: If anyone could help me understand how to replicate this in PSPICE I will be very greatful. The frequency used on the oscilloscope was 1kHz.

Hi. I am struggling to understand what I am doing wrong with this equation. They ask for the general solution and then the particular solution afterwards. Given x(dy/dx) + 5y = 7x^2 , y(2)=5 => dy/dx + (5/x)y = 7x integrating factor: e^integral(5/x) = e^(5lnx) = x^5 multiply by this gives: x^5(dy/dx)+(5/x)y(x^5)= 7x^6 => Dx[(x^5)(y)]= 7x^6 integrate both sides => (x^5)(y)= x^7 + C => y(x)= x^2 + C/(x^5) (divided by x^5) ok thats the general solution Now I get the particular solution by subin in (2,5) so 5 = 4 + C/32 so C = 32 sub in and you have an answer... The answer they give is y(x)= (x+4x^-2) It makes no sense in my head.. If anyone could confirm my answer it would be appreciated.