Einstein Was Right: Space-Time Is Smooth, Not Foamy
Space-time is smooth rather than foamy, a new study suggests, scoring a possible victory for Einstein over some quantum theorists who came after him.
In his general theory of relativity, Einstein described space-time as fundamentally smooth, warping only under the strain of energy and matter. Some quantum-theory interpretations disagree, however, viewing space-time as being composed of a froth of minute particles that constantly pop into and out of existence.
A team of researchers came to this conclusion after tracing the long journey three photons took through intergalactic space. The photons were blasted out by an intense explosion known as a gamma-ray burst about 7 billion light-years from Earth. They finally barreled into the detectors of NASA’s Fermi Gamma-ray Space Telescope in May 2009, arriving just a millisecond apart.
Their dead-heat finish strongly supports the Einsteinian view of space-time, researchers said. The wavelengths of gamma-ray burst photons are so small that they should be able to interact with the even tinier “bubbles” in the quantum theorists’ proposed space-time foam.
If this foam indeed exists, the three protons should have been knocked around a bit during their epic voyage. In such a scenario, the chances of all three reaching the Fermi telescope at virtually the same time are very low, researchers said.
So the new study is a strike against the foam’s existence as currently imagined, though not a death blow.
“If foaminess exists at all, we think it must be at a scale far smaller than the Planck length, indicating that other physics might be involved,” study leader Robert Nemiroff, of Michigan Technological University, said in a statement. (The Planck length is an almost inconceivably short distance, about one trillionth of a trillionth the diameter of a hydrogen atom.)
“There is a possibility of a statistical fluke, or that space-time foam interacts with light differently than we imagined,” added Nemiroff, who presented the results Wednesday (Jan. 9) at the 221st meeting of the American Astronomical Society in Long Beach, Calif.
If the study holds up, the implications are big, researchers said.
“If future gamma-ray bursts confirm this, we will have learned something very fundamental about our universe,” Bradley Schaefer of Louisiana State University said in statement.
100,000 Stars is a new experiment for Chrome web browsers (or any other WebGL browser like Firefox or Safari) that lets you interactively explore the Milky Way galaxy with your mouse and scroll wheel. It is gorgeous and well worth exploring.
This year marks the 50th anniversary of Britain’s first contribution to space exploration.
On 26 April 1962, its first satellite, Ariel 1, was launched by NASA, carrying experiments designed by British universities and making Britain the world’s third spacefaring nation, after Russia and America. Royal Mail is celebrating with a set of six commemorative stamps, which went on sale the 16th of October, featuring images from European Space Agency missions.
Large, dense molecular clouds are very special environments in space. Composed mainly of molecular hydrogen and helium, with small amounts of heavier gases, they are the birth place of new stars and planets.
Molecular clouds that exceed the mass of 100,000 suns are called giant molecular clouds. Giant molecular clouds are the largest inhabitants of galaxies, reaching up to 300 light years in diameter. They contain enough dense gas and dust to form hundreds of thousands of Sun-like stars. These stars are formed in the densest parts of the clouds. Molecular clouds are very cold, having temperatures ranging from about -440 to -370 degrees Fahrenheit (-263 to -223 degrees Celcius or 10 to 50 degrees Kelvin).
They usually do not radiate their own visible light and appear dark when viewed with an optical telescope. In these cold, dense environments, many atoms can combine into molecules. Giant molecular clouds can last for 10 to 100 million years before they dissipate, due to the heat and stellar winds from newly formed stars within them. An average spiral galaxy, like our own Milky Way, contains about 1,000 to 2,000 Giant Molecular Clouds in addition to numerous smaller clouds.
These exquisite images are a must see at full resolution. Space imagery from NASA’s Conceptual Image Lab. An elegant interaction powers the sun, producing the light and energy that makes life possible. That interaction is called fusion, and it naturally occurs when two atoms are heated and compressed so intensely that their nuclei merge into a new element. This process often leads to the creation of a photon, the particles of light that are released from the sun.
However, before exiting our star, each photon must first undergo a long journey. Over the course of 40,000 years it will be absorbed by other atoms and emitted repeatedly until reaching the sun’s surface. Once there, the photons stream out, illuminating Earth, the solar system and beyond. The number released from the surface every second is so vast that it is more than a billion billion times greater than the number of grains of sand on our planet.
This movie takes us on a space weather journey from the center of the sun to solar eruptions in the sun’s atmosphere all the way to the effects of that activity near Earth. The view starts in the core of the sun where atoms fuse together to create light and energy. Next we travel toward the sun’s surface, watching loops of magnetic fields rise up to break through the sun’s atmosphere, the corona.
In the corona is where we witness giant bursts of radiation and energy known as solar flares, as well as gigantic eruptions of solar material called coronal mass ejections or CMEs. The movie follows one of these CME’s toward Earth where it impacts and compresses Earth’s own protective magnetic bubble, the magnetosphere. As energy and particles from the sun funnel along magnetic field lines near Earth, they ultimately produce aurora at Earth’s poles.
How did the universe begin? The Big Bang is traditionally envisioned as the moment when an infinitely dense bundle of energy suddenly burst outward, expanding in three spatial directions and gradually cooling down as it did so. Now, a team of physicists says the Big Bang should be modeled as a phase change: the moment when an amorphous, formless universe analogous to liquid water cooled and suddenly crystallized to form four-dimensional space-time, analogous to ice.
Image:The Big Bang may have been the moment that a water-like universe froze to form the ice-like universe we see today, a new theory holds.
In the new study, lead author James Quach and colleagues at the University of Melbourne in Australia say the hypothesis can be tested by looking for defects that would have formed in the structure of space-time when the universe crystallized.
“Think of the early universe as being like a liquid,” Quach said in a statement. “Then as the universe cools, it ‘crystallises’ into the three spatial and one time dimension that we see today. Theorized this way, as the universe cools, we would expect that cracks should form, similar to the way cracks are formed when water freezes into ice.”
If they exist, these cracks should be detectable, the researchers said, because light and other particles would bend or reflect off of them as they trek across the cosmos.
The notion that space and time are emergent properties that suddenly materialized out of an amorphous state was first put forth by physicists at Canada’s Perimeter Institute in 2006. Called “quantum graphity,” the theory holds that the four-dimensional geometry of space-time discovered by Albert Einstein is not fundamental; instead, space-time is a lattice constructed of discrete space-time building blocks, just like matter looks continuous, but is actually made of building blocks called atoms.
Originally, at extremely high temperatures, the building blocks were like liquid water: they contained no structure, “representing a state with no space,” the researchers wrote in their paper. At the moment of the Big Bang, when the temperature in the universe dropped to the space-time building blocks’ “freezing point,” they crystallized to form the four-dimensional lattice we observe today.
The math describing the theory checks out, but “the challenge has been that these building blocks of space are very small, and so impossible to see directly,” Quach explained. From the human vantage point, space-time looks smooth and continuous.
However, while the building blocks themselves might be too small to detect, the physicists hope to observe the boundaries that would have formed as regions of crystallizing building blocks butted against one another at the time of the Big Bang, creating “cracks” in the universe. More work is needed to predict the average distance between the cracks — it isn’t known whether they are microscopic, or light-years apart — in order to characterize their effects on particles.
The research by Quach and his team is detailed in this month’s edition of the journal Physical Review D.
It’s official: the Sun is the most perfect natural sphere ever measured
The Earth is not round, but the Sun — contrary to long-standing scientific belief — is a different story.
To be clear: the Earth certainly isn’t flat, but it’s definitely not a perfect sphere. Technically speaking, it’s an oblate spheroid — a sphere that’s been squashed, such that the distance from Earth’s center to sea level is about 13 miles greater at the equator than at its poles. Earth isn’t really smooth, either; in actuality, it’s kind of bumpy.
Planetscape Paintings from an Interstellar Journey
“Today the art department at image and VFX design studio Framestore has shared with us some of their original illustrations of a mission into interstellar space. Here you can see what future explorers might see as they encounter a new planetary system, and survey the planets and moons there. There are some bizarre anomalies, and some places that look a lot like home.
This gallery, called “Journey,” is part of io9 and Gizmodo’s “First Comes the Dream” series, where we celebrate what inspires us to make scientific discoveries, engineer life-changing machines, and offer a new perspective on the world with science fiction. Tomorrow night, we’ll be celebrating dreams and their realization at the American Museum of Natural History in New York, where these gorgeous images will be projected on the walls of the Planetarium. We’ll be tweeting from the event, and filming a live conversation with AMNH astronomer Neil deGrasse Tyson about what inspires him.
This isn’t the last you’ll see of these images either. If they are already suggesting a story to you, that’s the idea. Starting in August, we’ll be trying out a new kind of collaborative storytelling with Framestore’s images, where you supply the story and their art department will respond by making more images to fit where our story is headed. So stay tuned for that, and keep dreaming!”
Some of the more exciting plans for the future of space exploration are currently quite literally out of reach.
The United States doesn’t have the rocket power to send men to the moon or to Mars. There are some big rockets in the pipeline that will soon restore that power to the United States, but none can match the power of Nova. Nova was NASA’s first heavy launch vehicle that never made it to the launch pad — let alone off it.