[MUSIC PLAYING]
We are all born scientists.
Curiosity is a fundamental part of being human.
So why don't you use that brilliant brain of yours
for the betterment of science?
I'm talking about citizen science.
[MUSIC PLAYING]
The professional astronomer or astrophysicist
is a pretty recent phenomenon.
In the past, astronomy was often performed
by nobility and extremely enthusiastic amateurs.
Take William Herschel.
By trade, a classically trained musician,
but as an amateur astronomer, he discovered Uranus
and was the first to observe binary star
systems, among other things.
Although it seems like the scientific exploration
of our universe is now in the hands of full-time career
astroprofessionals, a ton of really valuable science
is still done by people with proper day jobs.
Today, I want to talk about some of the stunning contributions
still being made by citizen scientists
and the contributions you can make.
Some of the most important amateur astronomy work
is in spotting changes in the night sky,
spotting things like comets and supernovae
or monitoring variable stars.
These are well within the capabilities
of good amateur telescopes, yet require
a lot of eyes on the sky for a lot of hours.
And that's not a good use of our giant professional telescopes.
Comets, in particular, are often discovered
by amateur astronomers.
Two particularly famous recent comets,
comet Hale-Bopp and Shoemaker-Levy 9,
were co-discovered by amateur astronomers Thomas Bopp
and Carolyn Shoemaker.
Shoemaker, in particular, was incredibly active,
discovering or co-discovering 32 comets, 377 minor planets,
and over 800 asteroids.
Supernovae are also fair game for amateurs.
These exploding stars show up as transient point of light,
typically in very distant galaxies.
Now, there are a number of supernova-hunting amateurs,
but perhaps the most impressive is Tim Puckett's effort out
of his Puckett Observatory in Georgia.
His Supernova Search program has found well over 300 supernovae,
contributing to many scientific papers.
While individual work can advance science,
often the biggest advances come from the efforts of a group
of people working together.
The American Association of Variable Star Observers,
founded in 1911, has generated an archive
of variable star data taken primarily
from amateur telescopes.
This international database houses
over 20 million variable star brightness measurements
dating back over 100 years.
Getting started with this sort of citizen science
takes a bit of dedication and cash,
but you can get started with even a relatively affordable
telescope, especially for variable star monitoring.
Fair warning, though, if you want your own supernova hunting
program, you'd better be ready to spend some money.
Aperture fever is no joke.
If you're more the artistic type and you
want to use a science-grade instrument on a spaceship,
then probably JunoCam is for you.
JunoCam is a camera mounted to the Juno Jupiter Orbiter.
It was deployed primarily for citizen scientist use.
NASA provides the raw, visible, and infrared images
to the public via their website, and talented folk
turn those streams of ones and zeros
into beautiful images, which NASA publishes.
The results are spectacular.
Citizen science isn't just about getting more telescopes
on the sky or public outreach.
There are some things that lots of regular human eyes
and brains can do much better than a small number
of scientists operating even the best computers in the world.
A lot of it has to do with pattern recognition, which
humans are uncannily good at.
The Zooniverse Project leverages this very human superpower
in lots of its projects.
For example, spotting supernovae or looking
for gravitational wave signals in LIGO and finding
planets forming in the debris disks of new solar systems.
And of course, the Zooniverse's first and founding project,
GalaxyZoo.
This project used citizen scientists
to classify the morphological types
of nearly 1 million galaxies.
The newest Zooniverse project is called Backyard Worlds--
Planet 9.
Its goal is to search beyond Neptune
for the potential ninth planet, as well
as looking for brown dwarfs--
cool, faint, failed stars--
that live, well, right now in Backyard.
The project has located nearby brown dwarves,
but citizens are still searching for Planet Nine.
Maybe you'll be the one to spot it.
You can also contribute to science
without using any of your her and brain power.
Just donate your computers.
Using the Berkeley Open Infrastructure
for Network Computing, or BOINC, you
can link your computer to others around the world
to form one giant computer.
With over 300,000 participants and over 800,000 computers,
processing an average of nearly 20 petaflops,
it is Guinness World Record's world's largest computing grid.
This all started with the City at Home
program, which looks through radio data for signs of signals
from intelligent life.
But there's also Einstein at Home,
which searches for LIGO gravitational wave
data for signals produced by rotating neutron stars.
And Milky Way at Home, which generates 3D dynamical models
of streams of stars using data from the Sloan Digital Sky
Survey.
So if you can spare a few of them computer cycles,
why not do some science with them?
Now, I'm not saying you shouldn't go to university
and become a professional scientist,
but I'm saying you don't have to in order to do real science.
I've just given some examples, so please share in the comments
if you've been involved in any of these or other cool citizen
science projects.
Links to everything I mentioned are in the description.
OK, time for the answers to the recent zero-point challenge
question.
There were two, both quizzing you
on the zero-point energy of the quantum vacuum.
Here we go.
The first question was about practical uses
of the quantum vacuum.
Now, geckos cling to surfaces by using what is essentially
the Casimir effect between the tiny hairs, setae,
on their feet and the surface.
So the obvious question is, how many geckos
would you need to leash in order to drag you up a wall?
An average gecko might be able to effectively apply
200,000 of their millions of setae at any one time,
and each seta can support 200 micronewtons of force.
Multiply those together and you get
that a gecko can support something
like 40 newtons, or four kilograms, in Earth gravity.
So how much do you weigh?
I need 20 geckos.
Finding them shouldn't be so hard.
It's getting the harness on the little suckers
that's the real challenge.
And the extra credit question.
So a simplistic theoretical estimate of the vacuum energy
density comes from assuming that there
are no virtual photons above a certain cut of frequency.
If you choose that to be the frequency corresponding
to a photon with the Planck energy,
you get a vacuum energy density of a ridiculously high 10
to the power of 112 ergs per centimeter cubed.
In this theoretical estimate, vacuum energy density
is proportional to the fourth power of cutoff frequency.
So my question was what cutoff frequency
is needed for this theoretical estimate
to give you the energy density implied by dark energy?
OK, so the energy density implied by dark energy
is around 10 to the power of minus 8 ergs per centimeter
cubed, or one joule per cubic kilometer.
Which is a surprising 120 orders of magnitude
lower than the theoretical estimate I just mentioned.
The frequency of a photon with the Planck energy
is the Planck energy divided by the Planck constant,
or an insane 3 by 10 to the power of 42 hertz.
And if vacuum energy is proportional
to the fourth power of cutoff frequency,
then this equation gives the relationship we need.
There are a bunch of constants in the cutoff frequency vacuum
energy relation, but they cancel out.
So we don't even have to know them.
That ratio of vacuum energies is 10 to the power of 120.
So we get a cutoff frequency for dark energy of 3
by 10 to the power of 12 hertz.
That corresponds to a photon wavelength
of a tenth of a millimeter, which
is in the far infrared part of the spectrum.
So what does this tell us?
Well, it tells us that the simplistic approach
of choosing the right maximum virtual photon
frequency definitely can't give us the vacuum energy
that we see as dark energy.
Photons with wavelengths shorter than 0.1 millimeters
definitely exist, and we see particle interactions
that require the exchange of much shorter
wavelength virtual photons.
Also, the first successful Casimir experiment
saw the force emerge when the plates were
separated by around one micrometer, 100 times smaller
than our 0.1 millimeter cutoff.
That proves the existence of virtual photons
with wavelengths smaller than the plate separation.
Also, without a very short-range Casimir force,
geckos would fall off walls.
So we randomly selected six correct answers
as winners of the challenge.
If you see your name below, that includes you.
You win a T-shirt.
And lucky you, we now have two new T-shirts on offer.
There's the heat death of the universe is coming,
which is also available for anyone to purchase.
A link in the description.
And exclusively for challenge winners and Patreon supporters,
we have astrochicken von Neumann,
conqueror of the galaxy.
Plus, of course, the original Space Time T-shirts.
Winners should email pbsspacetime@gmail.com with
your mailing address and let us know which T-shirt you'd like,
your US T-shirt size--
small, medium, large, et cetera.
See you all next week for a fresh new episode
of Space Time.
[MUSIC PLAYING]