Dark energy outweighs everything else in the universe. It governs the shape and fate of the universe. Dark energy has not be explained by any physicists till date. We consider dark energy to be responsible for the expansion of our universe. The information we have today about the universe is only 4% which we have derived from our experimental observations. Rest 96% is hidden in the dark energy and dark matter which we have failed till date to study. There are many theories about dark energy that explains the expansion of the universe through dark energy. But none of them have been established as a perfect and correct theory. Here is a list of top 10 theories about Dark Energy,
Theories About Dark Energy
One of the hypothetical theories about dark energy. This hypothesis is postulated as an explanation of observation of an expanding universe. Time-varying dark energy and the “quintessence” was first introduced in a paper by Robert R. Cardwell, Rahul Dave and Paul steinhardt. Quintessence has been proposed by some physicists as a fifth fundamental force. This is the latest theory which differs from cosmological theory in which there is cosmological constant which by definition does not change. Whereas quintessence changes with time and is dynamic in nature. The idea behind this theory is that quintessence varies with time and location and that its energy density decreases over time.
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Image Credits: NASA
2. Virtual Particles
Quantum mechanics is weird. It allows the interaction of ordinary particles with virtual particles. Each concept of Newtonian physics we have learnt are shattered in quantum physics. This theory uses the idea of “Virtual” particles. The theory gives an explanation about the small bit of matter which appears for small instances and then disappears. The constant appearance and disappearance of particle release energy because the matter is converted to energy when particle disappears. Physicists explain that this is how space creates self-continuous energy which poses negative pressure on universe resulting in its expansion.
Image Credits: NASA/WMAP Science Team
3. Multiverses And The Anthropic Principle
Modern physics failed to calculate the actual value of Dark energy. This is considered to be the biggest failure of modern physics. Quantum physics could calculate only a very small value but modern physicists predict it to be around 10 raised to power 120 times. So the Anthropic principle was suggested which tells that the fundamental constants of physics and chemistry are just to support established laws and life of our universe. Whereas these constants will not be valid in some other universe. It is not impossible that in an infinite set of parallel universes, our universe happens to be the one with the correct value of dark energy to allow the formation of life.
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4. f(R) Theories
f(R) theories explain the model of the vast universe. The University of Chicago invented the formula or can be called as a theory f(R) which says that for a specific value of R the expansion of the universe can be defined and dark energy plays no role in the expansion. The theorists of the University of Chicago consider this theory valid and accordingly they consider that in the presence of strong gravitational force, extra forces of the universe should disappear. A team of experts at University have begun to take measurements of clusters to see if f(R) theory could be the correct explanation of our universe.
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5. An Exotic New Particle
The concept of particle and field has been established. Scientists have found that an electron establishes an electric field and similarly for gravitational field “graviton” is responsible. So scientists concluded that behind any type of field or force particles are responsible. Particle physicists and theorists said that the energy of a particular field must be transmitted by its force particle instead by the field itself. Hence they used the same concept to explain the dark energy and dark matter of the universe. Just like graviton is unobservable, Dark energy is also unobservable.
6. Time Dilation
Time dilation is a phenomenon that happens when the speed of the object is close to speed of light then the object experience time dilation. Edward Keprios, a professor at the University of Georgia argues that only the moving object itself undergoes time dilation. This theory means that passage of time was fast in the past. If this theory is true it would contradict with the second postulate of Einstein’s theory. This theory also implies that our theory would continue to expand due to effects of Hubble constant.
7. Einstein’s Theory of Gravity Is Wrong
Einstein’s theory of relativity states that every object in the universe is attracted to other bodies with the strength of attraction depending on the masses and the distance between the object. However, some physicists have argued that this theory is invalid and wrong and they have tried to discover new theories of gravity. In their theories, they have reversed the effect of gravity on the large scale so that object repel. But these theories do not have experimental backing like that of Einstein’s theory of gravity.
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8. A New Fundamental Force
The fundamental forces we have known so far are gravitational, electromagnetic, weak and strong forces. All these forces have different strength levels and have different boundary ranges. The theory of dark energy states that there is a fundamental force present in a universe we have failed to discover. This fundamental force can only be observed when the universe reaches up to a certain size. Physicists claim that this force acts opposite to that of gravity. This force acts on such a large scale that our observations on earth do not get affected by this force. No one exactly knows if this force is temporary or permanent.
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9. Theory Of Everything
Many astronomers believe that the search for dark energy is futile. They insist that research should be done to find “theory of everything” to solve the problem of dark energy. This theory should be able to explain all astronomical concepts of universe big objects to incredible small. Solving the problem through this way sounds logically correct, but this theory has proven impossible even for the brightest minds in physics. Normal laws of physics seem to break down at the quantum level. It is considered to be one of the best theories about Dark Energy.
Image Credits: hubblesite.org
10. A Property Of Space
This theory came from the Einstein’s theory of gravitation. The idea that “empty space” can have its own energy derived from the “cosmological constant”. Einstein’s view was that universe can come into existence from nothing and as space is increasing more energy can be consequently held within it. This would surely explain the reason behind the expansion of the universe. This theory extends to the time till the universe keeps expanding until everything would end in cold darkness.
Image Credits: NASA
These are the theories about Dark Energy. Do post your comments.