Linked Questions

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We Don't NEED Quantum Gravity because Gravity isn't Even A Force! [duplicate]

Now, I understand the motivation for quantum gravity. I honestly want to work on a theory myself. However, gravity, according to General Relativity, is not a fundamental force of nature. To me, it's ...
10
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2answers
878 views

Why does gravity need a graviton? [duplicate]

Einstein theorized that gravity is a phenomena manifested by the curvature of spacetime, in effect it IS the curvature of spacetime. If this is so, why do we need a graviton to convey the force of ...
2
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1answer
478 views

Why are gravitons needed to explain gravitational attraction in quantum gravity? [duplicate]

I've read and heard multiple times that gravity can't be explained by the current understandings of quantum physics. Wikipedia's Gravity entry briefly explains the incompatibility between general ...
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1answer
250 views

If gravity arises from the curvature of spacetime, why is there a need for gravitons? [duplicate]

If gravity arises from the curvature of space time, why is there a need for gravitons? If someone could explain this to me I would be very thankful. I dont understand why.
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1answer
109 views

What if quantum mechanics and general relativity are not connected? [duplicate]

The main objective in modern physics research is to find a way to unify quantum mechanics and general relativity thorugh a series of theoretical approaches called "quantum gravity theories" But what ...
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0answers
97 views

Gravity and graviton [duplicate]

If gravity is merely a consequence of massive bodies and the curvature of spacetime, why do we believe a graviton should exist in order to transmit gravitational forces.
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0answers
93 views

Does the existence of graviton contradict gravity being spacetime curvature? [duplicate]

Is gravity a property-curvature of space-time it's self as descriped in GR? Or the notion of 'graviton' is necessary in order to embed the 'classical GR theory' to the quantum's mechanics 'world' ...
0
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0answers
63 views

What´s the physical foundation of the assumption that the curvature of spacetime can be quantised? [duplicate]

At the moment different paths (by percentual very few people in the world) are taken to arrive (that is, if an arrival exists) at a theory that can quantise the curvature of spacetime. Considering the ...
1
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0answers
57 views

Why should we want to quantize Gravity? [duplicate]

I understand that it will be "nice" to have a quantum description of Gravity as well, just like the other 3 forces. I would like to find out what problems arise in existing theory (not counting String ...
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0answers
56 views

Unified theory of gravity [duplicate]

I have heard that a lot of times, but I have never completely understood what is a force theory unified with quantum mechanics, and also, why do we need this kind of gravitational theory to fully ...
3
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0answers
49 views

Does the universe need Quantum Gravity? [duplicate]

A lot of supporters of string theory say that it has to be right because the quantum gravity is necessary for the universe, is this true? Does the universe need quantum gravity?
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0answers
38 views

Quantum gravity: How do we know gravity operates at quantum scales? [duplicate]

Edit: An alternate angle on the original question I asked below: Would general relativity still create singularities in special cases (center of black holes) if we assumed that gravity had a lower ...
33
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5answers
3k views

Is the graviton hypothetical?

Wikipedia lists the graviton as a hypothetical particle. I wonder whether graviton is indeed hypothetical or does its existence directly follow from modern physics? Does observation of gravitational ...
32
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4answers
11k views

Why is gravity so hard to unify with the other 3 fundamental forces?

Electricity and magnetism was unified in the 19th century, and unification of electromagnetism with the weak force followed suit, bringing into play the electroweak force. I've been told that ...
26
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5answers
3k views

Is the quantization of gravity necessary for a quantum theory of gravity?

The other day in my string theory class, I asked the professor why we wanted to quantize gravity, in the sense that we want to treat the metric on space-time as a quantum field, as opposed to, for ...
11
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1answer
2k views

Why does gravity need to be quantised?

The electroweak and strong forces seem to be completely different types of forces to gravity. The latter is geometric while the former are not (as far as I'm aware!). So why should they all be ...
15
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2answers
2k views

The Reeh-Schlieder theorem and quantum geometry

There have been some very nice discussions recently centered around the question of whether gravity and the geometry and topology of the classical world we see about us, could be phenomena which ...
4
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4answers
614 views

What predictions can a quantum gravity theory make?

Some of the major challenges that heralded the need for quantum mechanics we're explaining the photo-electric effect, the double-slit experiment, and electrons behavior in semi conductors. What are ...
9
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1answer
853 views

Is a QFT in a classical curved spacetime background a self-consistent theory?

EDIT: Better rewording by Chris White: Is it possible to have a theory that treats both GR and QFT (e.g. QFT on a curved spacetime dynamically influenced by the standard QFT fields)? Is such a theory ...
9
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2answers
830 views

What are the anomalies with General Relativity?

General relativity is the current model of gravity which has not yet been disproved. Are there still any anomalies such as the problem of Mercury's orbit during Newtonian gravity period that it failed ...
6
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3answers
465 views

Why to unify gravity with the other forces if gravity isn't really a force?

As I understand, the Theory of General Relativity says that the force of gravity doesn't exist. The planets move in elliptical orbits because the spacetime is curved by the mass of the sun, not ...
7
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0answers
536 views

Can the laws of quantum mechanics be derived from a more fundamental theory? [closed]

String theory takes quantum mechanics and tries to make it compatible with gravity. If it turns out to be a theory of everything then would it explain why our world is described by the laws of quantum ...
1
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2answers
149 views

Why do black holes need a quantum mechanical description?

I read about black holes, about the Schwarzschild metric, Einstein field equations and their solution in the vacuum for a spherical body. I understood black holes are object whose gravity is enormous,...
3
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1answer
238 views

Why Shy away from non-local nature of gravitational energy/momentum?

Feel free to tear me a new one, This is something that has been bothering me a while. The very nature of attempting to write gravitational energy/momentum (called the stress energy pseudotensor), ...
2
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1answer
106 views

Can Bohr-Kramers-Slater (BKS) theory examples be generalized to prove that classical gravity is futile?

In the comment in What are the reasons to expect that gravity should be quantized? by Ron Maimon, it is mentioned that taking analogy from classical electromagnetic wave to classical grvational wave, ...
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2answers
120 views

What is the motivation for developing a “theory of everything”?

What is the reason physicists are working so hard looking for a "theory of everything" and trying to unify gravity with quantum mechanics? Historically, new theories were always developed to explain ...
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1answer
137 views

Quantum Theory as a framework for other theories of nature

We know that Quantum Theory should be considered as a framework in which all other theories/forces (Strong, Weak, EM and Gravity) exist. For example, we have the Quantum Chromodynamics, Quantum ...
2
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0answers
106 views

Is gravity quantized? [closed]

Two uncharged particles are placed in an empty universe one light year apart. In one year, they will feel each other's presence and begin attraction. We are ignoring the uncertainty principle in this ...
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0answers
96 views

I wondered what proof exist for the existence of gravitons?

It seems from my perspective that gravity is an indirect trait of matter; meaning that gravity is a trait of spacetime itself and that when matter interacts with spacetime, a bend occurs producing ...
2
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0answers
82 views

Isn't is far more likely that general relativity, and not QFT, is “wrong?” [duplicate]

At the risk/certainty of both sounding super ignorant and talking out of my arse, I have always wondered why there is some big mystery about why there are contradictions between the predictions ...