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Peter4075's user avatar
Peter4075's user avatar
Peter4075
  • Member for 12 years, 10 months
  • Last seen more than a week ago
  • United Kingdom
41 votes
3 answers
12k views

Sun's power density compared to a compost heap

40 votes
3 answers
41k views

Don't understand the integral over the square of the Dirac delta function

33 votes
10 answers
10k views

Why do objects follow geodesics in spacetime?

10 votes
2 answers
17k views

Hubble time, the age of the Universe and expansion rate

9 votes
3 answers
503 views

Why doesn't dark energy vary with time?

8 votes
2 answers
2k views

Nature of spacetime 4-vector and tangent space?

8 votes
3 answers
3k views

Finding the correct units for the energy-momentum tensor?

7 votes
1 answer
2k views

Geodesic deviation equation - why does the ordinary second derivative give the correct answer?

7 votes
1 answer
788 views

Trying to understand the weak gravitational field metric (1)

7 votes
1 answer
2k views

Why two different Lagrangians to derive geodesic equations?

6 votes
1 answer
963 views

How to tell if a star is in a galaxy?

6 votes
3 answers
667 views

How did Jocelyn Bell aim her radio telescope (phased array)?

6 votes
2 answers
570 views

Schwarzschild metric

6 votes
2 answers
448 views

Small change in theta - polar coordinates

6 votes
1 answer
7k views

Trying to understand Laplace's equation

5 votes
1 answer
487 views

Very basic question about empty universe

5 votes
1 answer
743 views

What does scalar phi represent in spacetime?

5 votes
4 answers
4k views

Einstein's "happiest thought"

5 votes
2 answers
3k views

Zero divergence of energy-momentum tensor and gravitational energy

5 votes
2 answers
2k views

Is speed of gravitational waves constant? [duplicate]

5 votes
1 answer
287 views

Naked eye cosmology?

4 votes
1 answer
149 views

Observable universe radius for distant observers

4 votes
2 answers
782 views

How does the critical density decide the fate of the Universe?

4 votes
1 answer
3k views

Difference between coordinate and proper distance in Schwarzschild geometry

3 votes
1 answer
323 views

Laws of physics and general relativity

3 votes
3 answers
7k views

Still trying to understand gravitational potential and Poisson's equation?

3 votes
4 answers
2k views

Two masses in deep space - collide or orbit?

3 votes
3 answers
3k views

Defining a Riemannian manifold - made easy?

3 votes
1 answer
1k views

Index raising and lowering - how does it work?

3 votes
1 answer
136 views

Is this covariant derivative identity true?