I am Dr. Randol Aikin, co-author and collaborator on BICEP2- the team that announced the discovery of "B-modes" yesterday, the ancient echoes of the Big Bang. Ask me anything!

By the by... Anybody wanting to check out our results should go to bicepkeck.org

So what does this discovery mean for inflation theory and will it now become the prevailing model?

What's next for inflation theory?

As a physics/cosmology layman - what does this mean for how I understand the universe?

Inflation theory has been the prevailing model for a while now... The thing is, Inflation Theory is actually a whole class of theories. We can use this detection to begin to rule out classes of inflation.

This means that what we've long suspected - that the universe expanded faster than the speed of light at just a fraction of an instant after the big bang - is right.

that the universe expanded faster than the speed of light at just a fraction of an instant after the big bang

Again, excuse my very layman knowledge here but I thought that one of the most cardinal rules of physics was that nothing can be faster than the speed of light. Do we know what made that rapid expansion possible and why it doesn't fit within conventional laws of physics?

The short answer is that relativity tells us that particles can't move faster than the speed of light. But that speed limit doesn't apply to space itself. Inflation theory is about the expansion of space itself, which means no "stuff" moves faster than the speed of light.

Could this get us any closer to finding out what happened before the Big Bang?

To give a bit more of a complete answer, folks that work in this field in general skirt questions about "before" the Big Bang. In part, this is because different people mean different things when they say "Big Bang". Some people consider the process of inflation (a period of rapid expansion in the early universe) is itself the big bang. Others will tell you that the big bang is the thing that gave rise to inflation. Our discovery will absolutely help us understand the process of inflation and what gave rise to inflation. I still hesitate to say "yes" though...

It will no doubt give rise to plenty of theories :) As an experimentalist though, I think these theories will only be useful if we can observe their consequences.

What was your favorite "go to" food while working on something as extensive as this?

Tacos, preferably al pastor, in large quantities and with Dr. Pepper. Tacos go in, science comes out.

Most of us will never be present for a discovery as incredible as this. Could you just explain what that moment was like (how it felt) when you and your team found concrete evidence of B-modes after years of tireless work?

There was no one single moment. You first assume that the signal is not real and you've done something horribly wrong. Then over time, you get closer and closer to convincing yourself that you haven't screwed up and you've actually discovered something real!

Excuse me if this is a silly question, but how do you tell if a B-mode signal is a B-mode signal if you've never actually gotten a signal from one before?

Totally! Not a silly question at all. The great part about this experiment is that a bunch of really smart theorists were able to tell us what the signal should look like. We go out (to the south Pole) and measure the thing, and we actually see what the theory predicts! If you want a more technical answer, it's that the B-mode isn't a signal so much as a signature. It's a particular pattern of the polarization of the light from the early universe.

Did the team take pictures kissing their biceps in front of bicep2? And what can that teach us about science?

One member of the team sure did... This teaches us to pick better names for our projects, because some day those names may show up on the front page of the NYT.

Dr. Aikin, I have a couple questions for you:

1) Was there anything surrounding the universe before the rapid expansion of space? Or is that question impossible to answer because space itself came from the big bang?

2) Could you explain in layman's terms what is inflation theory, its implications, and what kind of experiments were done to prove the inflation theory?

3) If all the energy and matter is conserved in the universe, then where did it all come from? I.e where did the initial singularity of the big bang come from?

Thanks a bunch for doing this AMA!

1) Good question, but tricky to answer... What we generally consider to be the "universe" is the stuff that we can actually see and observe. We generally call this stuff "causally connected". Inflation theory tells us that before inflation began, the universe (the stuff we're causally connected to) was big. Then the universe expanded. A LOT. At the end of inflation, the region of the universe that was causally connected was tiny compared to before inflation. Does that help? 2) kinda answered by 1... 3) This is one of the big discoveries we're excited about. The evidence for inflation theory gives support to the existence of a new source of energy, which we call the Inflaton. The Inflaton is what sets all of this stuff in motion. I know that's not a very satisfying answer...

Hello Dr. Aikin, welcome to Reddit!

1. What do you guys believe to be the external source of energy? Photons?

2. I'm also guessing we still have no clue or hypothesis on what the early universe was expanding into, is this still the case?

1. There's no external source of energy that drives inflation. The energy is this thing called the "inflaton". Physicists call this a "scalar field", but it's reasonable to just think about it as a new type of particle that fills the early universe. This is the thing that's predicted to drive inflation.
2. For one of those mind blown moments, don't think about the universe expanding into anything. Instead think of the universe itself as expanding. I know that's probably not very helpful... The main point is that the picture of a 3D sphere expanding out isn't really the right picture to have. The expansion is taking place in 4D, and space itself is expanding.

What does this work tell us about gravity that we didn't know before?

So far, no one has really been able to put together a complete and convincing framework for combining quantum mechanics and gravity. Our discovery tells us that quantum gravity is a real thing.

If you're still going, could you possibly elaborate on this? How do your results support quantum gravity?

The story goes something like this: Inflation is a process that stretches the universe by many, many orders of magnitude, right? So that means that very small scales (quantum scales) get stretched to astrophysical scales. We have found evidence of the effects of gravitational waves at astrophysical scales around 400,000 years after the big bang. Theory tells us that these gravitational waves must have been created at the quantum scale and stretched by inflation (the theoretical reasons for that are somewhat complicated). The fact that we see the effects of these things tells us that there must have been quantum fluctuations in the gravitational field before inflation. In other words, quantum gravity. Does that help?

Is there such thing as "outside" the universe? Could you ever get to some kind of edge, and what would be beyond it?

So at risk of sounding like a total... not sure what... I'd say that the "edge" of the universe is in some sense time. The size of the universe - the stuff to which we are "causally connected" (meaning the stuff that we can see, essentially) grows with time. This is because light takes a finite amount of time to travel. So the longer we wait, the further it travels. In that sense the "edge" in some sense is traveling outwards in time.

There appears to be a blog entry with a reaction from Planck.

I don't speak French and the google translate is rough. But, it appears that some mild feelings of skepticism are expressed. For example, '[BICEP's] confidence in their result "is a bit exaggerated."' The blog also mentions that BICEP studied a very small section of the sky while Planck is more exhaustive. While the blog entry seems to agree that evidence is strong for r > 0, they seem unconvinced of the BICEP2 team's specific claims.

1. Do you feel that their skepticism is warranted?
2. Would you be surprised if Planck publishes tensor-to-scalar ratio substantially different than BICEP2's?
3. If they were to do so, what are the steps to resolve the discrepancy?

Most of all, congratulations on the huge announcement and thanks for the incredible work!

1. Skepticism is absolutely warranted! We count on our competitors to get out there and to try to prove us wrong. That's the beauty of science. I hope these folks read the papers carefully.
   
2. It depends on what "substantially different" means. If they don't see anything, it'll be my turn to be the skeptic.
3. It's all about instrumental systematics.

This may be a dumb question that comes from one of those hobbyists that think they know what they're talking about, but...

Is it possible that the Inflaton is the source of Dark Energy or cosmological constant?

Not a dumb question at all! There is a lot in common with dark energy and inflation and they lead to strikingly similar evolutionary mechanics. There is still no commonly accepted theory for a firm connection between the two, but many of us have a hunch that they must be connected... If nothing else, the theoretical framework for describing one will certainly help understand the other.

Hello Dr. Aikin!

How long does it take to perform this kind of experiment. How many collaborators were there on this project? Was this something that was difficult to coordinate? Why does the experiment have to be performed at the South Pole?

Thanks!

We began designing the experiment in 2006. We sent the telescope to the South Pole in 2009, took data until 2012, and published yesterday. The wider BICEP2 team consists of lots of folks - more than 20, less than 40 or so.

We go to the South Pole because the atmosphere is thin and dry - perfect for observing the microwave radiation we're after.

In one of your earlier answers you stated that "...quantum gravity is a real thing." Could you expand on that a little please.

I'll do my best... When you squeeze particles, they behave quantum mechanically. This means that they wiggle - they don't maintain a single point in space - their behavior is not strictly deterministic. Our discovery suggests that gravity acts the same way. At tiny scales, gravity wiggles (behaves quantum mechanically) just like light, electrons, protons, leaps, etc.

Is it possible for you to explain your discovery in layman's terms?

I'll have a go at least... Our discovery supports the theory of Inflation. Inflation explains the "Bang" in the Big Bang. Don't think of an explosion - instead think of something rapidly expanding. I like to think of some hot white point expanding - doubling in size over and over and over again. And finally when it's done, the universe is filled with hydrogen and helium and all the stuff that will one day become planets, stars, and galaxies. Our discovery yesterday tells us (for subtle reasons) that inflation theory - this radical picture - is actually right.

Okay, that's lucid enough- thanks for the response.

Was this discovery replacing an old model, or explaining uncharted scientific territory? If the former, what did people previously think?

Uncharted territory in a lot of ways. We're talking about the physics of the universe that is much higher energy than anything we can recreate on earth.

Not sure if you are still around...

One of the press release articles for your discovery used the term "imprinted". Can you give me an ELI5 version of "imprinted"? What does it mean that "all we see was imprinted at that moment?"

ELI5 = Explain it like I'm 5. (Not sure if you're a regular redditor and/or familiar with the lingo)

Congratulations on this!!

I'll do my best :) So the light that we observe comes from a particular snapshot in time, from when the universe was about 400,000 years old (extremely young). In that short period of time, the universe went from being totally opaque to totally transparent. After the universe became transparent, the light from the early universe has been traveling, uninterrupted, until it hits one of our telescopes. So by observing that light, we can actually make precise measurements about what was going on at very early times. Welp, pretty sure I failed.

Alright - one more crack. The way that the signal we measure is "imprinted" is that the physics we're trying to verify has an effect on the light from the early universe. It changes the pattern of light really early on, and in a subtle way. But that light then travels for billions of years, carrying that "imprint" along with it. And since the light has been pretty much undisturbed during it's journey, we can measure the effects. Aaaand I think I failed again.

Would you be willing to do an interview for my series on "Before They Were Scientists"? (http://www.yourwildlife.org/category/before-they-were-scientists/)

Absolutely - as soon as I figure out what that is :)

What's your favorite kind of pop-tart?

Strawberry. They can keep the rest.

With the frosting, right? Come on now.

Absolutely not. What do I look like, an animal?

who wrote the theory ?

Generally credited to two guys - Alan Guth and Andrei Linde. Two stand-up dudes.

How much work goes into a discovery like this, and how often before this discovery did you find your work redundant/dull?

We had a huge discussion about this topic in astronomy today, and it made the class much more interesting! Thanks for the AMA!

Great question. The fact is, you can't count on a discovery like this. My advisor at Caltech often called this project a "wild goose chase". The only thing you can count on is knowing that you're working with the best and the brightest, and are a better person for it.

Hello, you're amazing. I'm curious about the lifestyles of spectacular people so I'd like to know a few things. Like:

What do you do in your free time? What are your hobbies? And, are you always thinking about science?

Free time?? Hobbies?? Kidding. Most of my free time/hobbies involves tackling some activity that I suck at, try to get better at it, get to the point where I don't suck at it so much, then move on to something new. Definitely not always thinking about science, but after years in physics grad school, it's pretty hard not to think like a scientist all the time...

Dr Aikin, thanks for doing this awesome and very timely IAmA. Could we use this or a similar technique to see the effects of inflation on a multiverse? Does this finding shed any more light on the concept of a multiverse? Thank you!

I think it depends on who you ask. I hope I'm not putting words into anyone's mouth, but I think the guys that invented inflation theory will tell you that the case for a multiverse is made stronger with the validation of inflation. We can use this technique to learn a lot about inflation, but until we understand the details of inflation, it's hard to say what we'll learn experimentally about multiverse models.

Also, don't forget, inflation is a crazy idea just on it's own, even before you start throwing in multiple universes.

[deleted]

From an early education standpoint, absolutely. At the academic research level, USA #1.

Thank you for doing this AMA!

I've been seeing a lot of articles in the news saying that this recent discovery "proves that the Big Bang happened." I was under the impression that the fact of the Big Bang has long been established, and this discovery is proof of rapid inflation in the early Universe. Is this accurate?

As someone who is interested in science but knows very little about it, I just wanted to clarify this point. Thanks again.

That's spot-on. We observe the Cosmic Microwave Background. When this was discovered in the 60's, many people took this to be "proof" of the Big Bang. That discovery and subsequent measurements of the Cosmic Microwave Background, while proving the basic tenants of Big Bang theory, has raised more questions than it's answered. But yesterday we got a little bit closer.

Awesome. One more question: What's the next big experimental verification of a scientific theory that you think will be most important for modern physics and want to see happen most in the near future?

Direct detection of the dark matter. The current prevailing theory is that dark matter is made up of WIMPs - weakly interacting massive particles. I think scientists are very close to actually measuring one of these things and setting a cross section. That would be HUGE.

Where should I go to college? I am currently deciding between University of Virginia and University of Richmond.

University of Colorado, Boulder. Go buffs.

Pick a place where you have lots of room to grow and to take lots of classes you didn't expect you'd enjoy. That's how I found physics and astronomy.

Is this the discovery of gravity waves, and can you tell us more about them?

Also, why did they affect light polarization? The universe wasn't even permeable to light.

Awesome question. This is not a direct detection of gravity waves. We'll leave that to the folks working on the LIGO experiment. Instead, we see the indirect effects of gravity waves. The polarization of the light from the cosmic microwave background is generated by hot and cold patches in the early universe. The gravity waves change the hot and cold patches, so they change the polarization pattern that we observe. If you want a more complete explanation, google "Wayne Hu cosmology". He gives a really thorough explanation.

Hello Dr. Aikin, thanks for the AMA!

Not really a question directly pertinent to your recent discovery, but I'm currently a graduate student in an Astrobiology graduate program at McMaster University in Canada. Biweekly, our program meets in a "Journal Club" setting to discuss modern science and I was interested in presenting a paper you or your team have published in the past that would offer good coverage of the concepts/techniques associated with your recent discovery.

I would be totally appreciative if you know of a paper that could introduce the ideas of inflation theory/cosmic background radiation to a group of scientists who would otherwise not be involved with space physics. Being a student in organic geochemistry, I really wouldn't know where to start to find one!

Thanks for your time!

Actually, there is a really nice review article in nature: http://www.nature.com/news/all-you-need-to-know-about-gravitational-waves-1.14886 I think this does a really nice job of capturing the salient points. If you want the full gory details, you can check out our group's website, bicepkeck.org and related links.

What preceded teh big bang? since this new discovery indicates the universe does not cyclically re-create itself. where did the matter that inflated come from?

No one quite knows what preceded the big bang... We're still waiting on a complete theory that describes the physics at the highest energy scales. So turns out that energy and matter are interchangeable. During the process of inflation and subsequent expansion, different particles "freeze out", meaning the energy gets low enough that the particles, colloquially speaking, crystalize into existence.

But it would be a field, or particle that would require all of the energy in the universe to create/re-create? Is inflation a one-trick pony, happening only during the birth of a universe? Does inflation seem to support or refute the idea that our universe could have arisen from, say, a singularity (created by a black hole) from another universe? I hope I don't sound too dumb.....

Not dumb at all! My instinct is to just dodge the question by saying something like "it's exactly those types of questions we're trying to answer...", which is entirely true, but probably not very satisfying. Inflation theory itself provides a mechanism for generating the large-scale structure we observe in the universe. But, like so many other theories, it creates as many questions as it answers. Inflation theory says that the universe expanded out of quantum fluctuations. But describing what that pre-inflationary universe actually looks like still hasn't happened.

What helps you wrap your head around measurements so astoundingly small, and measurements so incredibly large? From Planck time to the age of the universe... How do you approach comprehending such extremes?

The trick seems to be to bury your head in the sand :) Instead of trying to solve the mysteries of the universe, you instead go out and try to measure one thing very, very carefully. In this case, it meant three trips to the South Pole, which helped.

will this proof help to explain dark matter as well as the possible stop in in expansion of the universe?

I think it's safe to say that this discovery does not have any direct implications for explaining what the dark matter is.

While inflationary expansion stopped long ago (just a fraction of an instant after the big bang), the universe itself is still expanding. Whether there is a connection between inflation and the dark energy that's driving the current expansion of the universe remains to be seen.

What kind of new discoveries will you and your teams findings lead to? Thanks for helping the human race take another step forward.

So we discovered evidence of this faint relic from the early universe. Just because we've seen it, it doesn't mean we totally understand it! I think there will be years of follow-up research to use this relic to understand the history of the very early universe.

Please comment upon the concept of inflation as it pertains to Black Holes. Is inflation something we believe strictly relegated to Big Bang or primordial timeframes or something that may be occurring within black holes currently? Does our recent data/observations change things in this regard?

If indeed Black Holes are creating universes via inflation, how is this reconciled/juxtaposed with Black Hole evaporation, conservation of Information, etc. ?

The statement that "Black Holes are creating universes via inflation" isn't really correct... Black holes are just regions of "extreme gravity", if you like. Our understanding of black holes today is limited by our understanding of gravity. A theoretical framework that fully describes inflation will certainly rely on a quantum description of gravity. One big problem with inflation is entropy, which in a lot of ways is similar to the conservation of information problem with black holes, and still something we need to understand.

Thank you doctor for taking the time to do this AMA:-) Does this discovery have anything to say about possible additional fundamental forces yet undiscovered (in addition to the strong, weak, EM, and gravity)?

I'll try to answer this without making any theorists cringe :) I'd say yes, though we generally don't talk in terms of forces (we instead talk about scalar fields, like the Higgs.) Now that we have some direct evidence for inflation, we also have direct evidence for a new particle and a new potential - the inflaton and the inflationary potential, respectively.

I was under the impression that inflation was driven by dark energy, and that this discovery constitutes additional evidence for its existence by proxy. Is this not the case?

Excellent question, but not the case. Inflation was driven by some scalar field that, for the time being, is called the inflaton. The dark energy that's driving the expansion of the universe today, is some other scalar field. The major difference is the energy scales. Independent of inflation, the existence of dark energy is well established. This is because the accelerated expansion of the universe has been measured to high precision.

Ugh, another god(damn) particle.

Yeah but for reals this time. We promise this is the last one.

From what I understand, this seems to have some pretty big implications for the different hypothesis there are out there on quantum gravity. Which ones are still in play? Which ones does this eliminate?

I'd pose it a slightly different way. I don't think any serious physicists deny the existence of quantum gravity. Our measurement is the first time we've been able to experimentally see the effects of quantum gravity. In other words, gravity has to behave quantum mechanically at in order for us to see the signal we observe.

The CMB radiation is essentially 14-billion year old black-body radiation that has had its wavelength stretched out with the expanding universe, right? Is this one of those rare instances where conservation of energy is technically violated? Are any other subatomic particles also expanding along with the universe, or is it just EM waves?

Nope - energy is conserved, but in a weird, relativistic kind of way. The CMB radiation is everywhere. It uniformly fills the universe. So imagine that shortly after the CMB is emitted, say 400,000 years, you draw an imaginary box and figure out how much energy is in it from the CMB. Now fast-forward in time ~14 billion years. The energy density has gone way down since the wavelength has been stretched out. But your imaginary box has also grown with the expansion of space. So the total energy in the box is conserved. (I've over-simplified a bit. In reality, your imaginary box is four-dimensional, not three. But basically the same concept holds.)

Huh, interesting. So in this particular scenario, it makes little sense to think of light as photons then, right? Since the energy of each individual photon would have had to decrease. Obviously, it makes perfect sense in the wave model.

For me at least, I tend to think of CMB photons as waves. But that has more to do with the detectors that we use than anything else...

Is it possible that your discoveries will lead to future discoveries that clash with religions like Christianity and Islam, in a sense that they prove that certain things about creationism aren't true? What are your views and predictions on this? I read an article somewhere implying this could happen, that's why I ask.

For me, science answers fundamentally different questions. Which is great news, since it means that I don't have to worry about the religious implications!

BICEP2 sounds like some type of super-cyborg bicep prosthetic. Is that what you actually make? How much are they?

Stellar question. I'll be the first to admit BICEP2 is probably not the greatest name in the world for our telescope... I would have called it the South Pole Inflationary Telescope. SPIT for short.

Southern Hemisphere Inflationary Telescope.

Polar Observatory for Observing Polarization... Dangit. Used observe twice...

What journal did you publish in?

Was there a real "a-ha" moment or was it a long process of gathering supporting data that kept you tingling the whole time?

Thanks for your time. :-)

We've submitted to the astrophysical journal, and will probably submit to some others. The way these things usually work is that you release the result and the papers at the same time, but before the actual publication comes out (the journal publication will likely take 6 months). I'd say there was no single a-ha moment. More like we spent years banging our heads against the wall, and at some point we quit banging because we convinced ourselves we had found something real. Real and extremely surprising!

Thanks so much! I've never been involved with any research worthy of releasing prior to submission. I was just wondering. I saw the website link you provided.

I think a lot of science students always imagine an "a-ha" moment, but I'm honestly a little glad to hear that even those finding results like these with some of the most advanced instrumentation in the world (it seems) have "banging your heads against the wall" times.

Thanks for your answer! Great job!

Sorry - just to be clear, we released at the same time as we submitted, but before publication.

Science is all about banging your head against the wall. Keep at it for long enough and every once in a while, you might get very, very lucky.

Does this answer if the big bang was an implosion or explosion?

This observation absolutely helps us understand the mechanics of the Big Bang. But neither picture of "implosion" or "explosion" is really what we think about... Instead, imagine an expansion of the universe, doubling in size many, many times over.

Hello Dr. Aikin, thank you for doing this AMA! After such a breakthrough, what is the next project/step you'll be working on?

Happy to do this AMA. This research is funded by the public - it's important to remember that this result, and ones like them, belong to everyone. This isn't obscure stuff just to be understood by scientists, it's meant for the public at large. (sorry... didn't actually answer the question...)

Say you're at the center of the expansion measuring particle-a moving away at 75% of the speed of light then turn 180 degrees and measure particle-B moving at 75% of the speed of light. Now say there is someone on particle-A and the that person particle-B is moving at 150% the speed of light but it would never be measurable to that person because they would never know that particle-B existed because the light/image of particle-B would never make it to particle-A until things slowed down enough for light to catch up.

First things first - there is no "center" of the expansion. The universe as a whole expands. Every point expands away from every other point without any center. This can be a super difficult idea to really soak up...

What made you decide to become a Physicist?

Did you have any mentors?

What advice do you have for undergrads looking to move into your field?

Know any good Chemistry REU's/Internships?

I wanted to become a physicist after learning about what a physicist actually does. Experimental physics is nothing like classroom physics. Same principles of course, but you don't spend your time calculating force vectors and sliding things down ramps. You cut metal, design parts, write code, give talks, and occasionally go to the South Pole. Sheldon Cooper is in no way like a physicist.

The number one thing to do is to get into a research lab. Find a young professor that needs energetic folks to do work in the lab. Then learn everything you can.

Congratulations! Does this more or less prove string theory? Can I now ignore the parts of my books that say we have no quantum theory of gravity?

No, it doesn't prove string theory in any direct way... I'd hang on to those sections for now :)

It does give string theorists something to hope about. The idea that we can access any information about time (and hence energy) scales so close to the Planck scale is very encouraging.

In fact, this experiment is the single largest jump to small time scales physics has ever seen. We're stuck here at ~13.71 BYr. In cosmology, we're stuck at around ~ 270,000 years (CMB). In particle physics, we can push all the way back to ~ 10^-24 seconds (or so).

But to have evidence of what happened in our universe at scales of 10^-36 seconds (or so) is absolutely astounding. It's monumental achievement to exploit the CMB (again, at ~ 270,000 yrs) to telescope to such a small timescale.

And it's only a little bit further down to get to the string scale.

It's enough to get really, really excited about- We'll keep digging :)

Does this discovery put specific bounds on inflationary theory like duration or the characteristics of the expansion? Do yo expect repeat observations to show essentially the same thing or some variation? What follow up research if any are you excited about doing now?

Absolutely! The most direct thing we can measure is the energy scale of inflation. Measuring that energy scale precisely will allow theorists to develop a real model, which will necessarily have to capture a description of the inflaton potential (the thing that drives the expansion) that matches data. Our measurement is a detection and a discovery, but by no means the final word. The process to measure this thing precisely will take years.

Hello there :)

Could this new evidence point to any other theories being true, other than the obvious?

I'd say first things first. The work to understand the inflationary universe has just begun. There are an uncountable number of physical theories in the world. The fun part is that now we get to test those theories against observations, and boot the bad ones out the door.