Extra Dimensions

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Extra Dimensions

• By Stephen Fennington, Mikhail Kuchuk, and Suhas
  Sreeharshan

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Kaluza-Klein Theory

• The first theory to introduce extra dimensions
  was the Kaluza-Klein theory, which was first
  published by Theodor Kaluza in 1921. Kaluza
  extended general relativity into 5-dimensional
  space-time.
• In 1926, Oskar Klein proposed that the fourth
  spatial dimension is curled up in a circle of
  very small radius, so that a particle moving a
  short distance along that axis would return to
  where it began.1
• 1http//en.wikipedia.org/wiki/Kaluza-Klein_theory

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Superstring Theory

• Most promising candidatefor combining quantum
  mechanics and gravity.1
• String theory requires ten dimensions! Seven more
  than we are used to dealing with.
• There are seven tiny curled up dimensions in
  every point in space.
• 1 Warped Passages

String theory basically postulates that particles
aren't points but actually tiny vibrating
strings.
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How can there be more spatial dimensions?

• Extra dimensions may be hard to visualize but
  their properties can be determined
  mathematically.

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If there are other dimensions, where are they?

• Theoretical physicists have speculated that
  there might be additional spatial dimensions that
  escape our notice because they are too small.1
• Each of these dimensions are less than 10-33 cm.
  One tenth of a millionth of a trillionth of a
  centimeter. This is known as the Planck length.
  
• A piece of paper looks like it only has length
  and width as a string appears only to have
  length. We over look their depth because it is so
  small in comparison.
• 1 Warped Passages

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How can we detect these extra dimensions?

• The curled up dimension of the Kaluza-Klein
  universe isso small that any variation within it
  is almost imperceptible.1
• Using very sensitive equipment, physicists can
  check for violations of conservation of energy
  due to energy leaking into other dimensions.
• Similarly they can test for fluctuations in the
  gravitational force over very small distances.
• 1 Warped Passages
• 2 The Quantum Universe

• The extra dimensions are microscopic, in which
  case high-energy particle accelerators and cosmic
  ray experiments are the only ways to detect their
  physical effects.2

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Kaluza-Klein Particles

• Kaluza-Klein particles are particles that travel
  through higher dimensional space and carry
  extra-dimensional momentum.
• If we were to detect them in our regular 4
  dimensional space-time, they would carry the
  charge of familiar particles with heavier masses.
  
• Physicists can examine the properties of
  Kaluza-Klein particles to determine the nature of
  high dimensional space.

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Do Extra Dimensions really exist?

• As of yet, no experiments have proven that extra
  dimensions exist.
• This is in part because of the tiny size of the
  extra dimensions.
• The Planck length size of the curled up
  dimensions is so small that it would take
  enormous energy to see them directly, beyond the
  reach of current accelerators

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A ray of hope!

• The LHC will have direct sensitivity to extra
  dimensions 10 billion times smaller than the size
  of an atom. A Linear Collider would determine the
  number, size and shape of extra dimensions
  through their small effects on particle masses
  and interactions.

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Why should we care about extra dimensions?

• String theory requires 10 dimensions and is the
  most promising candidate for unifying all the
  forces in one model.
• Heavy particles proposed by string theory may be
  the elusive dark matter particles.
• Particle physics seeks to know if dark energy,
  dark matter and cosmic inflation are affected by
  the physics of extra dimensions.1
• 1 Quantum Universe

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Thats it for 10 dimensions!!

• THE END

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References

• DOE/NSF. Quantum Universe The Revolution in 21st
  Century Particle Physics.
• Kaluza-Klein Theory. http//en.wikipedia.org/wiki/
  Kaluza-Klein_Theory. 2/26/2007
• Randall, Lisa (2005). Warped Passages. New York
  Harper Collins
• String Theory. http//en.wikipedia.org/wiki/String
  _theory 2/26/2007