Your Daily Equation #15: The Planck Length - Why String Theory is Hard to Test | Summary and Q&A

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April 20, 2020
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World Science Festival
Your Daily Equation #15: The Planck Length - Why String Theory is Hard to Test

TL;DR

The Planck length, mass, and time are fundamental quantities that emerge from the fundamental constants of nature and have implications for theories like string theory.

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Q: What is the significance of the Planck length, mass, and time?

The Planck length represents the smallest possible length scale in the universe, while the Planck mass represents an extremely large mass scale. The Planck time represents the smallest possible time scale. They provide insights into the fundamental structure of spacetime and energy.

Q: How are the Planck units derived?

The Planck units are derived by combining the fundamental constants of nature, such as the speed of light, Planck's constant, and Newton's constant of gravitation, with specific exponents to obtain units of length, mass, and time.

Q: What are the numerical values of the Planck length, mass, and time?

The Planck length is approximately 10^-33 centimeters, the Planck mass is about 10^19 times the mass of a proton, and the Planck time is about 10^-43 to 10^-44 seconds.

Q: How do the Planck units relate to theories like string theory?

The Planck units provide a natural scale for theories that combine gravity, quantum mechanics, and other fundamental forces, such as string theory. The numerical values of the Planck units determine the typical scales at which these theories can be tested.

Summary & Key Takeaways

• The Planck length, mass, and time are quantities that arise from the fundamental constants of nature.

• The Planck length is about 10^-33 centimeters, representing the smallest possible length scale.

• The Planck mass is about 10^19 times the mass of a proton, representing an extremely large mass scale.

• The Planck time is about 10^-43 to 10^-44 seconds, representing the smallest possible time scale.