SCIENTIFIC VIEW
V I S I B L E M AT T E R
5%
D A R K M AT T E R
23%
DARK ENERGY
72%
What is dark matter? Apart from knowing that is five times more ordinary matter than dark matter (27% of dark matter vs. 5% ordinary matter), and that is present all-around the universe; dark matter does not interact with the electromagnetic force. What does this exactly mean? Dark matter does not absorb, reflect or emit light, which makes it remarkably difficult to find. Researchers have inferred dark matter existence from the gravitational effect that seems to act on the visible ordinary matter.
Figure 4 Illustration by Sandbox Studio, Chicago with Ana Kovaw.
P
Y
H
OMOLOG IST Y P E O L C SMO CA LO I YS G PLANET NINE
DARK M AT T E R
DARK FLUID
QUANTUM PHYSICS
BLACK HOLE
DARK ENERGY A N T I M AT T E R
DARK FLOW
Figure 5 Dark matter domain map.
Approaching Dark Matter from an astronomical sense introduces the explanation of how objects in the celestial space should move following specific rules based on observation1 . Most of the information that we get from the universe is provided by light emitted, absorbed or reflected by its objects. Data sent back from space proves the extension of the solar system. “Since scales of space and time are huge and conditions far too extreme to reproduce in a lab, scientists rely on mathematical modeling and computer simulations to understand our observations.� 2 This means that most of what we know right now relies on a hypothesis based on calculations to demonstrate what astrophysicists observe.
My interest in representing instances of the large, the small, and the unseen brings me to another unknown realm, one best served by epistemological questions. Epistemology, which Keith DeRose3 defines as questions about the nature, scope, and source of knowledge itself, is essential to get to answers within this unknown realm. Additionally, it’s important to understand Edmund Gettier’s phrase4 “Is Justified True Belief Knowledge?” Why is it important to understand the relationship between how we know and what we believe as true? Because at a large scale, the universe is a complete mystery in which our knowledge relates to what we think as real, not to what we have proof of existence. There is a vast difference between knowing and having faith in a fact. Taking into account the complexity of knowing any scientific concept, one example - of twisted dark matter - stands out as an especially complicated concept given the little information we have available with which to comprehend and assess it accurately. For instance, dark matter has no visible instance, so how can we know what it is? The knowledge acquired around dark matter is related to what it does. As we cannot tell what exactly dark matter is, we need to know it from mathematics, astrophysics and other angles that help us to create our knowledge. However, the way that we know things can certainly change the way we represent those same things.
THE DARK MATTER PROBLEM: A HISTORICAL PERSPECTIVE book by Robert H. Sanders
There is a need to understand the dark matter problem from a historical perspective to know how important each small discovery is. Robert H. Sanders reviews a historical perspective in his book “The Dark matter problem” 5 . The first modern conception of dark matter takes place at the time of Copernicus through an idea of celestial spheres. After Galileo’s telescopic observations showing anomalies on his data, and Newton laws being defined, there was a culmination in a more substantial hypothesis of an unseen part of the galaxy thanks to the French mathematician Urbain Le Verrier, who pointed out an undiscovered planet beyond Uranus. The relevance of Le Verrier’s theory was not apparent until the detection of Neptune in modern times. Otherwise, it would have meant a breakdown of Newtonian gravitational laws in the solar system because it would have denoted that everything believed at that point was a mistake. However, it wasn’t until the 1930s, when Frist Zwicky’s proposal of dark matter introduced the idea of a giant filling of a dominant component of the universe, after observing the rotations of the galaxies that form the Coma cluster. Based on Zwicky’s estimation of the mass of the galaxies calculated on the light they emitted, at the speed at which the galaxies were moving, they should have flown apart. Some mysterious and unseen dark matter seem to be adding mass to the galaxies to keep them together. Nevertheless, it took 40 years to accept Zwicky’s theory, which was the reconciliation of astronomical observations and the dynamics based on Newton laws.
Figure 6 Illustration by Sandbox Studio, Chicago with Ana Kovaw.
In the 1970s, Vera Rubin was studying Andromeda galaxy neighbor stars’ velocities, and she anticipated that the edge stars were moving more slowly than those at its axis because of the gravitational pull. Surprisingly, Rubin found that the stars moved as quickly as the ones in the middle. The only explanation is the presence of a more massive halo made of something that we can’t see surrounding the visible stars changing their velocity. Since then, other astronomical observations have confirmed anomalies in the way galaxies and light moves across space. If it happens that dark matter exists, its effects have been perceived and seen already, even though there is no visible instance of dark matter itself. In 1998, scientists on the DAMA experiment (a dark matter detector in Italy) discovered an unexpected pattern in their data. Although there is not proof it is dark matter, it could reveal that earth was moving through a dark matter halo explaining some of the anomalies cited above.
“If dark matter turns out to be something garden-variety, then maybe it will only take one experiment for people to be excited about it—and two for people to be borderline convinced,” Neal Weiner, director of the Center for Cosmology and Particle Physics at New York University stated. “But if something unexpected shows up, it might take more than that to persuade people 6 ”. There is still a long way to go to understand the remaining pieces that form the puzzle of the universe. In a ten years’ time span, there is hope on being able to have more accountable data to prove the existence of dark matter finally. Meanwhile, popular science has an essential role in the education of future generations of scientists that one day may determine the nature of dark matter. Eminences like Neil deGrasse Tyson and Stephen Hawking make physics more accessible to non-experts creating educational, exciting and engaging content.
Neil deGrasse Tyson Neil deGrasse Tyson is both an astrophysicist and a public figure who is creating experiences to learn science. Tyson’s approach to science has brought a lot of light to thousands of families wanting to discover the unrevealed mysteries of the Universe. Tyson has been part of the American Museum of Natural (AMNH) History since 1997 when he founded the Museum’s Department of Astrophysics. As the director of the Hayden Planetarium, Tyson has been involved in several projects wanting to explain the complexity of the universe in the realm of popular science. To fulfill this purpose, AMNH is screening Dark Universe presently.
“Dark Universe celebrates the pivotal discoveries that have led us to greater knowledge of the structure and history of the universe and our place in it—and to new frontiers for exploration7.” Tyson reaffirms how little we know about our galaxy. “Just within the last hundred years, we humans, inhabitants of a small planet orbiting this unexceptional star, have learned where the galaxies are, what they are made of, and how they got to be that way.We began to glimpse how we still don’t know about the universe.” Tyson’s commitment to popularizing science allows millions of ANMH’s visitors to have a better vision of the complexity of the Universe.
Stephen Hawking Both Tyson and Hawking have contributed enormously to society sharing their understanding of the complexity of the cosmos from different angles. Understanding the current status of dark matter research from the lenses of a rock star of Physics such as Stephen Hawking gives more than just hope.
“It has been a glorious time to be alive and doing research in theoretical physics. The fact that we human beings, who are ourselves mere collections of fundamental particles of nature, have been able to come this close to an understanding of the laws governing us and our universe is a great triumph8” Hawking stated that the next breakthrough in cosmology could involve dark matter because he considered that there is a link missing in cosmology and it consists in discovering the nature of dark matter and dark energy. Again, dark matter remains invisible and imperceptible, its existence is inferred through calculations and observation of galaxies. Sadly, Hawking’s contributions won’t be able to answer some of those questions anymore. However, his legacy will help other physicists to maybe have the only answer at some point.
REAL STATUS CERN Meanwhile, CERN, the European Organization for Nuclear Research hosts physicists and engineers from all over the world to prove the fundamental structure of the universe. Its facilities feature custom-made particle detectors that produce millions of collisions of particles to study and answer most of the unanswered questions about our cosmos. Regarding dark matter, CERN has the Alpha Magnetic Spectrometer (AMS) looking for dark matter, antimatter and missing matter from a module on the international space. AMS is a particle physics detector that provides data about dark matter presence and at the same time performs precision measurements of cosmic rays 9. Since 1949, when CERN was created, a lot of scientific advances have been achieved. CERN keeps looking for answers, who knows which one will be the next one answered.
Figure 7 The Alpha Magnetic Spectrometer looks for dark matter.
VOLUME 2/9