We all are very curious about how our universe is formed. So, let’s take overview of what is exactly happened at the time of the big bang !
At some point in the past, the distance between nearest galaxies must have been zero. The entire universe was squashed into a single point. This single point is very hot, infinitely dense, only few milli-meters wide and similar to the supercharge black hole. Before 13.7 billion years ago something happens and this singularity explode. From this came matter, energy, space and time. After the explosion there were formation of two major stages of the universe. The first is Radiation Era and second is Matter Era. Let’s see them in detail.
Radiation Era
In Radiation era, there were several epochs like
- Plank Epochs
- Grand Unified Epochs
- Inflationary Epochs
- Electroweak Epochs
- Quark Epochs
- Hadron Epochs
- Lepton Epochs
- Nuclear Epochs
Plank Epochs
The first is plank epochs, formed immediately after the big bang. The temperature of the universe was 1040 K. Here no matter existed, only energy and super-forces were existed. The super-forces such as gravitational, strong nuclear, weak nuclear and electromagnetic.
Grand Unified Epochs
The next epoch is grand unified epochs. Time of this epochs after big bang is 10-43 sec having temperature of about 1036 k. In this, forces of nature were same as plank epochs.
Inflationary Epochs
10-36 sec after the big bang, inflationary epochs formed. The Temperature of the universe were 1033 k. At this stage universe starts to expand rapidly. Space is very hot at this time, produces electron, quarks and antiquarks. The elementary and fundamental particle of universe.
Quark Epochs
Quark epochs formed 10-12 sec after big bang. The temperature of the system was 1016 K. At this stage, universe got all the ingredients at present. However, it’s too hot and dense for subatomic particles to form.
Hadron Epochs
Next is hadron epochs. Time after big bang 10-6 sec and at temperature 1010 K . In this epoch universe cool down enough for quarks to form proton and neutrons.
Lepton and Nuclear Epochs
The final two epochs are lepton and nuclear. Both formed about 1 sec and 100 sec after the big bang respectively. The temperature of laptop epochs is about 1012 k where nuclear epochs having temperature about 109 k. In this epochs, proton and neutron undergo significant change. They fused and created the nucleus. Doing so, they created first chemical element in the universe -‘HELIUM’.
Matter Era
In matter era, there were three epochs.
- Atomic Epochs
- Galactic Epochs
- Steller Epochs
Atomic Epochs
After 50,000 years after big bang, temperature of the universe decreases to 3000 k. In this, universe cool down enough for electron to attack nuclei for the first time. From recombination process, helps to create 2nd element which is Hydrogen.
Galactic Epochs
Galactic epochs formed 200 Million years after big bang. The hydrogen along with helium form atomic clouds. Within clouds there is small pack of gas may hold enough gravity to collect atom. This cluster of atom form during galactic epochs became the sibling galaxies. Inside these galaxies, star begins to form.
Steller Epochs
Steller epochs formed after 3 Billion years. It’s the current stage of the universe. In this, the formation of stars causes tremendous effect to help to see universe as we know it. Heat within stars cause the conversion of helium and hydrogen in almost all the remaining elements in the universe. Those elements are building block of planet, life and everything we see today.
Big Bang Evidence
- Universal expansion and Hubble’s law
- Background radiation
- Radioactive decay
- Speed of light and stellar distance
Universal Expansion and Hubble’s Law
Hubble observed the majority of galaxies are moving away from each other. The farther away from earth, the faster they move. [ V= Hd ]. Redshift is evidence of expanding universe. It has been seen that, if star or galaxies moving away from us then their wavelengths become longer. Longer the wavelength, shorter the energy. The more the Redshift in their electromagnetic spectrum, more they moving away from us. This is one of the solid evidences for expansion of the universe.
Background Radiation
Cosmic microwave background radiation is remnant of light from big bang spreads in entire universe. The cosmic microwave background radiation (CMBR) that Penzias and Wilson observed is leftover heat radiation from the Big Bang. Today, CMBR is very cold due to expansion and cooling of the Universe. Noise radiation is evenly spread across space. C.O.B.E satellite confirmed that, for entire universe noise radiation is evenly spread. Law of conservation of energy remains constant over the time.
Radioactive Decay
Radiometric dating gives us the age of the items from the decay of radioactive materials found within the object. Moon rocks have been dated and found to be older than the earth. It gives us an estimated time that earth and moon formed. Radiometric dating of asteroid and meteorites gives us data of age of our solar system.
It is a best theory we have for the origin of our universe. However, there are still gaps. The more there is to learn, the more will questions arises.