Many have proposed several apocalyptic scenarios, like the ones aforementioned above, but isn’t that just typical of us? The Universe might just well last forever, but one thing is true. We are very far from answering such questions.

The details of this process depend on the amount and type of matter in the Universe. Cold dark matter, warm dark matter, hot dark matter, and baryonic matter are the four suggested types. However, the Lambda-Cold Dark Matter model (Lambda-CDM), in which the dark matter particles moved slowly compared to the speed of light, is the considered to be the standard model of Big Bang cosmology, as it best fits the available data. To this, Edwin Hubble demonstrated using redshift measurements that galaxies were moving away from the Milky Way. What’s more, he showed that the galaxies that were farther from Earth appeared to be receding faster – a phenomena that would come to be known as Hubble’s Law. Hubble attempted to constrain the value of the expansion factor – which he estimated at 500 km/sec per Megaparsec of space (which has since been revised). Any breakthroughs in this area will likely lead to a unified theory of quantum gravitation, where scientists will finally be able to understand how gravity interacts with the three other fundamental forces of the physics – electromagnetism, weak nuclear force and strong nuclear force. This, in turn, will also help us to understand what truly happened during the earliest epochs of the Universe. Structure of the Universe: In this amount of time, with speed greater than the speed of light, the Universe gradually grew, and it still expands even to this day. There isn’t actually an answer to why the Universe is this big.Between the 2nd millennium BCE and the 2nd century CE, astronomy and astrology continued to develop and evolve. In addition to monitoring the proper motions of the planets and the movement of the constellations through the Zodiac, Greek astronomers also articulated the geocentric model of the Universe, where the Sun, planets and stars revolve around the Earth. Another popular scenario suggests that our Universe will stop expanding, and will actually reverse this process. When this happens, the Universe will re-collapse, and it will possibly lead to a reformation that will start with another Big Bang. This scenario is called the Big Crunch. These traditions are best described in the 2nd century CE mathematical and astronomical treatise, the Almagest, which was written by Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy). This treatise and the cosmological model it espoused would be considered canon by medieval European and Islamic scholars for over a thousand years to come. A comparison of the geocentric and heliocentric models of the Universe. Credit: history.ucsb.edu In brief, one aspect of quantum mechanics is that certain observations cannot be predicted absolutely. Instead, there is a range of possible observations, each with a different probability. According to the MWI, each of these possible observations corresponds to a different universe, with some or many of the interpretation's proponents suggesting that these universes are as real as ours. Suppose a six-sided die is thrown and that the result of the throw corresponds to quantum mechanics observable. All six possible ways the dice can fall correspond to six different universes. In the case of the Schrödinger's cat thought experiment, both outcomes would be "real" in at least one "world".

For example, scientists believe that about 10 -11 seconds after the Big Bang, particle energies dropped considerably. At about 10 -6 seconds, quarks and gluons combined to form baryons such as protons and neutrons, and a small excess of quarks over antiquarks led to a small excess of baryons over antibaryons. Since the universe by its definition encompasses all of space and time as we know it, NASA says it is beyond the model of the Big Bang to say what the universe is expanding into or what gave rise to the Big Bang. Although there are models that speculate about these questions, none of them have made realistically testable predictions as of yet. Ellis, George F. R. (1 August 2011). "Does the Multiverse Really Exist?". Scientific American. Vol.305, no.2. pp.38–43. Bibcode: 2011SciAm.305a..38E. doi: 10.1038/scientificamerican0811-38 . Retrieved 16 August 2011. By Classical Antiquity, the notion of a Universe that was dictated by physical laws began to emerge. Between Greek and Indian scholars, explanations for creation began to become philosophical in nature, emphasizing cause and effect rather than divine agency. The earliest examples include Thales and Anaximander, two pre-Socratic Greek scholars who argued that everything was born of a primordial form of matter.

Modern observations, which include the existence of dark energy and its influence on cosmic expansion, have led to the conclusion that more and more of the currently visible Universe will pass beyond our event horizon (i.e. the CMB, the edge of what we can see) and become invisible to us. The eventual result of this is not currently known, but “heat death” is considered a likely end point in this scenario too. Greene, Brian (24 January 2011). "A Physicist Explains Why Parallel Universes May Exist". npr.org (Interview). Interviewed by Terry Gross. Archived from the original on 13 September 2014 . Retrieved 12 September 2014. Between 1907 and 1911, Einstein began considering how Special Relativity could be applied to gravity fields – what would come to be known as the Theory of General Relativity. This culminated in 1911 with the publications of “ On the Influence of Gravitation on the Propagation of Light“, in which he predicted that time is relative to the observer and dependent on their position within a gravity field.