No infinite gravitation in string theory?

In summary, string theory tackles the issue of infinite gravitation in the combination of quantum mechanics and general relativity by avoiding the use of perturbation series. It does this through topological constraints on the string world sheet, which are believed to remove the infinities that arise in perturbatively quantized GR. Additionally, string theory predicts the existence of a massless spin-2 particle, the graviton, which is one of its main appeals.
  • #1
Eolill
7
0
Combining quantum mechanics with general relativity supposedly yields infinite gravitation, between the gravitons if I have understood this correctly (correct me if I'm wrong). String theory supposedly does away with this infinite gravitation -- my question is, how does it do this? Furthermore, does string theory actually predict the existence of a graviton?

Thank you. ^^
 
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  • #2
The infinities arise as a consequence of a certain mathematical tool, the perturbation series. It's like a Taylor expansion of a scattering amplitude; the small parameter is the coupling constant (Newton's constant).

Due to some properties of GR one can show that the individual terms in this series become infinite. That's uggly, but not the core of the problem. These infinities are wel-known from QFT, but there they can be removed via renormalization. One can show that this FAILS in perturbatively quantized GR.

In s.t. one expects that due to the topologically constraints for the string world sheet those infinities do not show up. As far as I know no proof to all orders exist but the s.t. community agrees that it will show up eventually.

What I don't expect is that the perturbation series as a whole (the sum) is finite. I would say that this is not due to a failure in the fundamental theory but due to the perturbation expansion. This tool is overestimated because of its successes in particle physics. In a fundamental theory with non-perturbative treatment no infinities should arise; this should be true in s.t. and it is true in other QG approaches.
 
  • #3
to answer your second question, yes one of string theory's main appeals is that it predicts the existence of a massless spin-2 particle consistent with the graviton
 

1. What is string theory and how does it relate to gravity?

String theory is a theoretical framework in physics that attempts to reconcile the theories of general relativity and quantum mechanics. It proposes that the basic building blocks of the universe are not particles, but tiny vibrating strings. These strings have different modes of vibration, which correspond to different types of particles, including gravitons, the hypothetical particles that carry the force of gravity.

2. How does string theory explain the absence of infinite gravitation?

String theory predicts that the gravitational force between two objects is not infinite, but instead decreases as the distance between them increases. This is because the strings that make up particles have a minimum length, which prevents them from collapsing into an infinitely small point. As a result, the force of gravity is limited and does not become infinite at any point.

3. What evidence supports the idea of no infinite gravitation in string theory?

String theory is a highly complex and abstract theory, and as such, there is currently no direct evidence to support the absence of infinite gravitation. However, string theory is able to resolve some of the paradoxes and inconsistencies that arise when trying to combine general relativity and quantum mechanics, which suggests that it may be a promising direction for understanding the true nature of gravity.

4. Are there any potential implications of no infinite gravitation in string theory?

The absence of infinite gravitation in string theory has significant implications for our understanding of the universe. It suggests that gravity is not a fundamental force, but rather an emergent phenomenon that arises from the interactions of strings. This could potentially lead to a deeper understanding of the fundamental laws of the universe and open up new avenues for research in theoretical physics.

5. What are the current challenges in studying and testing the concept of no infinite gravitation in string theory?

One of the main challenges in studying and testing the concept of no infinite gravitation in string theory is the highly abstract and complicated nature of the theory. It also requires advanced mathematical and computational techniques, making it difficult to test experimentally. Additionally, there are currently no direct observations or experiments that can definitively prove or disprove the concept, making it a subject of ongoing research and debate among scientists.

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