Skills

Physics 12: Astrophysics and Cosmology

14 weeks · 2 milestones

The expanding universe, the Big Bang and how we measure it. An elective of the Varsity Curriculum: Physics. Free sources only.

Part of: Physics · Proves for: UG

Milestone map

2 milestones

The expanding universe

7 weeks (about 12 hrs/week)

Work through the 8.286 slides and readings on Hubble expansion, the Friedmann equations and the early universe. Then solve the 8.286 problem sets, then the quizzes timed. Self-check: MIT 8.286 quizzes with solutions.

Proof required

Link the public repo with the 8.286 problem sets, then the quizzes timed written up (a typeset PDF, LaTeX source or notebook), and show the self-check: which answers matched and how you fixed the ones that did not.

What gets checked

Scale factor and redshift are related correctly.
Units are consistent across cosmological distances.
Quizzes are marked against their solutions.

Common mistakes

Answers copied from the key with no working.
Wrong units or missing signs.

Powstik Guide

A public write-up of the 8.286 problem sets, then the quizzes timed, with the self-check shown.

Steps

Study the linked course and chapters.
Solve the problems on your own first.
Check them against the self-check and rework the misses.
Typeset the write-up (LaTeX or a notebook) in a public repo.
Ask someone who knows physics to check it.

Template

README
Physics 12: Astrophysics and Cosmology, unit 1: The expanding universe
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

No working shown.
The self-check result is missing.

Resources

Foundationstart here

Depthgo deeper

What a verifier looks for

Scale factor and redshift are related correctly.
Units are consistent across cosmological distances.
Quizzes are marked against their solutions.
Is the physics right, not just the final number?

You'll sign in first, then come straight back here.

Measure the accelerating expansion from supernovae

7 weeks (about 12 hrs/week)

Make an analysis of the Union2.1 type Ia supernova data that fits flat universe models and estimates the matter density Ωm. Fit distance modulus against redshift for flat models with matter and dark energy, using the published errors, and look at the residuals.

Proof required

Link the public repo with the analysis notebook and the data's source, the result with its uncertainty, and a README that says what you did and what limits the result.

What gets checked

The fit gives Ωm with an uncertainty from the published errors.
A model with no dark energy is fitted too, and the two are compared.
The result is compared with published values (about 0.3).

Common mistakes

A result with no uncertainty.
Code or data that cannot be rerun from the repo.

Powstik Guide

An analysis of the Union2.1 type Ia supernova data that fits flat universe models and estimates the matter density Ωm, in a public repo.

Steps

Write down what you expect before you start.
Fit distance modulus against redshift for flat models with matter and dark energy, using the published errors, and look at the residuals.
Work out the uncertainty from your own data.
Compare with the accepted value and explain any gap.
Write the README and ask someone who knows physics to check it.

Template

README
Physics 12: Astrophysics and Cosmology — Measure the accelerating expansion from supernovae
What I expected:
Method:
Result (value ± uncertainty):
Accepted value and comparison:
What limits the result:

What gets sent back

No uncertainty, or one that is guessed.
Code that does not run.

Resources

Foundationstart here

What a verifier looks for

The fit gives Ωm with an uncertainty from the published errors.
A model with no dark energy is fitted too, and the two are compared.
The result is compared with published values (about 0.3).
The uncertainty is worked out from the data or runs (spread of repeats, instrument limits, fit errors or a range of inputs), not guessed, and it is shown on the result.
Is the physics right, and could someone rerun it from the repo?

You'll sign in first, then come straight back here.

Part of

Physics 12: Astrophysics and Cosmology →

Related outcomes

Milestone map

2 milestones

The expanding universe

7 weeks (about 12 hrs/week)

Proof required

What gets checked

Scale factor and redshift are related correctly.
Units are consistent across cosmological distances.
Quizzes are marked against their solutions.

Common mistakes

Answers copied from the key with no working.
Wrong units or missing signs.

Powstik Guide

A public write-up of the 8.286 problem sets, then the quizzes timed, with the self-check shown.

Steps

Study the linked course and chapters.
Solve the problems on your own first.
Check them against the self-check and rework the misses.
Typeset the write-up (LaTeX or a notebook) in a public repo.
Ask someone who knows physics to check it.

Template

README
Physics 12: Astrophysics and Cosmology, unit 1: The expanding universe
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

No working shown.
The self-check result is missing.

Resources

Foundationstart here

Depthgo deeper

What a verifier looks for

Scale factor and redshift are related correctly.
Units are consistent across cosmological distances.
Quizzes are marked against their solutions.
Is the physics right, not just the final number?

You'll sign in first, then come straight back here.

Measure the accelerating expansion from supernovae

7 weeks (about 12 hrs/week)

Proof required

Link the public repo with the analysis notebook and the data's source, the result with its uncertainty, and a README that says what you did and what limits the result.

What gets checked

The fit gives Ωm with an uncertainty from the published errors.
A model with no dark energy is fitted too, and the two are compared.
The result is compared with published values (about 0.3).

Common mistakes

A result with no uncertainty.
Code or data that cannot be rerun from the repo.

Powstik Guide

An analysis of the Union2.1 type Ia supernova data that fits flat universe models and estimates the matter density Ωm, in a public repo.

Steps

Write down what you expect before you start.
Fit distance modulus against redshift for flat models with matter and dark energy, using the published errors, and look at the residuals.
Work out the uncertainty from your own data.
Compare with the accepted value and explain any gap.
Write the README and ask someone who knows physics to check it.

Template

README
Physics 12: Astrophysics and Cosmology — Measure the accelerating expansion from supernovae
What I expected:
Method:
Result (value ± uncertainty):
Accepted value and comparison:
What limits the result:

What gets sent back

No uncertainty, or one that is guessed.
Code that does not run.

Resources

Foundationstart here

What a verifier looks for

The fit gives Ωm with an uncertainty from the published errors.
A model with no dark energy is fitted too, and the two are compared.
The result is compared with published values (about 0.3).
The uncertainty is worked out from the data or runs (spread of repeats, instrument limits, fit errors or a range of inputs), not guessed, and it is shown on the result.
Is the physics right, and could someone rerun it from the repo?

You'll sign in first, then come straight back here.