ORIGIN OF THE UNIVERSE 🌌🌌

 

Now, a days we are very confused about that "our origin", our origin means the origin of universe. we are just hypothetically think about that , because if we have time machine than we go and saw very easily that how our universe is started and what is its "origin of the universe" so, we can only do the hypothetical thinking it is very sad news   but its true.

                         we are just hypothetically thinked about that and do some tests, to find the answer of our question, but we havn't reached the aim.  

Hubble's hypothesis

In the late 1920s the American astronomer Edwin Hubble made a very interesting and important discovery. Hubble made observations that he interpreted as showing that distant stars and galaxies are receding from Earth in every direction. Moreover, the velocities of recession increase in proportion with distance, a discovery that has been confirmed by numerous and repeated measurements since Hubble's time. The implication of these findings is that the universe is expanding.

              Hubble's hypothesis of an expanding universe leads to certain deductions. One is that the universe was more condensed at a previous time. From this deduction came the suggestion that all the currently observed matter and energy in the universe were initially condensed in a very small and infinitely hot mass. A huge explosion, known as the Big Bang, then sent matter and energy expanding in all directions.

The Big Bang Hypothesis

This Big Bang hypothesis led to more testable deductions. One such deduction was that the temperature in deep space today should be several degrees above absolute zero. Observations showed this deduction to be correct. In fact, the Cosmic Microwave Background Explorer (COBE) satellite launched in 1991 confirmed that the background radiation field has exactly the spectrum predicted by a Big Bang origin for the universe.

As the universe expanded, according to current scientific understanding, matter collected into clouds that began to condense and rotate, forming the forerunners of galaxies. Within galaxies, including our own Milky Way galaxy, changes in pressure caused gas and dust to form distinct clouds. In some of these clouds, where there was sufficient mass and the right forces, gravitational attraction caused the cloud to collapse. If the mass of material in the cloud was sufficiently compressed, nuclear reactions began and a star was born.

Some proportion of stars, including our sun, formed in the middle of a flattened spinning disk of material. In the case of our sun, the gas and dust within this disk collided and aggregated into small grains, and the grains formed into larger bodies called planetesimals ("very small planets"), some of which reached diameters of several hundred kilometers. In successive stages these planetesimals coalesced into the nine planets and their numerous satellites. The rocky planets, including Earth, were near the sun, and the gaseous planets were in more distant orbits.

The ages of the universe, our galaxy, the solar system, and Earth can be estimated using modem scientific methods. The age of the universe can be derived from the observed relationship between the velocities of and the distances separating the galaxies. The velocities of distant galaxies can be measured very accurately, but the measurement of distances is more uncertain. Over the past few decades, measurements of the Hubble expansion have led to estimated ages for the universe of between 7 billion and 20 billion years, with the most recent and best measurements within the range of 10 billion to 15 billion years.

Age of the milky way galaxy

Now, it is the time to end this with the last but not least topic which is the age of milkyway.

                            If you were going to throw a birthday party for the Milky Way, how many candles would you put on the cake? What is the age of the Milky Way? Well, even though this is a difficult question to answer, either way you slice the cake you need a lot of candles. If you were to put a candle for each year the Milky way has aged, then you’d need between 10 and 13.6 billion candles. That would be mighty difficult to blow out all in one go.

The oldest stars in the Milky Way are 13.4 billion years, give or take 800 million years. This is somewhat close to what the age of the Universe is (which hovers around 13.7 billion years). By measuring the age of these stars, and then calculating the interval between their formation and the death of the previous generation of stars, we can come to an approximate age of the Milky Way as 13.6 billion years. 

The age of the Milky Way is determined by measuring the amount of beryllium present in some of the oldest known stars in the Milky Way. Hydrogen, helium and lithium were all present right after the Big Bang, while heavier elements are produced in the interiors of stars and dispersed via supernovae. Beryllium-9, however, is produced by collisions of cosmic rays with heavier element.

Since beryllium is formed in this way, and not in supernovae, it can act as a “cosmic clock” of sorts. The longer the duration between the first stars that created heavier elements and the stars that make up globular clusters in the early Milky Way, the more beryllium there should be from the exposure to galactic cosmic rays. By measuring the beryllium content of the oldest stars in the Milky Way, the age of the Milky Way can be approximated.

This method is kind of like using radioactive decay of carbon-14 on Earth to determine the age of fossils. Radioactive decay of uranium -  238 and thoriun - 232 gives an age of the Milky Way as similar to that of measuring the abundance of beryllium.

The age of the Milky Way is a tricky question to answer, though, because we can say that the oldest stars are 13.4 billion years old but the galaxy as we know it today still had to form out of globular clusters and dwarf elliptical galaxies in an elegant gravitational dance. If you want to define the age of the Milky Way as the formation of the galactic disk, our galaxy would be much younger. The galactic disk is not thought to have formed until about 10 – 12 billion years ago.

here is an blog to know introduction of universe which is also written by me and please comment how is my blog and give my some feedback to improve my content. "https://knowingtheuniversektu.blogspot.com/2021/06/what-and-how-much-we-know-about-universe.html"

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