General Relativity and Quantum Mechanics.
Einstein’s theory of relativity and Quantum Physics are the two successful and fundamental theories that governs the universe..
It is the biggest problem to combine both these theories.. At present physicists have two separate rulebooks explaining how nature works. There is General relativity, which beautifully accounts for gravity and all of the things it dominates: orbiting planets, colliding galaxies, the dynamics of the expanding universe as a whole. That’s big. Then there is quantum mechanics, which handles the other three forces – electromagnetism and the two nuclear forces. Quantum theory is extremely adept at describing what happens when a uranium atom decays, or when individual particles of light hit a solar cell..
Relativity gives nonsensical answers when you try to scale it down to quantum size, eventually descending to infinite values in its description of gravity. Likewise, quantum mechanics runs into serious trouble when you blow it up to cosmic dimensions. Quantum fields carry a certain amount of energy, even in seemingly empty space, and the amount of energy gets bigger as the fields get bigger. According to Einstein, energy and mass are equivalent (that’s the message of E=mc2), so piling up energy is exactly like piling up mass. Go big enough, and the amount of energy in the quantum fields becomes so great that it creates a black hole that causes the universe to fold in on itself…
Relativity and quantum mechanics are fundamentally different theories that have different formulations. It is not just a matter of scientific terminology; it is a clash of genuinely incompatible descriptions of reality…
When Einstein unveiled general relativity, he not only superseded Isaac Newton’s theory of gravity; he also unleashed a new way of looking at physics that led to the modern conception of the Big Bang and black holes, not to mention atomic bombs and the time adjustments essential to your phone’s GPS. Likewise, quantum mechanics did much more than reformulate James Clerk Maxwell’s textbook equations of electricity, magnetism and light. It provided the conceptual tools for the Large Hadron collider solar cells, all of modern microelectronics.
The equivalence principle which is one of the core idea of Einstein’s theory of gravity had recently been tested by scientists who reported that the theory qualified the quantum test.
In Einstein’s General theory of relativity, gravity and acceleration are one in a same. According to the equivalence principle, the gravitational mass of an object, which determines the strength of gravity’s pull, is the same as its inertial mass, which determines how much an object accelerates when given a push. As a result, two objects when dropped on Earth’s surface should accelerate at the same rate (neglecting air resistance), even if they have different masses or if they are made of different materials.
At the beginning, the first tests of the equivalence principle was Galileo’s apocryphal experiment in which he is said to have dropped weights from the Leaning Tower of Pisa. In the new study, physicists went a step further, putting atoms into a quantum superposition, in which an atom does not have a definite energy but has a combination of two dissimilar energy levels.
Quantum theory and General relativity, as we know doesn’t go well with each other.
Quantum tests of the equivalence principle explores the possible place where quantum mechanics and general relativity meet. Apart from this, there are many other theories which predict to unify these two giants from Physics world, "The Quantum Theory" and "General Relativity". Among them, String theory is the most profound candidate…
But for this particular test,
By striking rubidium atoms with lasers, scientists from Italy gave the atoms an movement and then observed how gravity acted upon them and bought them down. However to perform the test, by comparing the atoms in normal to those in a superposition state, scientist created two clouds of atoms and then studied their interaction.
Comparing the result of this test to one in which both clouds were in a normal energy state. As they reported that gravity acted in same way in both the cases. With a precision of 5 in 100 million, it seems an accurate result..This was not the first time when scientists tested the equivalence principle in atoms, comparing gravity’s effects on different types of atoms, for example. But this test is the first among them all to study superposition which is regarded to be one of the most weirdest properties of quantum mechanics.
The test provides us a hope that one day, we might be able to unify beauty of gravity and the weirdness of quantum world to make mankind’s most remarkable discovery….
So we need a theory of everything that describes all the 4 fundamental forces of nature into One equation.. For merging General relativity and quantum mechanics we develop a field in theoretical physics known as Quantum Gravity…. Quantum gravity is a field of theoretical physics that describes Gravity according to the principles of quantum mechanics, and where quantum effects cannot be ignored, such as near compact astrophysical objects where the effects of gravity are strong.
The current understanding of gravity is based on Albert Einstein’s General theory of relativity, which is formulated within the framework of classical Physics. On the other hand, the other three fundamental forces of physics are described within the framework of quantum mechanics and Quantum Field Theory, radically different formalisms for describing physical phenomena. It is sometimes argued that a quantum mechanical description of gravity is necessary on the grounds that one cannot consistently couple a classical system to a quantum one…
While a quantum theory of gravity may be needed in order to reconcile general relativity with the principles of quantum mechanics, difficulties arise when one attempts to apply the usual prescriptions of Quantum Field Theory to the force of gravity via gravitonbosons. The problem is that the theory one gets in this way is not renormalizable and therefore cannot be used to make meaningful physical predictions. As a result, theorists have taken up more radical approaches to the problem of quantum gravity, the most popular approaches being String Theory and loop Quantum Gravity.Although some quantum gravity theories, such as string theory, try to unify gravity with the other fundamental forces, others, such as loop Quantum Gravity, make no such attempt; instead, they make an effort to quantize the gravitational field while it is kept separate from the other forces….We will one day surely discover the theory of everything..
