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How Do We Know The Universe Is ACCELERATING?

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Aatish Bhatia helped write this video! A big thanks for his help! Here’s his blog: http://www.empiricalzeal.com

The universe is expanding – this we know from looking at red shifts of distant galaxies – but the acceleration of the universe’s expansion is harder to measure. It requires measuring the change of recession velocity over time, and it’s done by comparing Type Ia supernovas as standard candles at different distances, which is how we know the universe is accelerating!

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REFERENCES

Type Ia supernovae
http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/snovcn.html
https://en.wikipedia.org/wiki/Type_Ia_supernova

Luminosity Distance
https://en.wikipedia.org/wiki/Luminosity_distance

Hubble diagram for type Ia supernovas (relatively close to earth): http://www.pnas.org/content/101/1/8/F3.expansion
http://www.astronomy.ohio-state.edu/~thompson/1101/lecture_fate_of_universe.html

Straightforward references:
Ryan Foley talking about WFIRST & Dark Energy
https://youtu.be/BhOAwXYKdmw?t=23m
Dark Energy FAQ:
http://www.preposterousuniverse.com/blog/2011/10/04/dark-energy-faq/
Why does dark energy make the universe accelerate?
http://www.preposterousuniverse.com/blog/2013/11/16/why-does-dark-energy-make-the-universe-accelerate/
David Spergel on dark matter & WFIRST
https://tvr2c.com/2016/06/01/53116-show-feat-professor-david-spergel-on-his-research-spanning-astrophysical-scales/

Slightly-technical references:
Permlutter article (old article but quite well explained & goes into future directions near the end)
http://supernova.lbl.gov/PDFs/PhysicsTodayArticle.pdf

Technical references:
Mukhanov’s Physical Cosmology
http://www.astro.caltech.edu/~george/ay21/readings/Mukhanov_PhysFoundCosm.pdf
Nobel Prize Summary
http://www.nobelprize.org/nobel_prizes/physics/laureates/2011/advanced-physicsprize2011.pdf
Cosmological redshift
https://en.wikipedia.org/wiki/Redshift#Expansion_of_space

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Created by Henry Reich

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