![Page 1: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/1.jpg)
The Universe: where does it end?
Chris NorthCardiff University
![Page 2: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/2.jpg)
The speed of light
c = 299,792,458 m/sor 670,616,629 miles per houror 2 million million furlongs per fortnightor ~300,000 km/s
That’s fast, but how fast?
0.13 seconds 0.1 microseconds 1 nanosecond3 milliseconds
![Page 3: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/3.jpg)
Light travels…
…to the Moon in 1.3 seconds
Light travel time
…to the Sun in 8.3 minutes…across the Solar System in 8.3 hours
![Page 4: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/4.jpg)
Light travels…
Light travel time
…across the Solar System in 8.3 hours…to the nearest star in 4.24 years…to the centre of the Galaxy in 30,000 years…to the Andromeda Galaxy in 2.5 million years
![Page 5: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/5.jpg)
Light travel time
Light travels…
…to the Andromeda Galaxy in 2.5 million years…to the Fornax Cluster in 65 million years…to a nearby “quasar” in 2 billion years…to most distant galaxies in 13 billion years
![Page 6: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/6.jpg)
Expanding Universe
![Page 7: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/7.jpg)
Hubble’s LawFornax Cluster 3C 273 Distant Galaxy
65 million years 2 billion years 13.4 billion years1400 km/s 54,000 km/s 690,000 km/s
0.005 c 0.18 c 2.2 c1.004 x 1.158 x 12 x
![Page 8: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/8.jpg)
Hubble’s LawFornax Cluster 3C 273 Distant Galaxy
65 million years 2 billion years 13.4 billion years
1400 km/s 54,000 km/s 690,000 km/s0.005 c 0.18 c 2.2 c
1.004 x 1.158 x 12 x
![Page 9: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/9.jpg)
The Expanding Universe
![Page 10: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/10.jpg)
The Expanding Universe
![Page 11: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/11.jpg)
The Expanding Universe
![Page 12: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/12.jpg)
The Expanding Universe
![Page 13: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/13.jpg)
The Expanding Universe
![Page 14: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/14.jpg)
Steady State vs Big Bang
![Page 15: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/15.jpg)
The nail in the coffin
![Page 16: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/16.jpg)
The nail in the coffin
![Page 17: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/17.jpg)
The cosmic horizon
![Page 18: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/18.jpg)
Fate of the UniverseS
ize
Time
Critical Density: 6 hydrogen atoms per cubic metre
Low density
High density
Critical density
![Page 19: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/19.jpg)
Universal composition (1800)
Density: 0.025 hydrogen atoms per cubic metre(0.004 x critical density)
Stars
![Page 20: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/20.jpg)
Universal composition (1950)
Gas
Dust
NeutrinosStars
Density: 0.25 hydrogen atoms per cubic metre(0.04 x critical density)
![Page 21: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/21.jpg)
Universal composition (1960)Gas
DustNeutrinos
Stars
Dark Matter
Density: 1.33 Hydrogen atoms per cubic metre(0.2 x critical density)
![Page 22: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/22.jpg)
Cosmic Microwave Background
1965199220012013
![Page 23: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/23.jpg)
Universal composition (now)Dark
Matter
GasNeutrinos
StarsDark Energy
Density: 6 hydrogen atoms per cubic metre(1.00 x critical density)
![Page 24: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/24.jpg)
Geometry of Space
![Page 25: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/25.jpg)
The Geometry of Space
![Page 26: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/26.jpg)
The Horizon Problem
![Page 27: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/27.jpg)
The Horizon Problem
![Page 28: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/28.jpg)
Inflation: the solution
![Page 29: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/29.jpg)
Fate of the UniverseS
ize
Time
Low density
High density
Critical density
Observed
![Page 30: The Universe: where does it end?astrog80.astro.cf.ac.uk/Talks/ExpandingUniverse.pdfThe Universe: where does it end? Chris North Cardiff University The speed of light c = 299,792,458](https://reader030.vdocuments.us/reader030/viewer/2022041100/5ed80a35cba89e334c67216d/html5/thumbnails/30.jpg)
Remaining questions
What is dark
energy?
What is dark
matter?
What is inflation?
What caused the Big Bang?