Cosmic inflation no longer theory, now a fact

 

On March 17, the most important day for cosmology in over a decade, the Harvard-Smithsonian Centre for Astrophysics made an announcement that swept physicists off their feet. Scientists published the first pieces of evidence that a popular but untested theory called cosmic inflation is right. This has significant implications for the field of cosmology.

The results also highlight a deep connection between the theories of relativity and quantum mechanics. This has been the subject of a century-old quest in physics. Cosmic inflation was first hypothesized by American physicist Alan Guth. He was trying to answer the question why distant parts of the universe were similar even though they couldn’t have shared a common history. In 1980, he proposed a radical solution. He theorized that 10^-36 seconds after the Big Bang happened, all matter and radiation was uniformly packed into a volume the size of a proton.

By the time it was 10^-33 seconds old, its volume had increased by 10⁷⁸ times — a period called the inflationary epoch. After this event, the universe was almost as big as an orange, expanding to this day but at a slower pace. While this theory was poised to resolve many cosmological issues, it was difficult to prove. To get this far, scientists from the Centre used the BICEP2 telescope.

Through the South Pole’s dry atmosphere, BICEP (Background Imaging of Cosmic Extragalactic Polarization) 2 studies the 13.5 billion-year old residual energy of the Big Bang called the cosmic microwave background (CMB). This is a field of microwave radiation that permeates the universe. The CMB consists of electric (E) and magnetic (B) fields, called modes.

The B-mode patterns, in particular, have undergone some changes as the universe aged. It is susceptible to gravitational effects. For example, the E-mode can be twisted by the strong gravitational pulls of large galaxies into the B-mode.

However, scientists were looking for effects of what are called gravitational waves. These are waves of purely gravitational energy capable of stretching or squeezing the space-time continuum.

The inflationary epoch is thought to have set off gravitational waves rippling through the continuum. In the process, they etched their effects on the B-mode, visible today as a curling pattern in the magnetic field.

To find this, a team of radio-astronomers led by John Kovac from the Harvard-Smithsonian Centre for Astrophysics used the BICEP2 telescope from 2010 to 2012. It was equipped with a lens of aperture 26 cm, scanning an effective area of two to 10 times the width of the Moon.

Then, they used the different datasets they’d collected to subtract unwanted signals from one another until they were left with one that showed only the amount of curl. Prof. Kovac said in a statement, “Detecting this signal is one of the most important goals in cosmology today.”

The curl due to gravitational waves was confirmed with a statistical significance of 5.2 sigma — sufficient to claim evidence — but only in the part of the sky they mapped. The team has set a significance of 2.7 sigma for the rest of the sky, and future work will focus on strengthening this.

Scientists were also looking for a ratio called the tensor-to-scalar ratio. It denotes the amplitude of the gravitational waves. Its value has been found to be 0.20 plus or minus 0.05. Although theoretical predictions had pegged it between 0 and 0.3, scientists had expected it to be less than 0.2. The higher value means the ancient gravitational waves were more powerful than expected, and could explain why galaxies formed so rapidly after the inflation.

Now, astrophysicists from other observatories around the world will try to replicate BICEP2’s results.

It is notable that gravitational waves are a feature of the theories of relativity, and cosmic inflation is a feature of quantum mechanics. Thus, the BICEP2 results show that the two previously exclusive theories can be combined at a fundamental level. This throws open the door for physicists to explore a unified theory of nature in new light.

NASA searches for ideas to bring asteroids closer to earth

 

U.S. space agency NASA has announced a formal proposal worth $6 million for projects that would help robots and astronauts grab an asteroid from deep space and bring it closer to earth for further study.

In support of NASA’s Asteroid Redirect Mission — a key part of the agency’s stepping stone path to send humans to Mars — agency officials are seeking proposals for studies on advanced technology development.

NASA envisages spending up to $6 million on over 25 proposals this year.

The proposal should focus on technologies that can be used to identify potential targets like sending robotic spacecraft to capture the selected asteroid and put it in a stable orbit beyond the moon.

The technology should also help astronauts get to the space rock and bring back samples in the mid-2020s, NASA said in a statement.

“We are reaching out to seek new and innovative ideas as we extend the frontier of space exploration,” said Bill Gerstenmaier, NASA’s associate administrator for human exploration and operations.

“To reach Mars, we would rely on new technologies and advanced capabilities proven through the Asteroid Initiative. We are looking forward to exciting ideas from outside NASA as well to help realise that vision,” he added.

The proposals have to be submitted before May 5 and the space agency would reward the winners around July 1 for projects that would wrap up in six months.

According to Greg Williams, NASA’s deputy associate administrator for plans and policy, the selection process would build on a workshop that generated hundreds of ideas for asteroid exploration last year.

NASA is already supporting projects such as the Asteroid Data Hunter contest, which is offering $35,000 in awards over the next six months to citizen scientists who come up with improved algorithms for identifying asteroids.

Next year, the space agency would review mission concepts for redirecting an asteroid up to 10 metres wide — or breaking off a piece of a bigger asteroid and bringing it back.

Bad weather halts MH370 search

 

Bad weather has forced the suspension of the search for debris from Malaysia Airlines flight MH370.

Heavy rain, gale force winds and low cloud made a search impracticable, said the Australian Maritime Safety Authority, which is coordinating the search in the southern Indian Ocean.

Air and searches could resume on Wednesday.

Planes from five nations trawling a Lithuania-sized patch of ocean midway between Australia and Antarctica have spotted objects they are trying to locate in the 68,500 sqkm area, 2,500 kilometres south-west of Perth.

So far none of the objects spotted has been located.

The latest sightings — “a grey or green circular object and the second an orange rectangular object” — were spotted on Monday from an Australian Orion maritime surveillance plane.

The Australian Maritime Safety Authority said in its latest statement that all of the various sightings had been in the search area.

The area was plotted using computer modelling of where the plane would have run out of fuel if, as the Malaysians now believe, it flew south after doubling back during a March 8 flight from Kuala Lumpur to Beijing.

The US Navy, which has a surface-skimming P8 Poseidon, described as the world’s most sophisticated maritime patrol aircraft, in the search fleet, is deploying a special undersea device to help find the black box of the lost Boeing 777-200.

The towed pinger locator can identify the characteristic “ping” emitted by the flight recorder from an ocean depth of more than 6,000 metres, the US Defence Department said.