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J. Richard Gott III (Princeton)
A simulation of what a network of cosmic strings may look like...
J. Richard Gott III from Princeton, in 1991, proposed another solution to the Einstein equations that would allow for time travel. This solution allowed for a phenomenon known as cosmic strings. Cosmic strings are a prediction by some cosmologists and are relics of the Big Bang. The width of the cosmic string is thinner than an atomic nucleus. However, they may extend for millions of light-years in length. Gotts idea was that, two cosmic strings, heading toward each other, can be used as a time machine, right before they collide. Space could contract if you were to make a trip around a pair of colliding cosmic strings. Space would shrink. You would only appear to be exceeding the speed of light, to a distant observer, thus, special relativity would not be violated. You could take a trip to the past. However, enormous amounts of energy would be required to do this. You would need strings with a weight of about 10 million billion tons per centimeter. These strings would also have to be moving in opposite directions at 99.999999996% the speed of light. However, this is possible. High energy protons have been observed reaching these velocities. That being said, cosmic strings, if they exist are rare. Colliding cosmic strings may be even rarer.
These gigantic cosmic strings would be floating in space since the time of the Big Bang. These are larger than the galaxies themselves. These are physically different than the objects of string theory (which are 1-dimensional vibrating filaments of energy at the Planck length), these relics of Big Bang cosmology.
If the theory of cosmic strings is correct, then all of the galaxies we observe around us, are the vibrations left by these ancient wiggling strings. These fantastic cosmic strings would stretch across billions of light years of space. This could explain some serious problems in cosmology. Our very existence could be owed to these cosmic strings.
Harlow Shapley
Fritz Zwicky
"Clumpiness":
Data from the Cosmic Microwave Radiation, or the "echo of the Big Bang", which shows the Universe at the age of about 300,000 years, indicated that the Big Bang was uniform in all directions. The universe was filled with an even background radiation. This was the period of time where the first atoms could form, the universe was finally cool enough. What astronomers found was that galaxies "clumped" up into strange formations. There were gigantic voids in between galaxies. Some of these voids stretched across millions of light years. This clumping began about 100 million years after the Big Bang. This was first observed by Harlow Shapely and Fritz Zwicky in 1938. However, their data was crude.
The question is, if observational astronomy tells us the universe is clumpy and the universe was perfectly smooth at 300,000 years of age, what happened?
Potential resolutions to "clumpiness of universe":
Cosmic Background Explorer
Dark matter
Cosmic strings
Cosmic Background Explorer
This was a great puzzle of astronomy until 1989. This is when the Cosmic Background Explorer (COBE) gave us the first comprehensive picture of the CMB. The goal of the COBE was too find temperature variations in the otherwise smooth CMB. The hot spots would grow into the galaxies that we see today.
The results became public in April of 1992. Reporters called it the "face of God." It was also calculated that the the perturbations in the otherwise smooth radiation were sufficient to cause the "clumpiness" is the universe that we observe today.
Dark matter
Maybe the simplest way to understand the clumpiness of the universe is to look at dark matter.
Before the 300,000 years after the Big Bang, that the cosmic microwave radiation captures, ordinary matter would have been too hot to clump. Atoms would be ripped apart by the heat. Dark matter could be the exception to this. In fact, clumping could have started much earlier than 300,000 years, if there was sufficient amounts of dark matter.
Dark matter doesn't interact with ordinary electromagnetic radiation. Thus, would not be affected. However, dark matter does interact with gravitation. That being said, there could have been clumps of dark matter just after the Big Bang.
Cosmic strings
To understand cosmic strings, we should understand what a phase transition is. Phase transitions are found in everything. They are not smooth, uniform transitions. They are abrupt events that begin with the formation of microscopic topological defects in the matter's atomic structure. These defects can grow very rapidly. Each phase transition has it's own atomic properties such as physical shapes that occur right before they are about to occur.
According to some particle physicists, when the Big Bang began to cool down, in the early universe, there was one of these defects. Subatomic particles could have began to cool into these defects. These include:
strings
walls
more complicated structures, called "textures"
These ancient cosmic strings, we say are relics of the Big Bang for this reason. Also, they can be closed loops or infinitely long. This web of entangled cosmic strings perturbs the entire universe and was formed soon after the Big Bang, if this theory is correct.
These strings would have enormous tension. These strings would vibrate and wiggle furiously. Some cosmic strings can also intersect with other cosmic strings. It was proposed in the 1980s that these cosmic strings would produce gravity waves. These gravity waves would later condense into sheetlike formations of matter.
Cosmic strings could also, if the early universe has a magnetic field, have produced a massive electric field. The cosmic strings would become superconductors themselves. These superconducting cosmic strings in the early universe could have pushed matter about, rather than attracting it. There would be irregularities in the distribution of matter anyway.
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