Posts tagged Universe
Posts tagged Universe
One day, people will look back and refer to this as a time in which we didn’t know of life elsewhere in the Universe. Perhaps one day, only when extraterrestrial life is as a common paradigm as the fact that Earth orbits the Sun, will our ignorance be truly be understood.
Our Story in 1 Minute
If the universe is expanding, does that mean that I am getting bigger?
No. The electromagnetic forces that are holding you together are stronger than the expansion of the universe. This means that while the universe is expanding, you are not. Furthermore, while the space between galaxies is expanding, the galaxies themselves are not getting bigger; likewise with clusters of galaxies like the Local Group and even superclusters. The Virgo Cluster, for example, is ~100 million light years across and is marginally gravitationally bound. The attractive forces within the supercluster is slowed down by the expansion of the universe by approximately 20%.
Why is everyone leaving us? Does this mean that we are in the center of the universe?
It looks like everything is moving away from us because the universe is expanding! A useful tool to always keep in mind is the Cosmological Principle. This is commonly stated as ‘Viewed on a sufficiently large scale, the properties of the Universe are the same for all observers.’ This useful tool can be applied to the expanding universe. Since all observers in the universe (meaning your position in the universe will not affect one’s observations) will see the same expansion, everyone will see galaxies moving away from them! Following this, it seems like everyone would believe that they are at the center of the universe, but this can’t be. Every point in space is moving away from every other point in space; there is no unique center to the universe.
Is space expanding, or just galaxies moving apart in space?
Spacetime is constantly being created as the universe expands. With this expansion, galaxies seem to be moving away from us, but astronomers have a technique to test if galaxies are really moving. For the moment, imagine a really large sphere centered on our galaxy perhaps containing a few hundred galaxies. The galaxies along the surface of the sphere have two types of motion: random motion due to their own movement and motion due to the expansion of the universe. When each galaxy along the surface of the sphere is analyzed, they all have almost the same motion: the motion shared among each of these galaxies is due to the expansion of the universe and the motion that diverges from the motion which is caused by the expansion is random motion. It has been found that a significant proportion of the motion is due to the expansion of the universe and very little motion is random when we take into consideration galaxies at large distances. Thus, we can conclude that the motion of galaxies is indeed due to the expansion: the space between galaxies is moving, the galaxies are not receding in a classical sense. Going back to our tool, the Cosmological Principle, if the galaxies were indeed moving away from us, turning back time, the galaxies would be approaching a specific place in space and time where the Big Bang happened. This would violate the notion of a homogeneous and isotropic universe which would lead to the Big Bang happening in a particular place (ie: a special place in the Universe.) Since this cannot be the case, we can easily conclude that galaxies must not be receding away from us but rather that they appear to be.
Can recession velocity be greater than the speed of light?
Astronomers commonly probe the depths of space that reveal redshifts larger than one (z>1) which suggests that these observed objects are receding at greater speeds than that of light. Since nothing can move faster than light, we immediately know that these galaxies are not receding away from us with speeds greater than the speed of light. But if they seem to be moving away from us faster than the speed of light, what does this mean? The space itself is expanding faster than the speed of light! Recall that redshift is just the stretching of photons during their journey to our detectors. While the photons were on their journeys through space, space itself expanded faster than light which stretched these photons significantly to make the galaxies appear to be receding faster than light. Remember, nothing can move faster than light: except the expansion of space itself.
Where in space did the Big Bang happen?
Everywhere! And nowhere! To say that the Big Bang happened in a particular place in the universe would again violate the Cosmological Principle and the notion that there is no special place in the universe. Furthermore, the Big Bang created space, so to ask the question of where it happened is meaningless because prior to the creation of the universe, there was no space! The Big Bang was the creation of space and time whose spatial location in the universe has no meaning.
Are there any other questions you would like to see answered?
The Universe is Weird: A Song
A quark can never exist by itself in isolation
Something very odd happens when you try to sepparate them
The energy it takes, to break up those two best friends
is just enough to create two more to join back up with them
A photon has no mass…and thus travels at light speed
If you’re able imagine going that fast, and if you try I think you might be
You’d be emitted and absorbed in the exact same instant
even if you traveled from a star 13 billion light years distant.
THE UNIVERSE IS WEIRD
I’m kinda freaking out
What is this all about
Infinite unbounded sets
and hadronizing gluon jets
We’ll never understand
All of what we have at hand
At least that’s what I fear
An electron has a strong charge, as strong as a proton
And a tiny mass but not nonexistant like the photon
You might want to take a seat now, cause this might hurt your mind
It has mass and charge, yes, but not, apparently, a size
There’s a lot of stuff all around you right now
Your chair your friend your planet and your sister’s neighbor’s cow
Mundane mass and energy is all we know and undestand
but it’s only 4% of what the universe has at hand
I was driving in a van with my brother and I said
John, hey, guess what, like, dude, NO EDGE!
Because the universe does not exist in any way we can conceive it
No center, no edge, no none of that, whether or not you can believe it
Once upon a time, in a gassy liquid stew
A molecule was like “hey, I turned me into you”
This may be the biggest mystery of all the ones in which we dwell
How the universe created a tool with which to know itself
Lawrence Krauss gives a talk on our current picture of the universe, how it will end, and how it could have come from nothing. Krauss is the author of many bestselling books on Physics and Cosmology, including “The Physics of Star Trek.”
Black holes powering distant quasars in the early Universe grazed on patches of gas or passing galaxies rather than glutting themselves in dramatic collisions according to new observations from NASA’s Spitzer and Hubble space telescopes.
A black hole doesn’t need much gas to satisfy its hunger and turn into a quasar, says study leader Kevin Schawinski of Yale “There’s more than enough gas within a few light-years from the center of our Milky Way to turn it into a quasar,” Schawinski explained. “It just doesn’t happen. But it could happen if one of those small clouds of gas ran into the black hole. Random motions and stirrings inside the galaxy would channel gas into the black hole. Ten billion years ago, those random motions were more common and there was more gas to go around. Small galaxies also were more abundant and were swallowed up by larger galaxies.”
Quasars are distant and brilliant galactic powerhouses. These far-off objects are powered by black holes that glut themselves on captured material; this in turn heats the matter to millions of degrees making it super luminous. The brightest quasars reside in galaxies pushed and pulled by mergers and interactions with other galaxies leaving a lot of material to be gobbled up by the super-massive black holes residing in the galactic cores.
Schawinski and his team studied 30 quasars with NASA’s orbiting telescopes Hubble and Spitzer. These quasars, glowing extremely bright in the infrared images (a telltale sign that resident black holes are actively scooping up gas and dust into their gravitational whirlpool) formed during a time of peak black-hole growth between eight and twelve billion years ago. They found 26 of the host galaxies, all about the size of our own Milky Way Galaxy, showed no signs of collisions, such as smashed arms, distorted shapes or long tidal tails. Only one galaxy in the study showed evidence of an interaction. This finding supports evidence that the creation of the most massive black holes in the early Universe was fueled not by dramatic bursts of major mergers but by smaller, long-term events.
“Quasars that are products of galaxy collisions are very bright,” Schawinski said. “The objects we looked at in this study are the more typical quasars. They’re a lot less luminous. The brilliant quasars born of galaxy mergers get all the attention because they are so bright and their host galaxies are so messed up. But the typical bread-and-butter quasars are actually where most of the black-hole growth is happening. They are the norm, and they don’t need the drama of a collision to shine.
“I think it’s a combination of processes, such as random stirring of gas, supernovae blasts, swallowing of small bodies, and streams of gas and stars feeding material into the nucleus,” Schawinski said.
Unfortunately, the process powering the quasars and their black holes lies below the detection of Hubble making them prime targets for the upcoming James Webb Space Telescope, a large infrared orbiting observatory scheduled for launch in 2018.
Crab Nebula Superflares
Scientists think the flares occur as the intense magnetic field near the pulsar undergoes sudden restructuring. Such changes can accelerate particles like electrons to velocities near the speed of light. As these high-speed electrons interact with the magnetic field, they emit gamma rays.
To account for the observed emission, scientists say the electrons must have energies 100 times greater than can be achieved in any particle accelerator on Earth. This makes them the highest-energy electrons known to be associated with any galactic source. Based on the rise and fall of gamma rays during the April outbursts, scientists estimate that the size of the emitting region must be comparable in size to the solar system.
Researchers using the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope have developed a new method to detect a special class of stellar remnant, known as pulsars. A pulsar is a special type of neutron star, which spin hundreds of times per second. When the intense spin is combined with beams of energy caused by intense magnetic fields, a “lighthouse” pulse is generated. When the “lighthouse” beam sweeps across Earth’s field of view, the object is referred to as a pulsar.
Led by Matthew Kerr (Kavli Institute for Particle Astrophysics and Cosmology), and Fernando Camilo (Columbia University), a research team recently announced a new method for detecting pulsars. How will Kerr’s research help astronomers better understand (and locate) these small, elusive stellar remnants?
Every three hours, the LAT surveys the entire sky, searching for the high energy signatures associated with gamma-ray outbursts. In general the energy levels of the photos detected by the LAT are 20 million to over 300 billion times as energetic as the photons associated with visible light.
By combining observations from the LAT and data obtained from the Parkes radio telescope in Australia, the team is able to detect pulsar candidates. The team’s approach combines a “wide area” approach of an all-sky telescope like the LAT with the sensitivity of a radio telescope. So far, the team’s discovery of five “millisecond” class pulsars, including one unusual pulsar has proven their technique to be successful.
The unusual pulsar, officially named PSR J0101–6422, had an additional 35 days of study devoted to better understanding its properties. Once the radio pulsation period and phase were determined, an incredible amount of data, including data on its gamma-ray pulsations was obtained. Using the data, the team was able to determine PSR J0101–6422 is roughly 1750 light-years away from Earth, and has an unusual light curve which features a “sandwich” of two gamma-ray peaks with an intense radio peak in the center, like a cosmic ham sandwich.
The team was unable to explain the phenomenon with standard pulsar emission models.which the team could not explain with standard geometric pulsar emission models, and have proposed that J0101–6422 is a new hybrid class of pulsar that features radio emissions that originate from low and high altitudes above the neutron star.