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Question
1)What is big bang theory?(give every detail)
2)what is theory of relativity?
3)can time travel be possible?
4)what are black holes?
5)what are white holes?
thank you...
regards

Have you considered asking this question in smaller, more manageable chunks?  Your very first question: "1) What is big ban theory?(give every detail)" is beyond the scope of this forum since it would require you to read whole books on cosmology.  So I'm going to point you to links that, as an expert in physics, I can vouch for that they have valuable information.  I'm going to start with hyperphysics: http://hyperphysics.phy-astr.gsu.edu/hbase/astro/timlin.html and move you up to NASA http://map.gsfc.nasa.gov/universe/ and wikipedia: http://en.wikipedia.org/wiki/Physical_cosmology  That's a good start...this will take you a long time.

"2)what is theory of relativity?"  The theory of relativity is both the most simple and most maddeningly complex thing to try and wrap your brain around.  The basic ideas are the same: First, the speed of light is the same for all observers.  That part just comes from the wave equation for light, and Einstein was always right to trust the mathematics, even when other people doubted the results.  For more on that, see Dark Energy.  Second: all observers must use the same laws of physics, even if the results disagree from their perspective.  This both creates and resolves all paradoxes, it turns out.  Third: the principle of equivalence.  There are many statements, but essentially it means that gravitational acceleration and spatial acceleration are identical. For more detail, you should start with Einstein's book on relativity.  Try to get this link entirely into your browser.  Nobody put it better than the man himself:  http://books.google.com/books?id=gQ8LAAAAYAAJ&printsec=frontcover&source=gbs_ge_

"3)can time travel be possible?"  Current theory says that while it is technically possible to create a wormhole with one end moving at close to the speed of light which whips around a dense body like a black hole and comes back near the entryway, and that might make it possible to create a time machine that goes back to near the creation time of the machine, such a machine is in all practical terms out of the reach of human technology for the projectable future.  So, in short: theory yes, practical no.

"4)what are black holes?"  Black holes are dense objects (like collapsed stars) whose gravity is so high that light cannot escape them.  Ironically, they are some of the brightest observable objects in the sky (not the hole itself, the disk of ultra-hot gas around it known as the accretion disk).  Space becomes like time inside a black hole, and objects can move only towards the center inside.  Moving out of a black hole becomes like moving against time, the intense gravitational pull simply won't allow it.

"4)what are white holes?"  There are no objects which definitively match this description in standard physics, so I'll point you to the extremely speculative wikipedia page: http://en.wikipedia.org/wiki/White_hole  In my opinion, there are no such things as "white holes."  It's just a mathematical idea that someone came up with.  Until we know if antimatter gravitates normally, however (experiments are under way in this regard), we won't know for sure.

Physics

Volunteer

#### Dr. Stephen O. Nelson

##### Expertise

I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

##### Experience

I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Education/Credentials
Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.