The Universe is expanding, that's something we know from the early to mid 20th century. But still today all of us are not on same page when its comes to the problem of how fast is it expanding or when will it stop its expansion.
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Diagrammatical Representation of Expanding Universe
With a question of what would happen later ?? |
Sitting on a grain size planet in the whole universe, we don't realize how can it be true. But for Astronomers who are trying to measure the universe’s expansion rate, its really exciting. They want to know how fast it is expanding. That rate is important for understanding how the universe works, knowing what its ultimate fate will be and even what it is made of, and for this purpose, scientists have made many sophisticated technological developments. After all, the prime mission of the Hubble Space Telescope when it was launched in 1990 was to help determine that expansion rate, which was later named as the Hubble constant, named for the astronomer Edwin Hubble.
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Edwin Hubble
Astronomer |
Since then evidence from Hubble Telescope and other research projects has established a reasonably precise answer for the Hubble constant: 73, in the units commonly used for this purpose. It means that two independent astronomical bodies separated by 3.26 million light-years will appear to be moving away from each other at 73 kilometers per second. Sure, there’s a margin of error, but not much as the precision taken is very high.
However recent reasearch led by Nobel laureate Adam Riess, puts the Hubble constant in the range of 72–75, as reported in a paper on January 3. Considering that as late as the 1980s astronomers argued about whether the Hubble constant was closer to 40 or 90, that’s quite an improvement in precision.
But there’s a problem with this outcome. Till now our Study of the universe suggests a way to predict what the Hubble constant could be. And that prediction gives a probable range of only 66–68. So seeing the above result, the two don't seem to be on the same page i.e. they disagree with each other.
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Graphical Representation of Expansion of Universe
Scientists believed that blue or yellow curve represented how the universe expanded. But actually it was the red curve. |
When this anomaly was first showed up a few years ago , many experts believed it was just a mirage that would fade with more precise measurement. But it still couldn't be explained with more advancement in our space technology.
It’s important because Astrophysicists and Cosmologists thought they had pretty much figured the universe out. It’s made up of a little bit of ordinary matter, a lot of some exotic “dark matter” of unknown identity, and even more of a mysterious energy permeating the vacuum of space, exerting gravitational repulsion. Remember that acceleration of the expansion rate? It implies the existence of such energy. Because nobody knows what it is, people call it “dark energy,” while suspecting that its real name is lambda, the Greek letter that stands for cosmological constant. (It’s called a constant because any part of space should possess the same amount of vacuum energy.) Dark energy contributes something like 70 percent of the total mass-energy content of the universe, various lines of evidence indicate.
Another possibility, which attracted many theorists, is the existence of a new particle, perhaps a fourth neutrino or some other relativistic (moving very rapidly) particle zipping around in the early universe.
However to prove its experimental evidence would require our technology to evolve to a much larger scale. Probably in the future we would measure it inn our Particle Collider's. But till then it just remains a hypothesis.
Other assumptions that we take into account, Dark matter, for example, is presumed to be very aloof from other forms of matter and energy. But if it interacted with radiation in the early universe, it could have an effect similar to that of relativistic particles, changing how the energy in the early universe is divided up among its components. Such a change in energy balance would alter how much the universe expands at early times, corrupting the calibrations needed to infer the current expansion rate however reconciling all this still doesn't counts with the experimental investigation.
It’s not the first time that determining the Hubble constant has provoked controversy. Edwin Hubble himself initially (in the 1930s) vastly overestimated the expansion rate. Using his rate, calculations indicated that the universe was much younger than the Earth, an obvious contradiction. Even by the 1990s, some Hubble constant estimates suggested an age for the universe of under 10 billion years, whereas many stars appeared to be several billion years older than that.
Even though all the advancements in space technologies and with much bigger eyes( i.e, Big telescopes) looking into the depth of the Universe. Hubble Constant is still not precisely determined which opens a new field for Astronomers, Cosmologists, Astrophysicists to work upon.
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