Introduction to Cosmology

256 Epilogue

0 0.5 1 1.5 2

Redshift z

• 0.5

0

0.5

1

Δ

(m

• M

)

always accelerates

accelerates now

decelerates in the past

always decelerates

flat

open

closed

Figure 12.1Evidence for transition from deceleration in the past to acceleration today. The
differencem–Mis defined in Equation (2.60). The blue line shows a model that fits the data,
where acceleration happens at late epochs in the history of the universe (i.e. starting a few
billion years ago, and billions of years after the Big Bang). The plot uses binned data from the
Union2 compilation [2]. With permission from the author. (See plate section for color version.)

Occasionally we have had reason to discuss a universe with extra dimensions: the
cyclic universe in Section 7.4, some models of dark energy in Section 11.4. They
remain candidates.
The future will bring great improvements in observational capacity, as we have
witnessed ever since COBE, so cosmology will remain an active and fascinating field.
I thank the reader for her/his patience to come to this sentence!

References

[1] Huterer, D. 2011Adventures in Cosmology, ed. D. Goodstein, World Scientific Pub. Co., and
preprint arXiv:1010.1162 [astro-ph.CO].
[2] Amanullah, R.et al. 2010 Astrophys. J. 716 , 712.