How do we at the early universe?

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How

do

we

“look”

at

the

early

universe?

Posted

on

December

6,

2012

by

Jake

Wisser

One of

the main goals of science today is to explain how the universe came to be
what it is today, in particular, what did the universe look like at the beginning of
the time? But how can we know what the universe looked like after the Big Bang
without reversing

time? The answer is that we look really, really, really, far out. If
we look far out enough, on the scale of billions of light years, then the light from
that galaxy took billions of years to reach us, so we are effectively looking back in
time. Quasars,
extremely bright galaxies with giant black holes eating up matter
at the center, are the furthest out objects that we are able to see. For instance, a
quasar was recently discovered 13 billion light years away from earth. The
universe is only 13.7 billion
years old, so we are looking at light that took 13
billion years to get to us. We are seeing what the quasar looked like when the
universe was only 772 million years old! That sounds like a very long time, but on
the cosmological scale, it is a relatively
short amount of time. So what did the
early universe “look like?” Well, it was mostly hydrogen and helium. The heavier
elements (metals and such) were formed by the death of stars, and there weren’t
that many (in the cosmological sense) stars at the beginn
ing of the universe. Also
confirming this is the fact that the gas around the quasar was not ionized;
meaning the hydrogen atoms still had their electrons. The only thing able to
ionize a gas is starlight.

I think that it is very interesting how we can jus
t look really far away to see what
the early universe looks like. Since the speed of light is only so fast, it limits what
we can see, or even know. If the sun were to disappear right now, we would have
no idea for eight minutes. We wouldn’t even feel the
gravitational effect for eight
minutes because gravity also travels at the speed of light. As telescopes become
increasingly advanced, we can get closer and closer to finding out what the
universe looked like at the time of the Big Bang.

Here’s a link abou
t the quasar if you want to learn a little more:

www.space.com/18773
-
distant
-
black
-
hole
-
quasar
-
early
-
universe.html/



Superconductors

Posted

on

November

28,

2012

by

Jake

Wisser

This one again comes c
ourtesy of StumbleUpon and is one of the cooler things
that I have ever come across on the Internet. Here’s the video:

That thing that is just floating in midair over the magnet is called a
superconductor. A regular conductor (like a copper wire) is an exc
eptionally good
carrier of electrical current (in contrast to insulators, like rubber, which carry no
current). Normal conductors have low

resistance

to the flow of electricity,
insulators have high

resistance. Superconductors have no resistance.
Supercond
uctors can be made of many different materials, but the catch is that
most materials do not become superconductors until they are cooled to extremely
low temperatures. In fact, one of the goals of modern science is to find materials
that become superconduc
ting at room temperature (imagine being able send a
current from one place to another with no energy lost, today power cables lose
enormous amounts of energy due to resistance). That’s the first property of
superconductors: zero resistance to electric curr
ent. The second property is
known as the Meissner effect, which is the tendency of superconductors to try to
cancel out any external magnetic field applied to them. They do this by
generating currents, which create magnetic fields of their own that cancel
out the
applied field. But that’s not so important. What is important is that some of the
applied field penetrates the superconductor shell. Another thing about
superconductors is that they want to keep this field the same. They don’t like
change. So, in t
he process of trying to lock this field in place, they lock themselves
in place. They need to keep the field the same throughout. So that’s where this
cool levitation effect comes from. It’s definitely one of the cooler effects of
superconductivity (even i
f it isn’t the most practical effect). Here’s a TED Talk
about the same phenomenon if you want to learn a little more about the details
from someone who is a little more qualified to give them.

http://www.ted.com/talks/boaz_almog_levitates_a_superconductor.html



Invisibility

Posted

on

November

14,

2012

by

Jake

Wisser

This next one comes courtesy of StumbleUpon. Whilst doing a little bit of
procrastinating, I came across this article about invisibility. It turns out that
Harry Potter’s invisibility cloak is not that far from reality. There are actually
several types of
invisibility cloaks in the making today, so hopefully they will
become practical within our lifetimes (for better or worse).

The first type makes use of the mirage effect, the same one that causes you to see
“puddles” on the road on a very hot day. The tem
perature difference between the
asphalt and the air bends the light toward your eyes, instead of allowing it to
bounce off the pavement. So, you see the sky instead of the road. Carbon
nanotubes are extremely good conductors of heat, so when they are heate
d up,
the light will bend around them, and effectively cloak them. Unfortunately, sheets
of carbon nanotubes are extremely small, and in order to be cloaked need to be in
a petri dish full of water. No so practical.

Another type of invisibility involves using materials that are smaller than the
wavelength of a certain type of light (called metamaterials). Since these materials
are so small, they can actually bend the light around an object, causing it to be
invisible
(since we see the light reflected off of an object). There are a few
problems with this method. It is very small (on the scale of micrometers), and it
only works in two dimensions. Again, not ideal.

The last type of invisibility is a little bit more compli
cated, but more feasible. It
involves retroreflective material (the same stuff on bike reflectors and street
signs) that reflects light in exactly the same direction from which it came.
Essentially, the idea is that a camera behind the thing you are trying

to make
invisible records the background, sends it to a computer, which then projects the
background onto the thing that you are trying to make invisible. Because of the
retroreflective material, the image looks like it is

assimilated

with the rest of the

landscape. Its a little more complicated than that, but that’s the central idea. This
actually has some applications (like getting rid of blind spots in cars), but it’s still
not the cloaking devices you see in science fiction. You don’t see Harry Potter
carrying around video

equipment

and computers.

Unfortunately,

it looks like
we’ll have to wait a little longer for a convenient way to disappear.

Lasers

Posted

on

November

7,

2012

by

Jake

Wisser

I recently read an article for

another class about “antilasers,” and as a result, I
had to do a little research about how exactly a laser works. So I figured I’d post
about that this week, because everyone loves lasers right?

Ok, so it turns out that LASER is actually an acronym for Li
ght Amplification by
Stimulation Emission of Radiation. The basic principle at work is the principle of
stimulated emission, which was discovered by Albert Einstein, but more about
that later. What we consider a laser consists of two main parts: a “gain me
dium”
and an amplifier (which is nothing more than two parallel mirrors). The gain
medium is a material that is used to produce photons (little “packets” of light). In
order to create these packets of light, a current is run through the gain medium.
The at
oms that make up the gain medium get “excited” when the current is run
through them, and jump up an energy level. Sometimes, the atoms will get
excited enough that they will emit a photon, which we see as light of a particular
color. The atom then falls ba
ck down to its original energy level when it emits the
photon. Here’s where the principle of stimulated emission comes in. It states that
when an atom emits a photon traveling in a particular direction, it causes atoms
around it to also emit photons travel
ing in the same direction. Then there are the
two mirrors. Photons that hit the mirror perpendicular to the surface will be
reflected back and forth between the two mirrors, and will stay in the gain
medium longer than those that only hit the mirror once o
r twice. Since these
photons stay in the medium longer, they cause the emission of more photons
going in the same direction as they are. This causes the “build up” of photons
going in a certain direction, which corresponds to a certain frequency (color) an
d
spatial orientation of light beam. These photons are then released, and we see
them as a laser beam. Cool right?







Controversy

(sort

of)

Over

the

Higgs

Boson

Posted

on

September

21,

2012

by

Jake

Wisser

As I’m

sure you’ve heard, physicists at the Large Hadron Collider in Switzerland
have seen the infamous Higgs Boson. Although it may not qualify as media
-
coverage
-
worthy controversy, there is a stir within the science community about
who deserves the Nobel Prize

for predicting the existence of the Higgs Boson.

Before I get to that, however, I’ll give everyone a little background information on
the particle everyone is talking about, while sparing you the more esoteric details
(most of which I have trouble underst
anding anyway). So, in physics, there are
four fundamental forces: the strong force (which holds atomic nuclei together),
the electromagnetic force, the weak nuclear force (which deals with radioactive
decay), and gravity. The standard model of particle fo
rces only addresses the first
three, as it is particularly difficult to unite gravity with these other forces, but that
is a different story that involves string theory and quantum gravity. These forces
arise from mathematical symmetries in the equations o
f the standard model
(called local gauge symmetries). The problem with the standard model came
from the Z and W bosons (these particles are the carriers of the weak force).
These particles needed to be very massive, but if physicists just “gave” the
partic
les mass in the equations, the symmetry that predicted their existence
would be ruined. So basically what the Higgs field (boson) does is interact with
these particles to give them energy, and according to Einstein, mass. The Higgs
boson is essential to th
e standard model because it is the particle (field) that gives
the Z and W bosons mass.

The controversy is over who deserves the prize. Six physicists came up with the
idea for the Higgs field almost simultaneously and independently (Peter Higgs,
Tom Kibbl
e, Gerald Geralnik, Carl Hagen, Francois Englert, and Robert Brout).
The problem is that only three people can share a Nobel Prize. Higgs published
his paper first, but Geralnik, Hagen, and Kibble (who published last) gave a
“more complete” model in their
paper. Some also say that the six physicists’ work
didn’t advance enough past earlier work to merit a Nobel Prize, and others argue
that it was the work of later physicists that lead to the Higgs boson as we know it
today and that those physicists (Steven
Weinberg and Abdus Salam) who deserve
recognition. Personally, I think the prize should go to Geralnik, Hagen, and
Kibble. All six of the physicists came up with the idea at the same time, but
according to the article, these guys gave the most complete mod
el in their paper.
The only reason the name stuck with Higgs is due to a mis
-
citing of a paper in an
article written by Steven Weinberg, and that definitely shouldn’t come into play.
Even though they didn’t connect the Higgs field with the Z and W bosons (
that
was the work of Weinberg and Salam) they “gave them the tool they had to have,”
according to Gerald Geralnik. I think this was an interesting case of how credit
should be shared when many people come up with the same idea at the same
time. On a closin
g note, since the Higgs boson is such a popular topic in science
right now, it will likely be the subject of a few blogs to come.