Swirls in remnants of big bang may hold clues to universe's infancy

Dec 13, 2013
Physics Review magazine has named research results published earlier this year by the South Pole Telescope collaboration as one of the top 10 physics breakthroughs of 2013. Credit: Daniel Luong-Van

South Pole Telescope scientists have detected for the first time a subtle distortion in the oldest light in the universe, which may help reveal secrets about the earliest moments in the universe's formation.

The scientists observed twisting patterns in the polarization of the —light that last interacted with matter very early in the history of the , less than 400,000 years after the big bang. These patterns, known as "B modes," are caused by , a phenomenon that occurs when the trajectory of light is bent by massive objects, much like a lens focuses light.

Early today, Physics World magazine heralded the result as one of the top 10 physics breakthroughs of 2013.

A multi-institutional collaboration of researchers led by John Carlstrom, the S. Chandrasekhar Distinguished Service Professor in Astronomy & Astrophysics at the University of Chicago, made the discovery. They announced their findings in a paper published Sept. 30, 2013, in the journal Physical Review Letters—using the first data from SPTpol, a polarization-sensitive camera installed on the telescope in January 2012.

"The detection of B-mode polarization by South Pole Telescope is a major milestone, a technical achievement that indicates exciting physics to come," Carlstrom said.

The cosmic microwave background is a sea of photons (light particles) left over from the big bang that pervades all of space, at a temperature of minus 270 degrees Celsius—a mere 3 degrees above absolute zero. Measurements of this ancient light have already given physicists a wealth of knowledge about the properties of the universe. Tiny variations in temperature of the light have been painstakingly mapped across the sky by multiple experiments, and scientists are gleaning even more information from polarized light.

Light is polarized when its electromagnetic waves are preferentially oriented in a particular direction. Light from the cosmic microwave background is polarized mainly due to the scattering of photons off of electrons in the early universe, through the same process by which light is polarized as it reflects off the surface of a lake or the hood of a car. The polarization patterns that result are of a swirl-free type, known as "E modes," which have proven easier to detect than the fainter B modes, and were first measured a decade ago, by a collaboration of researchers using the Degree Angular Scale Interferometer, another UChicago-led experiment.

B modes can't be generated by simple scattering, instead pointing to a more complex process—hence scientists' interest in measuring them. Gravitational lensing, it has long been predicted, can twist E modes into B modes as photons pass by galaxies and other massive objects on their way toward earth. This expectation has now been confirmed.

To tease out the B modes in their data, the scientists used a previously measured map of the distribution of mass in the universe to determine where the gravitational lensing should occur. They combined their measurement of E modes with the mass distribution to provide a template of the expected twisting into B modes. The scientists are currently working with another year of data to further refine their measurement of B modes.

The careful study of such B modes will help physicists better understand the universe. The patterns can be used to map out the distribution of mass, thereby more accurately defining cosmologically important properties like the masses of neutrinos, tiny elementary particles prevalent throughout the cosmos.

Similar, more elusive B modes would provide dramatic evidence of inflation, the theorized turbulent period in the moments after the when the universe expanded extremely rapidly. Inflation is a well-regarded theory among cosmologists because its predictions agree with observations, but thus far there is not a definitive confirmation of the theory. Measuring B modes generated by inflation is a possible way to alleviate lingering doubt.

"The detection of a primordial B-mode polarization signal in the microwave background would amount to finding the first tremors of the Big Bang," said the study's lead author, Duncan Hanson, a postdoctoral scientist at McGill University in Canada.

B modes from inflation are caused by gravitational waves. These ripples in space-time are generated by intense gravitational turmoil, conditions that would have existed during inflation. These waves, stretching and squeezing the fabric of the universe, would give rise to the telltale twisted polarization patterns of B modes. Measuring the resulting would not only confirm the theory of inflation—a huge scientific achievement in itself—but would also give scientists information about physics at very high energies—much higher than can be achieved with particle accelerators.

The measurement of B modes from gravitational lensing is an important first step in the quest to measure inflationary B modes. In inflationary B mode searches, lensing B modes show up as noise. "The new result shows that this noise can be accounted for and subtracted off so that scientists can search for and hopefully measure the inflationary B modes underneath," Hanson said. "The lensing signal itself can also be used by itself to learn about the distribution of mass in the universe."

Explore further: Long-sought pattern of ancient light detected

More information: "Detection of B-mode polarization in the Cosmic Microwave Background with Data from the South Pole Telescope," by Duncan Hanson and the South Pole Telescope Collaboration. Physical Review Letters, Vol. 111, Issue 14, 2013.

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k_m
1.8 / 5 (5) Dec 13, 2013
So, that is light "aimed" at us, right?

What about light that isn't aimed at us and maybe misses us by a few hundredth arc-seconds?
Zephir_fan
Dec 13, 2013
This comment has been removed by a moderator.
Whydening Gyre
2.3 / 5 (6) Dec 13, 2013
And that Zeph-skippy was one of the stupidest answers I have ever heard on here. Sit down, shut-up and let the smart people give the right answers.
Zephir_fan
Dec 13, 2013
This comment has been removed by a moderator.
davidivad
1 / 5 (3) Dec 14, 2013
They are more concerned with measuring the emissions they can see. sorry, that's all i have.
Whydening Gyre
2.7 / 5 (7) Dec 14, 2013
And that Zeph-skippy was one of the stupidest answers I have ever heard on here. Sit down, shut-up and let the smart people give the right answers.


I'm looking, but I don't see a smart answer with your name on it? Did the light miss you too?

Interestingly enough, haven't seen any with yours on it, either...
It appears your head is so far up yer own ass, that it missed you, too...
davidivad
1.8 / 5 (5) Dec 14, 2013
how about this... you only need to see the emissions coming right at you. you do not want to see anything else because that is how pictures are made. imagine a camera without a lense. you would not get a picture of any value that way.
dav_daddy
2 / 5 (5) Dec 14, 2013
So, that is light "aimed" at us, right?

What about light that isn't aimed at us and maybe misses us by a few hundredth arc-seconds?


It might help if you could be a little more clear about what exactly you asking?

If you mean the light they are not focusing on, or the emitted light they not receiving?

In either case you can think of it like looking at a string of Christmas lights. You can look at all of them or you can focus on just one light. If you focus on 1 light it doesn't matter that you aren't capturing 100% of the light bulbs light with your eyes? In fact the light that misses you by just a hair can be seen by your friend standing next you. You are capturing different photos with your eyes but you both see exactly the same thing.
antialias_physorg
4.8 / 5 (4) Dec 14, 2013
What about light that isn't aimed at us and maybe misses us by a few hundredth arc-seconds?

Erm...what about it?

The light we get just happens to hit us. Other photons (the vast majority) miss us. Since our position in this universe is presumably not special there's no reason to assume that light that passes us by displays modes in a significiantly different manner.
k_m
1 / 5 (4) Dec 14, 2013
My thought was would looking at the same point from multiple, different angles help tease out more of what's being looked for...? Or would it invalidate what's been detected?
davidivad
1 / 5 (4) Dec 14, 2013
in a sense, this is what they are doing. they are looking at the angles of the light.
k_m
1 / 5 (4) Dec 14, 2013
I get the polarization thing, but what's apparently going over my head (literally, maybe) is that they only have one viewing angle, or only so few that those could be considered the same angle due to the literal degrees of separation being so close, and the distance so far, they could be tantamount to 0.

k_m
1 / 5 (4) Dec 14, 2013
What about light that isn't aimed at us and maybe misses us by a few hundredth arc-seconds?

Erm...what about it?

The light we get just happens to hit us. Other photons (the vast majority) miss us. Since our position in this universe is presumably not special there's no reason to assume that light that passes us by displays modes in a significiantly different manner.

Does that, what you've just explained, maybe explain why we don't see or detect a lot of the matter in the Universe?

Just asking.
k_m
1 / 5 (4) Dec 14, 2013
Assuming 360 degrees in three dimensions, means there are more than 46656000 different directions a photon can travel, and for us to detect "that" photon is appropriately less likely.

So we sit here, look at what we can see, and are completely oblivious and ignorant of what we can't see, simply by virtue of our vantage point.
antialias_physorg
not rated yet Dec 14, 2013
Does that, what you've just explained, maybe explain why we don't see or detect a lot of the matter in the Universe?

No, it doesn't.

Just asking.

Just answering.
k_m
2.7 / 5 (7) Dec 14, 2013
Re: My being called "Skippy"... that must be the taste left in your mouth after receiving that natural, creamy, salty goodness you get in your mouth... that flavor you love to hate so much you can't stop talking about it and accuse everyone of having it just so you can get it in your mouth again.

Yes, little baby gets the nom nom noms.

k_m
1.8 / 5 (5) Dec 14, 2013
Does that, what you've just explained, maybe explain why we don't see or detect a lot of the matter in the Universe?

No, it doesn't.

Okay. Please explain.

We can see in most every direction from here, but we can't detect everything sent in every direction from everywhere else since most of that wasn't directed at us.
Zephir_fan
Dec 14, 2013
This comment has been removed by a moderator.
k_m
2.6 / 5 (5) Dec 14, 2013

Okay Skippy, why don't you just ask another stupid question,

And why don't you give a smart, knowledgeable, intellectual, informed answer... for a change?
Zephir_fan
Dec 14, 2013
This comment has been removed by a moderator.
k_m
2.3 / 5 (6) Dec 14, 2013
I gave you the only right answer to your original answer. The photons that miss you, miss you.

Well, no shit Sherlock, which is why I asked about those photons.

Are you so dense so as to think no one else is as intelligent as you?

Never mind, the answer to that question is obvious.
Zephir_fan
Dec 14, 2013
This comment has been removed by a moderator.
k_m
2.6 / 5 (5) Dec 14, 2013
Yeah, okay.
Things you don't see don't have any influence on that which you can see and measure.

Makes sense....
Zephir_fan
Dec 14, 2013
This comment has been removed by a moderator.
ut2262
1 / 5 (2) Dec 15, 2013
The photons that miss you, miss you. They don't turn around and try to hit you again, they just keep going until they hit someone else.
If you would be Zephir fan, you would think, how such situation will appear at the water surface. Well, at the water surface the waves spread in regular circles first. But at the sufficient distance they get scattered into underwater and their path will not be straight anymore - it will spread in random "swirls" in turbulent way, because at the very large distance scale even the density of fluctuations is not fully stable.

At the very end, all ripples would get scattered into underwater, where the energy spreads via sound waves. These waves are much faster, than these surface ones and they can spread in arbitrary direction. So that there is non-zero possibility, we could perceive the weak indeterministic echo of the distant surface splash scattered with Brownian noise just at the place, where the surface ripple has been sent originally.
antialias_physorg
3 / 5 (2) Dec 15, 2013
Okay. Please explain.

We can see in most every direction from here, but we can't detect everything sent in every direction from everywhere else since most of that wasn't directed at us.

Simple. Look at a chair. Most of the photons bouncing off it don't hit you - yet you still can see the chair. (Similar with a star - most of the photons emanating from it don't hit Earth. Some still do. By these we can see that a star is there and what size it is)

As for mass that emanates so few photons that we can't see it directly (or as in the case of dark matter or black holes themselves no photons): We can see how it affects photons travelling close to it from other sources by gravitational lensing.

in short: seeing the effects of mass is enough to know mass is there. You don't need to se every single photon emanating from a piece of mass to know about it and be able to characterize it.
Zephir_fan
Dec 15, 2013
This comment has been removed by a moderator.