Somehow we've transitioned from the Big Bang to black holes, but the same principles apply.
General relativity is a classical field theory that describes space and time through a gravitational field. Field theories propose that matter interacts with a field, such as a gravitational field or electric field, instead of interacting directly with other matter. General relativity is classical in the sense that it does not account for quantum mechanical effects; therefore, we might expect that general relativity does not apply (breaks down) in the realm of subatomic particles or minuscule time scales. The black hole singularity appears because we're applying general relativity in a realm where quantum mechanical effects are present. There is no physical evidence that supports the singularity and the current state of research involves building a theory of general relativity that includes quantum mechanical effects so that the theory does not produce a singularity.
we made that transition because you asked me to describe how they are applied practically
"There is no physical evidence that supports the singularity"
you are disagreeing with probably the most famous physicist alive in our era stephen hawking
"However, the expansion of the universe, is like the time reverse of the collapse of a star. I therefore want to show you, that observational evidence indicates the universe contains sufficient matter, that it is like the time reverse of a black hole, and so contains a singularity."
despite that... i agree with you, most of the discussion on this is speculative and distinguished people in the field appear to disagree on this a lot, which was my argument to begin with
You took that quote out of context. Here is the whole paragraph:
"This possibility, that the galaxies would have missed each other, was supported by a paper by two Russians. They claimed that there would be no singularities in a solution of the field equations of general relativity, which was fully general, in the sense that it didn't have any exact symmetry. However, their claim was proved wrong, by a number of theorems by Roger Penrose and myself. These showed that general relativity predicted singularities, whenever more than a certain amount of mass was present in a region. The first theorems were designed to show that time came to an end, inside a black hole, formed by the collapse of a star. However, the expansion of the universe, is like the time reverse of the collapse of a star. I therefore want to show you, that observational evidence indicates the universe contains sufficient matter, that it is like the time reverse of a black hole, and so contains a singularity. "
Hawking is rebutting a claim that general relativity does not predict singularities. He claims that with a sufficient amount of matter, general relativity will produce a singularity. He says nothing about the physical existence of the singularity. In a later paragraph he states:
"The no boundary proposal, predicts that the universe would start at a single point, like the North Pole of the Earth. But this point wouldn't be a singularity, like the Big Bang. Instead, it would be an ordinary point of space and time, like the North Pole is an ordinary point on the Earth, or so I'm told. I have not been there myself. "
Hawking is discussing his no boundary theorem (Hartle-Hawking State) in which the universe transitions between imaginary time and real time. Like other researchers, Hawking is attempting to build a theory that does not result in a singularity.
Even in a more recent lecture "The Origin of Universe" (2005) found on the same site, Hawking states:
"Although the singularity theorems of Penrose and myself, predicted that the universe had a beginning, they didn't say how it had begun. The equations of General Relativity would break down at the singularity. Thus Einstein's theory cannot predict how the universe will begin, but only how it will evolve once it has begun. There are two attitudes one can take to the results of Penrose and myself. One is to that God chose how the universe began for reasons we could not understand. This was the view of Pope John Paul. At a conference on cosmology in the Vatican, the Pope told the delegates that it was OK to study the universe after it began, but they should not inquire into the beginning itself, because that was the moment of creation, and the work of God. I was glad he didn't realize I had presented a paper at the conference suggesting how the universe began. I didn't fancy the thought of being handed over to the Inquisition, like Galileo.
The other interpretation of our results, which is favored by most scientists, is that it indicates that the General Theory of Relativity breaks down in the very strong gravitational fields in the early universe. It has to be replaced by a more complete theory. One would expect this anyway, because General Relativity does not take account of the small scale structure of matter, which is governed by quantum theory. This does not matter normally, because the scale of the universe is enormous compared to the microscopic scales of quantum theory. But when the universe is the Planck size, a billion trillion trillionth of a centimeter, the two scales are the same, and quantum theory has to be taken into account. "
You've attempted to list singularities as support for your claim that science involves faith. I'm telling you, with the utmost respect, that you're fundamentally misunderstanding the existence and purpose of singularities. I appreciate that you're questioning science - it's a quality that I wish more people possessed - but at some point you need to realize that you're selectively reading and quoting these articles out of context to fit your narrative.
Last edited by pleaserecycle - on 16 January 2018