The Big Bang is not just one theory
The full-screen image can be seen here.
- Ever since Edwin Hubble discovered that the universe is expanding, there has been a tug of war between those who provide evidence that the entire universe began as a single point at a finite time in the past and those who desperately wish to tell the opposite story, that the Big Bang never happened.
- Prior to that time, the predominant belief among scientists was that the universe was essentially static and infinite, having existed for all time. Steady state.
- Indeed, this was a primary “scientific” argument against Creation stories here that posited that the universe came into being through divine action.
- If the universe existed forever, then it did not need a creator. here
- This is hardly relevant to religion, for religion is properly unconcerned with scientific theories of the physical creation of the universe. here
- Nevertheless, many Christians latched on to the Big Bang theory as proof of creation a finite time in the past.
- Unfortunately, the Big Bang model says nothing about the birth of our universe, in the sense that time actually began then, rather it only says that at a point in the past about 13.77 Gyrs ago,
- Gaₛ=3.15581×10¹⁶ s. Byr was formerly used in English-language geology and astronomy as a unit of one billion years. Subsequently, the term gigaannum has increased in usage, with Gy or Gyr still sometimes used in English-language works. Astronomers use Gyr or Gy as an abbreviation for gigayear. source more
- the universe was in such a hot, dense state that the very laws of physics break down.
- In other words, the Big Bang is the point where we cannot, with our current knowledge, know what happened before it.
- That does not mean that it is impossible to know. Nor that we will never know. It only means that we do not have sufficient understanding to know.
- Despite attempts over the years to poke holes in the Big Bang theory, the model has been extremely robust, though not without its problems.
- Alternatives like steady-state theory in which new matter is continually created as the universe expands and the so-called plasma cosmology of Eric Learner here have failed to match the data we get from the Cosmic Microwave Background as well as other observations of the universe.
- With spacecraft such as COBE, WMAP, and the Planck spacecraft providing ever better precision observations of the universe, the Big Bang theory [ignore TV aspects] has only become stronger.
- The Big Bang is, as far as cosmology is concerned, the only game in town.
- It turns out, however, that the Big Bang theory is not exactly a theory here so much as a particular fact about the universe, that it was hot and dense at a finite point in the past.
- General relativity suggests that it was, in fact, infinitely so, although quantum theory suggests this is impossible because of uncertainty (nothing can have zero size in quantum theory). suggested that time began there. Traditional Big Bang theory here suggested that time began there.
- Indeed, Stephen Hawking proposed that the Big Bang was no more special than the North Pole [South pole actually here] is to Earth and that the idea of time having a beginning is meaningless.
- This “no-boundary” proposal was as good as any because we just had no evidence to conclude anything about what the Big Bang actually meant.
- Along with John Hartle [seems as if it is James Hartle here but ignore the row of books], Hawking’s aim was to prove that the Big Bang was more like a smooth rather than pointy feature of the four dimensional universe.
- That does not rule out other theories that do include an early hot, dense period such as Big Bounce theories where the universe collapsed in on itself before expanding out again or the Black Hole Big Bang Theory where time and space switched places inside a huge black hole, creating our Big Bang.
- Yet these are simply speculations without any real evidence to back them up.
- While inflationary theory, where the universe had an early period of rapid expansion, seemed poised to take over as the dominant theory of the Big Bang, it has turned out to be unfalsifiable because it has too many free parameters.
- Nowadays, we just don’t know how the Big Bang came about and we have no evidence about whether time began there or not.
- Theories that an anti-matter universe began at the same point proceeding in the opposite direction in time might be helpful to explain the absence of anti-matter in our universe, but there are other possible explanations for the lack of anti-matter.
- The primary question we might wish to ask of the Big Bang is whether time begins there, or, more properly, is it possible in this universe to determine what went on before if there was a before.
- Proponents of Loop Quantum Gravity have said yes, you can determine some of what went on before the Big Bang because, although the Big Bang was a hot, dense state, quantum mechanics [see More additional notes after 87] prevents it from being “infinitely hot and dense”.
- Nevertheless, others have pointed out that quantum uncertainty at that time erases much of what we would like to know about the pre-Big Bang universe.
- That uncertainty, small at the time of the Big Bang, is magnified as the universe expands until it covers the entire observable universe, making determinations of pre-Big Bang details virtually impossible.
- Even if we had a verified theory of quantum gravity, we would be limited in what we could glean about it.
- Another possibility is that time itself might have ceased to exist at the Big Bang, becoming instead lost amid the quantum foam see 69 of that period.
- Time as a universal concept ceases to exist when closed time-like loops such as wormholes allow the future to connect to the past.
- At the time of the Big Bang, such loops may have dominated the universe and thus made it impossible to know what is future and what is past.
- In that case, the notion of a “before” the Big Bang is problematic.
- We certainly can define an “after” the Big Bang from our perspective, but at the time of the Big Bang, quantum foam here here may have made space and time, past and future, ambiguous and interchangeable.
- Thus, “before” means no more than saying “left” of the Big Bang. Rather time is an emergent property of that early phase of cooling and expansion.
- Indeed, for all we know, many universes could have evolved out of the Big Bang, like spokes on a wheel. [Numerous other links included.]
- There is no requirement in Einstein’s theory of space and time that the universe evolved in a linear pattern with a distinct before and after.
- I don’t say this is necessarily true, but rather that our concept of “before” and “after” is naively based in our everyday experience.
- Who is to say that the Big Bang is not some sort of universe nursery rather than simply the start of our universe?
- This is more or less what the theory of eternal inflation says.
- Like the origins of life, the Big Bang is difficult to pin down because we only know about the one instance and cannot study it directly.
- Even the Cosmic Microwave Background only tells us about the universe 300,000 years after the Big Bang.
- Gravity wave detectors may allow us to penetrate further into the past and learn more, so there is hope.
More additional notes
What is quantum physics? Put simply, it's the physics that explains how everything works: the best description we have of the nature of the particles that make up matter and the forces with which they interact. Quantum physics underlies how atoms work, and so why chemistry and biology work as they do. source
Quantum mechanics explains how the universe works at a scale smaller than atoms. It is also called quantum physics or quantum theory. Mechanics is the part of physics that explains how things move and quantum is the Latin word for 'how much'. Quantum mechanics describes how the particles that make up atoms work. source
More items by Dr Anderson here.
No comments:
Post a Comment