The Cosmic Cocktail: Three Parts Dark Matter | ॐ Homepage of Dr. Christopher B. Germann (Ph.D., M.Sc., B.Sc. / Marie Curie Alumnus)

The Cosmic Cocktail:

Three Parts Dark Matter

by Katherine Freese

Princeton University Press, Princeton,

New Jersey, 2014

264 pp., illus. 15 col., 73 b/w. Trade, $29.95

ISBN: 978-0-691-15335-3.

Reviewed by Christopher B. Germann

Marie Curie Fellow 'CogNovo'

Plymouth University, Cognition Institute

mail@christopher-germann.de

Published by Leonardo reviews (2015):

URL: https://www.leonardo.info/reviews_ar-

chive/mar2015/freese-germann.php

In nine compact chapters, Katherine Freese addresses the perhaps most fundamen-

tal question humankind can ask: What is the Universe made of? This question takes

the reader deep into the peculiar abysses of astroparticle physics. In order to intro-

duce the topic, she reminds us that, according to current theorizing, ordinary atomic

matter constitutes only ≈ 5% of the observable Universe. The remaining 95% consist

of dark matter (≈ 26%) and dark energy (≈ 69%), which are hitherto completely mys-

terious to scientists. These values are in themselves astonishing because they indi-

cate numerically how limited our epistemic understanding regarding the fundamen-

tal ontology of the Universe really is. The physical presence of dark matter is cur-

rently purely hypothetical. Its existence is logically inferred from its attractive grav-

itational effects on ordinary matter (i.e., gravitational lensing). By contrast, as

Freese points out, dark energy is an unidentified repulsive anti-gravitational form

of energy that is assumed to accelerate the expansion of the Universe. Evidence for

its effects is primarily based on spectroscopic measurements of distant supernovae

and their associated photometric redshifts.

According to Freese, the field of astroparticle physics is still in its infancy stage, and

there exists a wide future scope for potentially paradigm changing discoveries

whose significance might be comparable to the second Copernican revolution or the

shift from the geocentric to the heliocentric worldview. She is optimistic that sci-

ence will be able to solve the riddle of dark matter in the foreseeable future. How-

ever, dark energy, which is stipulated to be ubiquitous, is a different animal. Freese

emphasises that science is not even close to answering any questions concerning

its nature. Dark matter is at least theoretically detectable, and it can, therefore, be

investigated experimentally by probing for a new type of subatomic particle. How-

ever, researchers are groping in utter darkness when it comes to dark energy.

Nev-

ertheless, our scientific perspective on reality is literally expanding. According to

Freese, the angular resolution of telescopes is increasing faster than Moore's law

would prognosticate, namely by about a factor of 10 every two or three years. Fol-

lowing the author's line of thought, it is interesting to note that researchers in re-

lated domains observe similar exponential trajectories whose combinatorial syner-

gies are difficult to predict

a priori

, for instance, computational algorithms for image

analysis are steadily evolving unprecedented levels of sophistication and high-per-

formance computing enables ever more powerful analyses and simulations of in-

creasingly big-data scenarios.

The book puts the main focus of attention on the quest for dark matter detection

that is one of the hottest topics in contemporary science. This shadowy component

cannot be directly detected with current methods, primarily because it does not in-

teract with light, hence the eponymous nomenclature. Freese describes the various

experimental approaches physicists employ to search for it in a concise and acces-

sible way. Furthermore, she describes her career as a woman in this predominantly

patriarchal disciplinary territory and how she deals effectively with MACHOs (Mas-

sive Astrophysical Compact Halo Object) and WIMPs (Weakly Interacting Massive

Particles). In this context, she finally presents her own co-invention: a DNA-based

method for the detection of dark matter [1]. This truly interdisciplinary hybrid-ap-

proach to dark matter detection has the potential to enable nanometre resolution

for tracking of WIMPs. If it works (which has yet to be demonstrated), this extremely

sensitive detector would outperform all of the existing technologies available to-

day, and Freese and et al would take a leading position in the highly competitive

field. The following quote from the book exemplifies her enthusiasm: "

Now we have

come full circle. It is an intriguing prospect that we can use the DNA created from

stardust to search for astrophysical dark matter particles

" (p.179). At present, the

physics community attempts to cross-validate experimental results by methodo-

logical triangulation: 1) by the creation of dark matter particles in the particle accel-

erator complex at CERN, 2) by direct detection in sub-terrestrial laboratories, and 3)

by indirect detection via products resulting from particle (WIMP) annihilations. The

stated objective is to obtain convergent evidence from independent sources in order

to shed light on the long-standing dark matter conundrum.

In addition to presenting the 21

century view of the Universe, the book chronicles

the history of the exploration of dark matter. Freese expounds why Edwin Hubble's

discovery of the expansion of the Universe [3] was crucial for the development of

the discipline. Extending his line of research, the 2011 Noble Price in physics was

awarded "

for the discovery of the accelerating expansion of the Universe through

observations of distant supernovae

" [4]. In other terms, the Universe is expanding

at an exponentially increasing velocity. Fascinatingly, although Freese is not very

explicit on this point, current mathematical models postulate that its acceleration

is not limited to the speed of light because this speed limit only applies to objects

within space-time. By contrast, the metric expansion of space-time itself is not

bound to this maximum. This is a very astonishing extrapolation, to say the least.

Another topic Freese discusses is the genesis of the Universe (Big Bang theory).

However, she does not address the inherent deep philosophical questions concern-

ing universal causation (e.g., the Aristotelian "unmoved mover" and the associated

problem of infinite causal regress). Instead, she puts focus on reductionist experi-

mental research programs. For example, she delineates the workings of the Large

Hadron Collider at Europe's CERN research centre, the most powerful particle accel-

erator in the world, and she reviews the recent ground-breaking experimental dis-

covery of the Higgs Boson (a new elementary particle), which had been theoretically

predicted since 1964 [2]. This empirical triumph of atomism was rewarded with the

2013 Nobel Prize in physics [5]. Freese points out that the questions concerning the

nature of the macro-scale of the Universe and the micro-scale of atoms are tightly

interwoven.

To conclude, the cosmic cocktail has profound effects on the reader because it

raises awareness to the fact that physics is currently unable to account for the big-

ger proportion of the constituents of the Universe. Its well-balanced ingredients

contain a mixture of cutting-edge science enriched with a measure of history of cos-

mology and infused with oftentimes sparklingly amusing autobiographical details.

This unique blend is rounded off with several intriguing pictorial bindings. Straight

up! Taken together, the cosmic cocktail provides a rich taster of some of the core

areas of modern astronomy and particle physics, and it is a comprehensive primer

for the general educated layperson who is interested in the recipe of the cosmos. It

leaves the reader wondering what the future of physics has in store. Until then, the

dark side of the Universe remains an enigma to all great minds on spaceship earth.

References

[1] Drukier, A., Freese, K., Lopez, A., Spergel, D., Cantor, C., Church, G., Sano, T. (2015). "New Dark Matter Detectors us-

ing DNA or RNA for Nanometer Tracking".

Instrumentation and Methods for Astrophysics

http://arxiv.org/pdf/1206.6809v2.pdf

[2] Higgs, P. (1964). "Broken Symmetries and the Masses of Gauge Bosons".

Physical Review Letters

(

), 508-509.

https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.13.508

[3] Hubble, E (1929). "A relation between distance and radial velocity among extra-galactic nebulae".

PNAS

(

), 168-

173. http://www.pnas.org/content/15/3/168.full.pdf

[4] "The Nobel Prize in Physics 2011". Nobelprize.org. Nobel Media AB 2014. 10 Feb 2015. http://www.nobelprize.org/no-

bel_prizes/physics/laureates/2011/

[5] "The Nobel Prize in Physics 2013". Nobelprize.org. Nobel Media AB 2014.10 Feb 2015. http://www.nobelprize.org/no-

bel_prizes/physics/laureates/2013/