Friday, March 28, 2014

152.7 - And Another Thing: ripples in spacetime

And Another Thing: ripples in spacetime

So we'll finish up this week with an edition of And Another Thing. This is where we talk about stuff that's not political; usually it's some cool science stuff.

I was going to do this last week but I didn't have enough time so I'm doing it now even though the news is a couple of weeks old because it is just too cool to let pass.

You've undoubtedly heard about this big breakthrough, about seeing "the beginning of time." You may have been unclear as to what it means. I read several articles and some were written by scientists, very familiar with the territory, who because they were so familiar with it wrote way too far over the heads of most people. Other articles seemed - well, I'm sure you've had the experience of reading something someone wrote and you can just tell that while they can say the words they don't have a real understanding of the topic. So the coverage was either too complex or too basic.

I hope to come somewhere in between.

There is a scientific theory about how the universe began. Understand, a scientific theory is not a guess, it's not an opinion, it's not just someone's idea, it's something that explains different phenomena and has been confirmed by observation, including observations that it predicted in advance would be made.

This theory about how the universe began became known as the Big Bang.

There were problems with the original Big Bang theory, things it struggled to explain. What those issues were isn't relevant here, what's important is that they were there.

In 1979, an astrophysicist named Alan Guth proposed the Inflationary Universe model of the Big Bang, which served to address those problems. The original idea of the Big Bang was that the universe at one point was incredibly dense and hot and expanded outward from there. The Inflationary model proposed that in the first incredibly short fraction of a fraction of a fraction of a second of the universe, it expanded incredibly rapidly, then slowed down to a more moderate rate of expansion such as we see now.

The Big Bang theory got its biggest confirmation in the early 1990 by the COBE satellite, COBE standing for COsmic Background Explorer, and an image produced from the data gathered is the one you see here.

The image is of space, not Earth. And the variations in color are a graphic representation of tiny variations in the temperature, in the energy, that is coming at us from all directions, that energy being the cosmic microwave background. You could, if you wanted, liken it to a constant hiss everywhere in the universe (except, of course, it doesn't actually make a noise).

The point here is that this background "noise" filling the universe was a precise prediction of the Big Bang theory, down to the level of the energy detected. Which means the Big Bang fulfilled one of the base requirements of a valid theory: It predicted the results of future observations.

The COBE image was later supplanted by a more detailed image from data obtained by the Wilkerson Microwave Anisotropy Probe, or WMAP.

Here, however, is where an issue arises. These images graphically display tiny fluctuations in cosmic microwave background from a point in time about 380,000 years after the Big Bang. They are - again, you could think of it this way - kind of like the afterglow of the Big Bang.

We cannot see further back in time. This is not a technical constraint; if the theories are right, it's a physical constraint.

So when they say that scientists have seen "the beginning of time," that's not technically accurate.

But what we can do is consider our theories about the Big Bang, consider what is predicted, and examine the data we have about the cosmic microwave background, that is, to take what we know and what we predict in order to make further observations looking for evidence about the beginning of time, to look for the telltale signs of those first instants.

That's what the scientists involved did. And the image shows what they found.

Doesn't look like much does it? No, it doesn't. But those lines indicate or more accurately represent changes in light.

See, one of common predictions of Einstein's General Theory of Relativity is that gravity bends light. This has been proved multiple times; in fact, it's so well-established that astronomers use it as a tool. According to theory, the Big Bang should have produced gravitational waves that would polarize light, gravitational waves rippling through the universe like ripples on a pond.

That's what those lines represent: the polarization of light under the influence of gravity.

So this is actually what they found: They found ripples in spacetime, ripples imposed on the infant universe by gravitational waves.

Ripples in spacetime dating from roughly a trillionth of a trillionth of a trillionth of a second after the Big Bang.

Ripples in spacetime that are a "smoking gun" for inflation.

Ripples in spacetime that offer insight into fundamental physics, including the idea that the four fundamental forces of the universe - electromagnetism, gravity, and the weak and strong nuclear forces - were all united as a single force at the Big Bang.

Ripples in spacetime that by showing the existence of gravitational waves provide proof for the last, great, untested prediction of Einstein's General Theory of Relativity, which was those very gravitational waves.

Ripples in spacetime, that is, that provide backing for three separate scientific theories all related to the fundamental nature of the universe.

And ripples in spacetime that represent the first real data we have - not conjecture, not hypotheses, not mathematical calculations, but actual data - about the first trillionth of a trillionth of a trillionth of a second in the history of the universe.

And if you don't think that's cool, there is no hope for you.


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