BC SRC Pro-D Session:

THE UNIVERSEwith Astronomer Rachel Wang

at the H.R. MacMillan Space Centre

ASTRONOMER• Content knowledge expert• Presenter/interpreter• Program development• Public astronomy contact (e.g. interviews, questions, etc.)

ABOUT MERESEARCH

• Hon. Thesis (B.Sc) at TRIUMF- Using ultracold neutrons to probe physics beyond the Standard Model

• Cerro Tololo Inter-American Observatory (CTIO), Chile

- Assessing micro-variability of blazar PKS 0521-365

• Chandra X-ray Observatory- Constraining mass accretion models on low-luminosity supermassive black holes (proposal)

UBC ALUMNI• Combined Honours in Physics & Astronomy (May 2019)• Lecture TA

But enough about me...QUESTIONS FROM YOU!

What is SPACE? Like, the dark stuff?• Atoms are mainly empty space• Empty space (vacuum) is not truly empty – it's filled with quark-gluon field fluctuations

• Vacuum = space devoid of matter• Vacuum fluctuations

• Temporary change in amount of energy in a point in space (Heisenberg uncertainty principle)

• Particle-antiparticle creation of pairs of virtual particles Hawking radiation

What existed before the UNIVERSE came to be?• The Big Bang (BB) is a moment in time, not a location in space• Cosmological inflation – energy trapped in 'inflaton field' caused rapid expansion of

space• Developed around 1980 to explain several puzzles with the standard model of

cosmology (BB)• Initial singularity = gravitational singularity predicted by general relativity to have

existed before the BB, and is thought to have contained all the mass and spacetime of the Universe

• BB created the spatial (d=3) and temporal dimensions (d=1) as we know it• 'Before' refers to a moment in time, but time did not exist before the BB event

Alternatives to the INITIAL SINGULARITY• Loop quantum gravity – describes a cyclical Universe in

which a Universe is created and destroyed through a series of Big Bounces, each with different physical constants• Quantum fluctuations cause the universe to expand

• M-theory – the universe is one of many in a multiverse, and has budded off from another universe as a result of quantum fluctuations• Unifies all consistent versions of superstring

theory• Opposes idea that our Universe is unique

Why does the MOON rise later (~1 HR) each night?• Observation: as the Moon orbits the Earth, its position in the sky

appears to change night after night. In fact, it will appear to rise later by nearly an hour each day.

• Assumptions: we are close to the equator – daily delay of moonrise can vary considerably with latitude.

• What happens 24h later (in picture 2)?• Rotation rate of Earth: • Moon travel in orbit:

• Time for Earth to rotate 12o is...

Mathematical Details: The Nitty Gritty SINGAPORE

SINGAPORE

MOON

MOON

What is the MOST INTERESTING FIND youhave discovered?• Astronomy research: confirmation of (micro-)variability timescale of BL Lacertae /

Blazar object PKS 0521-365• Corroborated complementary data in X-ray and γ-ray regimes• Variability is a useful tool to investigate emission processes

• Physics research: quality assessment of proton beamline 1U at TRIUMF for maximizing ultracold neutron (UCN) production yield• Provided parameters for alignment of electromagnetic steering components;

assisted UCN yield increase

What is the MOST INTERESTING FACT youhave discovered?• There are more stars in the universe than grains of sand on Earth.• White holes are a hypothetical region of spacetime and singularity

which cannot be entered from the outside; it is the reverse of a black hole (re: 2 sides of the same coin).

• Spacetime can be deformed faster than the speed of light. This is the basis of Alcubierre's warp drive.

• * Nuclear pasta is a theoretical type of degenerate matter that is thought to exist in the crusts of neutron stars. If it does in fact exist, it would be the strongest material in the universe.

I saw Halley's Comet through a telescope and thought it was a streetlight. How do you IDENTIFY OBJECTS for what they are, and not what your brain rationalizes it as being?

Some good questions to ask yourself are:1. Does it twinkle? Atmospheric turbulence causes light from distant objects to become

distorted. This is why stars twinkle.2. Does it move from night to night? Planets appear to move across the sky due to the

rotation of the Earth.3. Is it the right time/position for the object to be up? Always a good self-check.4. How bright is it? The brightest star in the night sky is Sirius A (Dog Star) which has an

apparent magnitude of mV = –1.46. A full moon has mV = -12.5.

Is TIME TRAVEL possible?• Forward time travel = not currently feasible

• Time dilation – a person at the bottom of a tall building will experience their clock moving slower than a clock at the top to an outside observer (e.g. GPS)

• Backward time travel = feasible in our current theoretical model, but no technology• Einstein-Rosen Bridges (wormholes) - put someone in it and

accelerate it to v➝c, then bring it back to your starting point• Kerr (rotating) black holes – bend spacetime to allow for time

travel

How concerned are you about the effect of STARLINK on astronomical observations?

How concerned are you about the effect of STARLINK on astronomical observations?• Musk's argument: The ocean is so big that a few bits of plastic

would never hurt anyone; a thousand bits would be lost in the infinity.• Current: 422 satellites• Total: 12 000 (possible extension to 42 000)

• Proposed solution: paint them black• Issues & concerns: IR astronomy severely impacted (black

absorbs a lot of heat), bright and highly visible, increases space debris, global competitors contributing (e.g. OneWeb, Iridium) Credit: @GOTOObservatory

How does radio telescope at DRAO help us understand DARK ENERGY?• Canadian Hydrogen Intensity Mapping Experiment (CHIME)• (Accelerated) Hubble expansion due to dark energy• Baryon acoustic oscillations (BAOs) -- frozen acoustic

patterns in large-scale distribution of neutral hydrogen (HI)• Density variations present at beginnings of universe• Produced sound waves in plasma• Waves frozen when baryons decoupled from radiation

and universe became transparent

Space Centre:COMMON QUESTIONS

Why is PLUTO no longera planet?!

It was once my favourite planet too... downgraded in August 2006

– 14 years ago, yikes!

The IAU definition of a planet:

Must be in orbit around the Sun.

ORBITHas sufficient mass to

assume hydrostatic equilibrium (a nearly round

shape).

ROUNDHas 'cleared the

neighbourhood' around its orbit.

CLEARED PATH

What are DARK MATTER and

DARK ENERGY?Are they really 'dark'? Have we detected it yet?

• Repulsive force• Affects speed at which universe

expands (responsible for accelerated expansion of the universe)

• Causes objects to move away from one another (push)

DARK ENERGY

• Interacts through attractive force of gravity

• Affects how clustered objects are (reason why galaxies and clusters can exist)

• Causes objects to want to move toward one another (pull)

DARK MATTER

27%27% 68%68%

Will the SUN ever stop shining?

What will happen to the Earth? Are we all doomed?

...YES!The Sun is currently approximately halfway through its lifetime. In about 5 billion years, when its hydrogen fuel runs out and it can no longer undergo nuclear fusion, the Sun will swell in size and become a red giant.

It will engulf the Earth (as well as Mercury and Venus), and swell to the orbit of Mars.

Is SPACEexpanding faster than LIGHT?

But that would mean space exceeds the cosmic speed limit of 299 792 458 m/s...

The RAISIN BREAD Model• If we measure how quickly the most distant galaxies appear to be

moving away from us, that recession velocity exceeds light speed.• Edwin Hubble, 1929 – found that almost all galaxies seem to be moving

away from us, and the most distant ones move the fastest.• Balloon analogy: the Universe can be pictured as a surface of a balloon

covered in dots (galaxies). As the balloon inflates, each dot moves away from every other dot.• The dots themselves are not moving, it's the space in between

them that gets larger.

Do ALIENS(intelligent extraterrestrial life)

exist?Where are Jocelyn Bell's LGM (little green men)?

The FERMI PARADOX & RARE EARTH Hypothesis• Fermi Paradox – the apparent contradiction between lack of evidence for

extraterrestrial civilizations and various high estimates for their probability of existence (e.g. Drake equation)• Optimistic• 1970s, '80s – Carl Sagan and Frank Drake argue that Earth is typical

• Rare Earth Hypothesis – argues that the origin of life and the evolution of biological complexity required an improbable combination of astrophysical/geological events and circumstances• Pessimistic• Earth (and its lifeforms) is/are unique

Frontiers of Astronomy & Astrophysics:RECENT DISCOVERIES

* Last updated: 04/22/2020

LIGO/Virgo first to directly detect

gravitational waves

Gravitational Wave Direct Detection

AN ASTROPHYSICAL & ASTRONOMICAL TIMELINEOF DISCOVERIES

Closest known exoplanet to solar

system discovered by ESO

First instance of a GW event observed to

have a simultaneous EM signal

EHT obtains first black hole image of

M87*

Proxima Centauri b

Multi-messenger Astronomy

1st Black Hole Image

2015 2016 2017 2019

CREDITS: This presentation template was created by Slidesgo, including icons by Flaticon, and infographics & images by Freepik. Please keep this slide for attribution.

THANKS!Do you have any questions?

astronomer@spacecentre.caRachel Wang

spacecentre.ca

Supplementary Q&A Slides

Answers to other potential questions about the cosmos...

What is the eventual fate of our Universe?

What is the geometry of spacetime?

The shape of the universe is the local (curvature) and global (topology) geometry of the universe.

We seem to live in a 'flat' / Euclidean (0 curvature) spacetime – with only a 0.4% margin of error (Planck, WMAP).

Is the universe infinite or finite?

COSMOLOGY Related Questions

By fast-forwarding time on the FRW model / metric of our universe, cosmologists predict our eventual fate is the ultimate heat death of the universe.

The universe will asymptotically approach absolute zero and the universe enters a state of maximum entropy.

Presently unanswered; it is either infinite or finite.

If the universe is infinite, then it has always been infinite. At the BB, it was infinitely dense and since then, it has been getting less dense as space expands.

What happens if I fall into a black hole?

What is Hawking radiation?

This is black hole evaporation.

Imagine a pair of virtual particles pop into existence at the event horizon of a black hole, one on each side. To an observer, it looks like the black hole is emitting a particle and thus losing mass.

How did they take a photo of a black hole?

BLACK HOLE Related Questions

A brave astronaut who passes within a black hole's event horizonexperiences spaghettification.

Gravity exerted would be much stronger at their feet than their head (if they went in feet first).

They used a technique called Very Long Baseline Interferometry(VLBI).

It works by using an array of synchronized smaller telescopes that act as one large virtual telescope.

What happens if I fall into a black hole?

BLACK HOLE Related Questions

What is a telescope's "lookback time"? What is redshift?

Electromagnetic radiation from an object undergoes an increase in wavelength.

There are 3 main causes of redshifts in astronomy:(i) Doppler effect(ii) Universal expansion(iii) Gravitational / relativistic effects

Is light a particle or a wave?

LIGHT Related Questions

Light travels at a fast, but finite speed. Thus, light that reaches us from a distant object was emitted long ago and is very old when it finally reaches Earth.

This is what makes the study of galaxy evolution possible.

Light sometimes acts like a wave, sometimes like a particle – this is the wave-particle duality of light.

Like a wave, a photon experiences diffraction, interference, refraction/reflection, dispersion, coherence, frequency-shifts, etc.

Like a particle, a photon contains fixed energy, momentum, spin, and position.