Guide to Radiation Doses

Guide to Radiation Doses

Randall Munroe of XKCD put together this fascinating chart of the “ionizing radiation dose a person can absorb from various sources;” from using a cell phone to CT Scans to being at Chernobyl and Fukushima when disaster struck.

Munroe received help from Ellen, a Senior Reactor Operator at the Reed Research Reactor, and you can find a list of the sources used here.

As far as accuracy, Munroe also adds:

“It’s for education purposed only. If you’re basing radiation safety procedures on an internet PNG image and things go wrong, you have no one to blame but yourself.”

radiation-dose-chart-infographic-xkcd

First Hundred Thousand Years of Our Universe

First Hundred Thousand Years of Our Universe

Mystery fans know that the best way to solve a mystery is to revisit the scene where it began and look for clues. To understand the mysteries of our universe, scientists are trying to go back as far they can to the Big Bang. A new analysis of cosmic microwave background (CMB) radiation data by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) has taken the furthest look back through time yet – 100 years to 300,000 years after the Big Bang – and provided tantalizing new hints of clues as to what might have happened.

“We found that the standard picture of an early universe, in which radiation domination was followed by matter domination, holds to the level we can test it with the new data, but there are hints that radiation didn’t give way to matter exactly as expected,” says Eric Linder, a theoretical physicist with Berkeley Lab’s Physics Division and member of the Supernova Cosmology Project. “There appears to be an excess dash of radiation that is not due to CMB photons.”
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Our knowledge of the Big Bang and the early formation of the universe stems almost entirely from measurements of the CMB, primordial photons set free when the universe cooled enough for particles of radiation and particles of matter to separate. These measurements reveal the CMB’s influence on the growth and development of the large-scale structure we see in the universe today.

 

Linder, working with Alireza Hojjati and Johan Samsing, who were then visiting scientists at Berkeley Lab, analyzed the latest satellite data from the European Space Agency’s Planck mission and NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), which pushed CMB measurements to higher resolution, lower noise, and more sky coverage than ever before.

“With the Planck and WMAP data we’re really pushing back the frontier and looking further back in the history of the universe, to regions of high energy physics we previously could not access,” Linder says. “While our analysis shows the CMB photon relic afterglow of the Big Bang being followed mainly by dark matter as expected, there was also a deviation from the standard that hints at relativistic particles beyond CMB light.”

Linder says the prime suspects behind these relativistic particles are “wild” versions of neutrinos, the phantomlike subatomic particles that are the second most populous residents (after photons) of today’s universe. The term “wild” is used to distinguish these primordial neutrinos from those expected within particle physics and being observed today. Another suspect is dark energy, the anti-gravitational force that accelerates our universe’s expansion. Again, however, this would be from the dark energy we observe today.

The microwave sky as seen by Planck. Mottled structure of the CMB, the oldest light in the universe, is displayed in the high-latitude regions of the map. The central band is the plane of our galaxy, the Milky Way. (Courtesy of European Space Agency)

The microwave sky as seen by Planck. Mottled structure of the CMB, the oldest light in the universe, is displayed in the high-latitude regions of the map. The central band is the plane of our galaxy, the Milky Way. (Courtesy of European Space Agency)

“Early dark energy is a class of explanations for the origin of cosmic acceleration that arises in some high energy physics models,” Linder says. “While conventional dark energy, such as the cosmological constant, are diluted to one part in a billion of total energy density around the time of the CMB’s last scattering, early dark energy theories can have 1-to-10 million times more energy density.”

Linder says early dark energy could have been the driver that seven billion years later caused the present cosmic acceleration. Its actual discovery would not only provide new insight into the origin of cosmic acceleration, but perhaps also provide new evidence for string theory and other concepts in high energy physics.

“New experiments for measuring CMB polarization that are already underway, such as the POLARBEAR and SPTpol telescopes, will enable us to further explore primeval physics, Linder says.

Linder, Hojjati and Samsing are the authors of a paper describing these results in the journal Physical Review Letters titled “New Constraints on the Early Expansion History of the Universe.” Hojjati is now with the Institute for the Early Universe in South Korea, and Samsing is with the DARK Cosmology Centre in Denmark.

This research was primarily supported by the DOE Office of Science.

For more about the Supernova Cosmology Project go here

Editors note: Original article can be found here.

Credit:  Berkeley lab

Dark Flow

Dark Flow

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The universe is far stranger than anything we can truly contemplate. From the big bang, black holes, dark matter, giant diamond stars, and exoplanets coated in burning ice, one truly doesn’t have to look too far to find something that is mind-boggling or hard to comprehend. On today’s list of W-T-F’s, is a relatively new cosmic phenomena called “dark flow.” (I again, find it kind of ironic that we use the word ‘dark’ so often. Each time it usually means ‘we have no idea, really.’)

The “Observable” Universe —

Anyhow, the actual universe is divided into two parts. First, there is the ‘observable’ universe, which spans approximately 93 billion light-years in diameter. Then we have the actual universe, which has no set diameter as there is still quite a big debate brewing in the scientific community concerning whether or not the universe is finite or infinite. We may never know, as we can only see light from distant objects that have had the time to travel from its original position to our own planet, which limits exactly how much we can see of the universe. One can argue that, based on its flat geometry, the universe continues infinitely in all directions, just as we are hindered by the sea’s horizon as we gaze out in all directions here on Earth. But either way, we know something more exists beyond our cosmic horizon, we are just unable to detect exactly what lies just beyond it.

However gravity is a strange beast, albeit a useful one to us here on Earth because it provides certain clues to the existence of objects that are very small, difficult to spot, or perhaps even entirely invisible (like black holes). Rocky Earth-like exoplanets are a good example of gravity’s usefulness in astronomical observation. Most exoplanets we’ve discovered thus far were found through the radial velocity method, which observes tell-tell ‘wobbles’ that happen as a planet tugs on its parent star. It is through that same phenomena that we are able to determine there is more beyond the scope of what we can see… since gravity is still applicable on a large-scale in the universe, just as it is on a small-scale.

The ‘Dark Flow’ Cosmic Quandary —

NASA’s Wilkinson Microwave Anisotropy Probe’s (WMAP) spent an entire three years studying the universe’s cosmic microwave background radiation, which is the remnants from the radiation created only 380,000 years after the big bang. It also developed a catalog of deep space clusters, some of which are more than 3 billion light-years from Earth. When scouring through the data collected, the team spotted out more than one hundred galaxy clusters that are lit up by hot, x-ray emitting gases. Our theories on the CMB basically say that the waves that sprung from the big bang should pass through said galaxy clusters and change in predictable ways under certain scenarios, including if the galaxy is moving relative to the background glow. The WMAP was developed to test this, which is known as kinematic Sunyaev-Zel’dovich (SV) effect, but physicists found something else altogether that brought more questions to light than it answered.

What did they find? —

The clusters are traveling more than 2 million miles per hour, into an expanse of about 20-degrees of sky into a line from our solar system, to the constellations of Centaurus and Hydra. Furthermore, the trend is not a statistical fluke, as it continues to hold steady throughout interstellar space instead of bucking black to normal speeds and distributions.

“It’s the same flow at a distance of a hundred million light-years as it is at 2.5 billion light-years and it points in the same direction and the same amplitude. It looks like the entire matter of the universe is moving from one direction to the next,” says Alexander Kashlinsky, the team leader of the study from NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

What does it mean?

This baffling observation suggests that something created only a fraction of a second after the big bang (moments before inflation, when the universe began to expand outward at incredible speeds) is involved, exerting a gravitational force on the clusters from just beyond the scope of our observable universe, but what? “We can only say with certainty that somewhere very far away the world is very different than what we see locally. Whether it’s ‘another universe’ or a different fabric of space-time we don’t know,” Kashlinsky continued.

One theory put forth about the observations fits theoretical models purported by string theory, of how a ‘sister’ or ‘twin’ universe may be pulling at our own, which would account for what we’re observing with the clusters traveling so quickly. Regardless, the structure is not thought to be a part of our own simply because we haven’t observed anything that could have an immeasurable mass to accomplish anything similar to what we’re observing here. It is possible though, that there is a yet-to-be-seen neighboring part of our universe that underwent inflation much differently than our section did. Interestingly, maybe the answer to this riddle could potentially overhaul our theories about dark matter and dark energy, perhaps? It’s hard to say, but it does present some interesting questions.

“If our universe is all that’s there, then the liquid in the box shouldn’t be sliding. Whatever is pulling it has to be bigger than the size of the box,” she said. “There is a structure beyond the horizon of our universe and that structure is exerting a force on our universe and creating this flow.”

By Jaime Trosper

Sources & Further Reading:

“Mysterious Cosmic ‘Dark Flow’ Tracked Deeper into Universe:”
http://www.nasa.gov/centers/goddard/news/releases/2010/10-023.html

“The Observable Universe:”
http://tinyurl.com/OBSERVE-fqtq-fb

“Cosmic Microwave Background:”
http://tinyurl.com/CMBr-fqtq-fb

Image Source: NASA/Goddard/A. Kashlinsky, et al.

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 Unported License.

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The current widely held theory of the universe.

The current widely held theory of the universe.

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The current widely held theory of the universe is that at some point, around roughly 13.7 billion years ago, everything that is, was and will ever be was packed into a tight little package from which sprung the big bang, which then violently hurtled everything we see into existence. To some scientists, 13.7 billion years isn’t enough time to get to where are are. One particular physicist believes he can prove that things weren’t that simple. In fact, drawing from the only evidence left behind after the big bang, he believes that evidence found in the cosmic microwave background (which is believed to have been thrust into existence when the universe was just 300,000 years old) proves that the big bang wasn’t the beginning, but it was one in a series of cyclical big bangs. Each of which spawned its own universe.

Sir Roger Penrose estimates that our universe is not the first, nor will it be the last to spawn from a dense mass of highly ordered everything, into the complex universe we see around us. The current big bang model doesn’t supply a reason as to why a low entropy, highly ordered state existed at the birth of our universe unless things were set in order before the big bang occurred. In Penrose’s theory, each universe returns to a state of low entropy as it approaches its final days of expanding into eventual nothingness. By virtue, black holes spend their cosmic lifetimes working to scrub entropy from the universe. As the universe nears the end of its expansion, the black holes evaporate or gobble one another up, thus setting things back into a state of order. The universe is then unable to expand any further so it collapses back in on itself as a highly ordered system that’s ready to trigger the next big bang.

The current model of the universe says that any temperature variations in the CMB should be random, but Penrose claims he has found very clear concentric circles within it that suggests there are regions where the radiation has much smaller temperature ranges. To him, these posits are spherical evidence of the gravitational effects of black hole collisions during the previous universe.

Of course, if his theory was able to withstand the test of time and rigorous scientific testing, it still doesn’t explain where the first version of the universe spawned from or how the first black hole formed. Nor does his theory fit in with the standard inflation models. Still, it’s interesting to ponder.

Sources & More Information:

“Penrose claims to have glimpsed universe before Big Bang:”
http://physicsworld.com/cws/article/news/2010/nov/19/penrose-claims-to-have-glimpsed-universe-before-big-bang

By Jaime Trosper