Ripples in Space Are Evidence of Universe's Early Growth Spurt

When the universe expanded tremendously after the Big Bang, the resulting gravity waves interacted with the cosmic microwave background to produce this characteristic “B-mode” pattern. Credit: BICEP2 Collaboration

Big news in the cosmos today! Researchers from the BICEP2 south pole telescope have found ancient proof that the universe expanded tremendously after the Big Bang, a theory known as inflation. The discovery tells us (albeit indirectly) about an even earlier stage of the universe than we’ve ever before observed, and it provides crucial evidence that inflation did indeed occur. In so doing, it extends our model of the early universe from about one second after the Big Bang right back to less than 10-37 seconds after the event — a stunning leap forward (or backward, as the case may be).

To understand this, let’s back up 13.8 billion years or so, to the Big Bang. Also known as the birth of the cosmos and the origins of time and space, this burst of everything set the universe in motion. But a few niggling issues cast some doubts on the Big Bang theory — one of which was the mystery of how the universe came to be so uniformly spread out.

Enter the idea of inflation, in 1980, which suggested that just a few instants after the big moment, the universe suddenly grew enormously. This addition to the cosmic timeline explained why the universe was relatively uniform and it fit nicely with what we already knew about the universe’s earliest moments. However, cosmologists had no direct proof of inflation.

One way to prove inflation occurred, physicists thought, would be to look for gravitational waves created in its wake. These are basically ripples in the “fabric” of space-time — what the universe is made out of. Gravity is a relatively weak force, though, so we could only hope to detect the largest waves out there, caused by huge interactions like black holes colliding. Even though inflation was a relatively huge thing — it literally shaped the whole universe — the gravity waves it produced are now too weak to measure directly.

So instead, researchers were looking for the effect of inflation’s gravity waves on light. And not just any light, but the cosmic microwave background, “echoes” of light leftover from the Big Bang’s energy, created when the universe was just 380,000 years old. When this light interacted with the gravity waves, the theories said, it would have produced a distinctive pattern, called the B mode, in the light’s polarization. Such a pattern would be direct evidence that the gravity waves caused by inflation were real, and thus a key proof of inflation. And today, scientists announced they’d found it.

Assuming the finding is confirmed (and that looks likely — the team apparently spent 3 years going over their own data to make sure it was sound before coming forward with it), that’s huge news for cosmology. Direct evidence for inflation has been sought after for decades. Nature quotes Alan Guth, the main “inventor” of inflation, as saying, “This is a totally new, independent piece of cosmological evidence that the inflationary picture fits together,” and adding that the findings are “definitely” Nobel prize-worthy.

But it’s also big news for a couple of other reasons. First, in addition to being the first evidence for inflation, it’s also the first direct evidence for gravitational waves. Even though some observatories have been (and will continue!) looking for these gravitational waves, they’re still incredibly hard to find. The more data we have on these weird, space-time warping ripples, the more we’ll be able to understand the universe itself, and this is a great step in that direction. 

And the other bit of significance to this has to do with understanding gravity in the first place. It’s currently the only one of the four fundamental forces not to play nice with quantum mechanics, which explains how things work on the tiniest scales. At high temperatures (like those found shortly after the Big Bang), the other three even begin to unify into a single super-force. One of the biggest issues in physics today is figuring out how (or if) gravity fits into this picture, and the findings that gravitational waves can result from inflation, a fundamentally quantum phenomenon, suggests that quantum gravity might indeed be possible.

A glimpse into the very first milliseconds of our universe, plus bigger questions ahead — all in all, it’s a pretty good day for science.

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WRAPUP 2-IMF trims global growth forecast, sees bumpy recovery

* IMF sees world growth of 3.3 pct in 2013, down two-tenths

* IMF warns against fatigue in battling European debt crisis

* Japan economy to expand with new monetary steps

* Fund estimates first Fed rate increase in 2016

* Emerging economies picking up steam again

By Lesley Wroughton

WASHINGTON, April 16 (Reuters) - The International Monetary Fund on Tuesday trimmed projections for global economic growth for this year and next to take into account sharp government spending cuts in the United States and the latest struggles of recession-stricken Europe.

While it said economic prospects had improved in recent months with a fading of financial risks, it warned Europe against relaxing efforts to combat its debt crisis given the messy bailout in Cyprus and a political stalemate in Italy.

The IMF raised its forecast for Japan, welcoming the Bank of Japan's aggressive new monetary stimulus, which it said would boost growth and help vanquish deflation.

"While some tail risks have decreased it is not time for policymakers to relax," IMF chief economist Olivier Blanchard told a news conference to discuss the World Economic Outlook.

The report was released as global financial leaders gathered for the semiannual meetings of the IMF and World Bank later this week.

The IMF cut its 2013 forecast for global growth to 3.3 percent, down from its January projection of 3.5 percent. It also trimmed its 2014 forecast to 4.0 percent from 4.1 percent.

A more subdued outlook for the United States and for the euro zone led it to lower its growth forecast for advanced economies to 1.2 percent for 2013 while it kept its 2014 forecast at 2.2 percent.

While it lowered its projections for growth in emerging economies to 5.3 percent for this year, it also said growth was already accelerating and would hit 5.7 percent in 2014. Growth has returned to a healthy pace in China and activity is expected to recover in Brazil next year, the IMF said.

Strong domestic demand in sub-Saharan Africa should help boost growth in both resource-rich and poorer economies in that region, the Fund added. Meanwhile, growth in the Middle East and North Africa is likely to dip this year as oil production slows in some oil-exporting nations and "Arab Spring" countries struggle with political transitions.

"Notwithstanding old dangers and new turbulence, the near-term risk picture has improved as recent policy actions in Europe and the United States have addressed some of the gravest short-term risks," the Fund said.

BOJ ON TRACK BUT NEEDS HELP

Blanchard said the dramatic overhaul of monetary policy announced by the Bank of Japan was a necessary step and he hoped it would succeed.

The IMF said inflation in Japan would likely rise above zero in 2013 and temporarily jump in 2014 and 2015 in response to an increase in consumption taxes.

The Bank of Japan unleashed an intense burst of monetary stimulus earlier this month, pledging to inject about $1.4 trillion into the economy in less than two years, a major shift from its previous incremental steps.

Tokyo came under fire before a meeting of officials from the Group of 20 leading economies in February for comments that suggested it was targeting specific levels for the yen with its easing of monetary and fiscal policy. The yen last week hit a four-year low against the dollar.

But the IMF said it found "no large deviations of the major currencies from medium-term fundamentals" and dismissed talk of a "currency war" as overblown.

"We think it is a logical consequence of appropriate monetary policy," Blanchard said when asked about the yen's sharp decline.

The Fund said the U.S. dollar and euro "appear moderately overvalued" and the Chinese renminbi "moderately undervalued." Evidence on the value of the yen "is mixed," it added.

FIRST FED RATE INCREASE IN 2016

The IMF said Europe and the United States had dodged bullets by enacting policies that laid to rest the notion of a euro zone breakup and the possibility the world's richest economy would fall off a "fiscal cliff" of tax increases and budget cuts.

However, it suggested an easier monetary policy might be warranted in the euro zone.

"Given moderating inflation pressure, monetary policy should remain very accommodative. Room is still available for further conventional easing, as inflation is projected to fall below the European Central Bank's target in the medium term," it said.

The IMF forecast economic contractions in France, Spain and Italy this year. IMF economist Jorg Decressin said Italy's economic policy was on the right track and prospects would brighten next year with less need for government spending cuts. He also said fiscal policy in France is "appropriate" even if the country misses the goal to trim the deficit below an EU ceiling of 3 percent of GDP in 2013.

The Fund also made clear that, while a worst-case outcome had been avoided, fiscal policy in Washington had tightened more than it had expected - a key reason for its forecast downgrade.

It said across-the-board spending cuts known as the "sequester" would shave about 0.3 percentage points from gross domestic product this year, the IMF said. If the sequester continued into the next fiscal year, it could trim another 0.2 percentage points from GDP growth, the IMF added.

Blanchard said without fiscal consolidation, U.S. economic growth would probably be between 1.5 percent to 2 percent higher this year.

As for U.S. monetary policy, the IMF said it expects the Federal Reserve to hold interest rates near zero into early 2016, although it cautioned that the Fed may need to tighten policy earlier "should upside risks to growth materialize."

The Fed last month maintained a controversial program of buying $85 billion of bonds a month, while pledging to keep interest rates near zero at least until unemployment falls to 6.5 percent, so long as inflation stays under 2.5 percent.

The Fund said developing a comprehensive medium-term deficit reduction framework that reformed so-called entitlement programs and raised additional revenues should be the top priority for the United States.

"Such a comprehensive plan should place fiscal consolidation on a gradual path in the short term, in light of the fragile recovery and limited room for monetary policy," the IMF added.

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Rigid growth matrix: A key to success of cardiac tissue engineering

A new study by researchers at UCLA suggests that the elasticity of the physical matrix used for growing heart muscle cells outside of the body may be critical to the success of cardiac tissue engineering. The results were published in the journal Science and Technology of Advanced Materials this week.

Adult heart muscle is the least regenerative of human tissues. But embryonic cardiomyocytes (cardiac muscle cells) can multiply, with embryonic stem cells providing an endless reservoir for new cardiac tissue. A new study by Nakano, Gimzewski and their co-workers at the University of California, Los Angeles (UCLA) suggests that the elasticity of the physical matrix used for growing cardiomyocytes outside of the body may be critical to the success of cardiac tissue engineering efforts.

Published in the journal Science and Technology of Advanced Materials, the study found that a stiff or rigid environment not only enhances the function of existing cardiomyocytes (as has previously been shown), but also promotes the generation of cardiomyocytes from embryonic stem (ES) cells. It may therefor be possible to grow new heart muscle tissue from stem cells by manipulating the stiffness of the medium they're grown in.

In living organisms, a type of adult stem cells called mesenchymal stem cells (MSCs) are extremely sensitive to the elasticity of different materials, when cultured outside the body. For example, soft growing matrices that mimic brain tissue promote the differentiation of MSCs into neurons, while rigid matrices that resemble bone tissue promote the differentiation of MSCs into bone cells.

In this study, the UCLA team examined the role of matrix elasticity on cardiac muscle development using mouse and human embryonic stem cells, which were grown on different substrates of a silicon-based organic polymer that varied in stiffness. The team found that rigid matrices promoted the generation of more cardiomyocytes cells from ES cells. In addition, ES-derived cardiomyocytes displayed functional maturity and synchronization of beating when cultured with cardiomyocytes harvested from a developing embryo.

The team recommends further research on how biophysical cues determine the fate of embryonic stem cells in order to improve cardiac tissue culture methods for regenerative medicine purposes.

More information: Arshi, A. et al. Rigid microenvironments promote cardiac differentiation of mouse and human embryonic stem cells, Science and Technology of Advanced Materials 14 (2013) 025003. doi:10.1088/1468-6996/14/2/025003

Journal reference: Science and Technology of Advanced Materials

Provided by National Institute for Materials Science

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