Quantum gravity
outwards, suggesting that a black hole merely is a ‘ rebounding star ’ . Carlo Rovelli states: ‘The bounce of a collapsing star can be very fast, if watched from down there. Seen from the outside, the process of the bounce can take billions of years.’ 12 Loop quantum gravity also predicts the cause of Hawking Radiation . Hawking Radiation is the result of fluctuations of loops caused by their uncertainty. 13 These fluctuations of the geometry of space thus cause the black hole’s event horizon to expand and contract. This movement is identical to that of atoms that experience heat. This revelation is what causes a black hole to emit heat. 14 However, Loop quantum gravity is flawed. Although it successfully illustrates 3-dimensional space and retains background independence , it is unclear whether this extends to attempting to expand spin network s to a 4-dimensional spacetime, as the mathematics used to define how the theory’s constructs evolve under time is still being developed. Additionally, loop quantum gravity leads to somewhat bizarre phenomena, such as the prediction that gamma rays should travel slightly more slowly than radio waves in a vacuum due to the higher frequency of light’s propagation through the granularity of spacetime. This was tested in 2009 by NASA’s Fermi Gamma -ray Space Telescope, checking the difference in arrival times between gamma-ray bursts from seven billion light-years away. However, the results were insufficient to suggest the prediction to be true as the difference in arrival times were miniscule, contrary to what the theory suggests. 15 This is the only experiment in which loop quantum gravity could have shown its validity. In addition to this, its self-contained development of mathematics used to describe the behaviour of these loops has prevented the extension of other fields assisting in similar research, unlike its counterpart, string theory. String theory solves the problem of integrating gravitons within a quantum framework. String theory is a far more encompassing theory than loop quantum gravity as it attempts to be a theory of everything. A theory of everything attempts to describe all physical phenomena within our universe. Thus, it is more comprehensive and all-encompassing than loop quantum gravity, as it attempts to also solve other key problems in physics, such as dark matter and energy. 16 String theory first replaces our understanding of point particles with multi-dimensional strings that are either closed or open and vibrate at varying frequencies. This theory requires up to 26 dimensions for its spacetime in order for these strings to function, which is far more than what we perceive in our universe. String t heory must attempt to ‘collapse’ these dimensions to just 4. 17 To accomplish this, M theory was created.
12 See Reality Is Not What It Seems (2017): 199-201. 13 This effect is described by Heisenberg’s uncertainty principle where not all information of particles can be known to an infinite degree of accuracy. This means that we cannot assume a true vacuum exists as there are uncertainties in the energy of the vacuum, which leads to the creation of virtual particles. 14 See An Introduction to String Theory (2011): 5-6; Covariant Loop Quantum Gravity: An elementary introduction to Quantum Gravity and Spinfoam Theory (2014): 207-209.
15 See Stanford researchers: Gamma-ray photon race ends in dead heat; Einstein wins this round . (2009) 16 See Introduction to loop quantum gravity. (2012): 4; An Introduction to String Theory (2011): 7-8. 17 See An Introduction to String Theory (2011): 8.
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