Laser Weapons:

• Class 1 Impossibility.  They are impossible today but do not violate known laws of physics, so they might become possible someday.
• Provide discussion of laser weapon feasibility.   Cannot currently exist because we lack an appropriate portable power source and a stable lasing material.   Ray guns are possible, but must be connected to a power supply via cable.  Advances in nanotechnology provide some hope that laser weapons will become possible in the future by creating tiny power packs capable of delivering massive amounts of power.  (Physics of the Impossible, p. 41)

Parallel Worlds:

• Explore Hugh Everett’s “many worlds” idea, proposed in 1957.  Everett suggested that in an experiment like the one involving Schrodinger’s cat, the wave function does not collapse when someone looks inside the box.  Instead, since both outcomes are equally likely, the entire Universe splits, or branches.  In one branch of reality, the scientist observes a dead cat and in another branch, a living cat.  As Gribbin explains, “it isn’t so much that the Universe, or the observer, splits, but that the overall wave function, the superposition of states, has built in to itself a bifurcation at the moment in time where the measurement, or observation, is made.” (In Search of the Multiverse, p. 26).   In short, “any universe that can exist, does” (Physics of the Impossible, p. 244).
• Explain theory of “decoherence” – wherein all parallel universes are possible, but our wave function does not vibrate in unison with them anymore.
• Possibility of jumping between parallel worlds is more complex:

1. Probability of this occurring decreases with each atom in your body.  Since you possess trillions of these, you are much less likely to connect to another universe.  Explore this. (Physics of the Impossible, p. 248).
2. Gribbin, on the other hand, claims that “communication between the different branches of Everett’s Multi-verse…would be impossible, according to the same equations that describe the existence of such multiple realities…Except for one intriguing possibility…time travel.” (In Search of the Multiverse, p. 28).

• Because of Gribbin’s point here, I (Tory) will also now undertake a discussion of time travel as possible in itself and also for the purpose of jumping between parallel worlds.

Time Travel:

• Class 2 Impossibility.  Hovers near the edge of our current knowledge of physics.  Might be possible, but only millions of years in the future.
• Consistent with known laws of universe.  No matter how hard physicists try, they cannot seem to come up with any reason why it could not work.  (Physics of the Impossible, p. 242)
• Include discussion of possible methods for time travel such as wormholes.
• Also discuss paradoxes and ways of resolving them, which must include a discussion of parallel worlds/many worlds and “branches” of time.

Black Holes

For the purposes of this project, we will focus on Scharzschild black holes, which have no charge or rotation, only mass and spatial dimensions.

–       Star –> supernova explosion –> shed most gases, more than 2.5 solar masses, spacetime only slightly curved         –> gravity overwhelms forces between particles –> star shrinks dramatically and atomic particles are squeezed together (squeezed inside each other) –> curvature of spacetime becomes more pronounced, light rays are deflected from usual path, some returning to the dead star  –> more light pulled back to star, star grows rapidly darker –> all light bends back to star, black hole is formed

–       Star has fallen inside its event horizon when it has contracted so much that nothing can escape

• Event horizon = horizon in the geometry of space and time; a place disconnected from space and time, not part of our universe
• Black holes have a diameter of 30 km per 5-solar-mass

–       There are no forces in nature to support a black hole, so the gravity continues to increase, and it continues to contract

• Singularity: entire star is crushed down to a single point at which there is infinite pressure, infinite density, and infinite curvature of spacetime; every particle of the star is crushed out of existence; heart of the black hole

–       Black hole only has two parts: the singularity, surrounded by the event horizon

• Black hole is empty; does not get full of stuff that is pulled in; the stuff gets pulled in and crushed out of existence

–       Many strange effects of relativity exaggerated near a black hole

• Gravity slows down time –> time stops completely at the event horizon
• Time and space reversed –> on earth you have control over where you move in space, but not over where you move in time; in a black hole, you could move wherever you like in time, but you are pulled in only one direction in space (toward the singularity)

–       “It is important to realize that black holes eat stuff in an unforgiving, irreversible fashion.”  (Kaufmann, 1979)

The Search for Black Holes.

–       Cygnus X-1

• Discovered by x-ray satellite
• Has visible star “companion”
• Stellar winds from companion star get sucked into orbit around X-1 and then begin to spiral in towards the singularity
  • Friction between gas particles (particles moving much faster closer to singularity) creates immense amounts of heat (2 million degrees!); this is what shows up on the x-ray satellite

Einstein’s legacy

–       “There is no such thing as absolute space. There is no such thing as absolute time. Newton’s foundation for all of physics was flawed. And as for the aether: it does not exist.” (Thorne, 1994)

–       The Principle of the Absoluteness of the Speed of Light

• “Space and time must be constituted as to make the speed of  light absolutely the same in all directions, and absolutely independent of the motion of the person who measures it” (Thorne, 1994)

–       The Principle of Relativity

• “Whatever might be their nature, the laws of physics must treat all states of motion on equal footing” (Thorne, 1994)

–       “If you and I move relative to each other, what I call space must be a mixture of your space and time, and what you call space must be a mixture of my space and time.” (Thorne, 1994)

–       Black holes discovered and rejected

• Schwarzschild singularities
  • Schwarzschild geometry
    • Curved (warped) four-dimensional spacetime
    • Gravitational time dilation

–       Einstein did not believe in Schwarzschild singularities (black holes)

• Calculated that if a cluster of particles, with gravity holding them together, were squeezed to 1.5 times their critical circumference (=event horizon), particles would need to move faster than light to escape
  • Since nothing can move faster than light, these things must not exist
    • Did not account for the possibility that things do not escape (even light)
      • “If the object does get that small, then gravity necessarily overwhelms all other forces inside the object, and squeezes the object into a catastrophic implosion, which forms a black hole.” (Thorne, 1994)
        • Einstein rejected the idea of a star imploding, as did most of his colleagues
          • Black holes not taken seriously until 1960s

Sources:

Gribbin, J. (2009). In search of the multiverse: Parallel worlds, hidden dimensions, and the ultimate quest for the frontiers of reality. Hoboken, NJ: John Wiley & Sons, Inc.

Kaku, M. (2008). Physics of the impossible: A scientific exploration into the world of phasers, force fields, teleportation, and time travel. New York: Random House, Inc.

Kaufmann, W. J. III. (1979). Black Holes and Warped Spacetime. San Francisco, CA. W.H. Freeman and Company.

Thorne, K.S. (1994). Black Holes and Time Warps: Einstein’s Outrageous Legacy. New York, NY. W. W. Norton and Company.