# Einstein's Biggest Blunder, Explained | Summary and Q&A

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August 1, 2019
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minutephysics
Einstein's Biggest Blunder, Explained

## TL;DR

Albert Einstein's equation of general relativity relates mass, energy, and gravity, and has led to two different solutions for describing the universe.

## Key Insights

• ๐ฎ Albert Einstein's equation of general relativity revolutionized our understanding of gravity and replaced Newton's law of gravitation.
• ๐ The equation is a complex system of differential equations that relate mass, energy, and gravity to the curvature of spacetime.
• ๐ป Einstein's equation has two solutions: one with a constant density and one allowing for a changing universe.
• โ The observations of the accelerating expansion of the universe supported the inclusion of Einstein's constant in the equation.

## Transcript

In 1915, Albert Einstein published a very important equation - no, not that one - the one he published didnโt just relate mass and energy, but mass, energy and gravity - this equation replaced the older โNewtonโs law of Gravitation,โ which you may be familiar with, and it remains to this day our best description of how gravity works. Just like how ... Read More

### Q: How does Albert Einstein's equation of general relativity relate to Newton's law of gravitation?

Einstein's equation is a more comprehensive and accurate description of gravity. It relates mass, energy, and gravity by incorporating the curvature of spacetime, while Newton's law only describes the force of gravity between two objects.

### Q: What were the implications of Einstein's equation for the orbit of Mercury?

Einstein's equation correctly predicted an anomaly in the orbit of Mercury, which could not be explained by Newton's law. This provided experimental confirmation of the accuracy of his equation and its superiority over Newton's law.

### Q: What are the two solutions to Einstein's equation for describing the universe?

The first solution, taken by Einstein, involves adding a new term to the equation, allowing for a non-zero density and the presence of matter in the universe. The second solution, proposed by physicist Alexander Friedmann, assumes a changing universe and does not require the added term.

### Q: How did later observations impact Einstein's equation and the cosmological constant?

Measurements made in 1998 showed that the universe's rate of expansion is not slowing down but actually accelerating. This discovery highlighted the role of Einstein's constant in describing the universe and validated its inclusion in the equation.

## Summary & Key Takeaways

• Albert Einstein's equation of general relativity replaces Newton's law of gravitation and is our best description of how gravity works.

• The equation is a system of ten second-order partial differential equations that relate mass, energy, and the curvature of spacetime.

• Einstein found two solutions to the equation: one with a non-zero density term, allowing for a universe with "stuff," and one assuming a static universe.