Sunday, January 17, 2010


1. What are the fundamental particles of all known matter as far as we know?
electrons, quarks

2. What are the four fundamental forces? Which ones are currently part of a single theory, and how are those forces unified?
Strong, Weak, Electromagnetic, Gravity. All but Gravity are part of Quantum mechanics by which each force is transmitted by a particle (a boson)

3. What are some of the ideas involved in Quantum mechanics. Explain any or all of these to the best of your ability.
Quantization, uncertainty principle, wave-particle duality, force carrying particles.

4. What is the difference between special relativity and general relativity?
Special relativity refers to observers in uniform motion whereas general relativity compensates for accelerated motion as well; it is general relativity that describes gravity.

5. What does relativity imply about how gravity works?
By general relativity, space and time are warped by mass and energy giving the effect of gravity.

6. What is a string?
A string is a theoretical fundamental object. It is proposed that every fundamental particle in the standard model is a vibrational mode of a string vibrating in ten dimensions.

7. What are three of the problems in modern physics that string theory may solve.
See lecture 2 for a list.

8. What are some of the reasons we may not be aware of extra dimensions?
Small/ curled up/ branes/ warped geometry

9. Why would gravity not be confined to a brane?
Relativity says that gravity should take place in all dimensions of space and time; also gravitons, the theoretical force particle corresponding to gravity, are given by closed strings which would not be trapped on a brane as open strings are.

10. What is supersymmetry?
Supersymmetry is a symmetrical theory by which bosons (integer spin /force carrying particles) have supersymmetric partner particles that are fermions (half-integer spin/ matter particles) that can be exchanged. Supersymmetry is an important part of string theory. It's necessary if string theory is to replicate the known universe.

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