Time is not absolute!. Albert Einstein is well-known for his contribution to physics and he described the Space-Time Continuum for the first time regarding how Universe works. The universe is huge, it is spread to great distance encompassing all the galaxies, supernovas, nebulas, planets, and other celestial bodies and it is expanding at an exponential rate than earlier estimated. Researchers studied the extent to which universe is expanding with the help of the Hubble Telescope for six years and found that the universe is expanding at a rate 10% more than earlier believed.
In 1925, Edward Hubble became the first scientist to prove the expansion of the universe and proposed ‘Hubble Constant’ which is the extent to which the universe is expanding through time. Soon, different space agencies and astronomers around the world started studying the expansion of the universe. NASA conducted the study on Hubble Constant two years ago and found that it is accelerating at five to nine percent than earlier believed. But recent study headed by Adam Reiss, a Nobel prize laureate stated that the Hubble constant as measured recently using high-precision techniques gave the value of 73 kilometers per second per megaparsec.
Another estimate proposed by the European Space Agency’s Planck satellite stated the Hubble constant at 67 km/s per megaparsec per 3.3 million years. In layman’s’ term, every galaxy situated 3.3 million years away from Earth is accelerating and moving apart at the speed of 67 km/s per megaparsec. Another estimate posted by Wilkinson Microwave Anisotropy Probe (NASA) gave a different value which has triggered the researchers due to huge discrepancies in the estimates recorded over a century.
Reiss stated that researchers across the world are trying to understanding why this discrepancy is being recorded. NASA has claimed that dark energy is to blame for the massive expansion of the universe and that too at different rates through time fabric. Further, dark energy is one of the major factor alleged with the expansion which is assumed to be growing or strengthening over time. Another theory is about dark radiation which is a cluster of a particle moving a speed close to that of light. These tiny subatomic particles are composed of sterile neutrinos that don’t contain any electron, proton or neutron. These subatomic particles called dark radiation are believed to be made up of a new but invisible form of matter.
The recent study by Hubble Telescope took six years to complete and three major steps were taken to measure Hubble Constant to high-precision. NASA calibrated the instruments to perform with maximum accuracy thus eliminating the possibility of error at around 2.3%. First, the Hubble Telescope calculates the distance of Cepheid stars known as Stellar Parallax Measurement. Once the required value is obtained, the telescope observes galaxies along with Type IA Supernovae and the Cepheid stars where the former emits an incredible amount of energy born out of exploding star while the latter has an immense brightness which is used as milepost markers. The third step revolves around observing the supernova in the farby galaxies on a scale of millions of years away from Earth. Finally, the scientists use the data collected and calculate it to know the value of Hubble Constant with time.