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Convention Countdown

The Republican National Convention is in 4 days in Cleveland.

The Democratic National Convention is in 11 days in Philadelphia.

NASA has released the first picture of Jupiter taken since the Juno spacecraft went into orbit around the planet on July 4.

The picture was taken on July 10. Juno was 2.7 million miles from Jupiter at the time. The color image shows some of the atmospheric features of the planet, including the giant red spot. You can also see three of Jupiter's moons in the picture: Io, Europa and Ganymede.

The Senate is set to approve a bill intended to change the way police and health care workers treat people struggling with opioid addictions.

My husband and I once took great pleasure in preparing meals from scratch. We made pizza dough and sauce. We baked bread. We churned ice cream.

Then we became parents.

Now there are some weeks when pre-chopped veggies and a rotisserie chicken are the only things between us and five nights of Chipotle.

Parents are busy. For some of us, figuring out how to get dinner on the table is a daily struggle. So I reached out to food experts, parents and nutritionists for help. Here is some of their (and my) best advice for making weeknight meals happen.

"O Canada," the national anthem of our neighbors up north, comes in two official versions — English and French. They share a melody, but differ in meaning.

Let the record show: neither version of those lyrics contains the phrase "all lives matter."

But at the 2016 All-Star Game, the song got an unexpected edit.

At Petco Park in San Diego, one member of the Canadian singing group The Tenors — by himself, according to the other members of the group — revised the anthem.

School's out, and a lot of parents are getting through the long summer days with extra helpings of digital devices.

How should we feel about that?

Police in Baton Rouge say they have arrested three people who stole guns with the goal of killing police officers. They are still looking for a fourth suspect in the alleged plot, NPR's Greg Allen reports.

"Police say the thefts were at a Baton Rouge pawn shop early Saturday morning," Greg says. "One person was arrested at the scene. Since then, two others have been arrested and six of the eight stolen handguns have been recovered. Police are still looking for one other man."

A 13-year-old boy is among those arrested, Greg says.

Copyright 2016 NPR. To see more, visit http://www.npr.org/.

After an international tribunal invalidated Beijing's claims to the South China Sea, Chinese authorities have declared in no uncertain terms that they will be ignoring the ruling.

The Philippines brought the case to the Permanent Court of Arbitration in The Hague, objecting to China's claims to maritime rights in the disputed waters. The tribunal agreed that China had no legal authority to claim the waters and was infringing on the sovereign rights of the Philippines.

Donald Trump is firing back at Supreme Court Justice Ruth Bader Ginsburg after she disparaged him in several media interviews. He tweeted late Tuesday that she "has embarrassed all" with her "very dumb political statements" about the candidate. Trump ended his tweet with "Her mind is shot - resign!":

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Looking For Answers Beyond The Cosmic Horizon

Sep 26, 2012

Where does the Universe end? Or, to put it differently, does the Universe have an edge? When cosmologists say that the Universe is expanding, people tend to think of an exploding bomb. They see galaxies as shrapnel, flying off in all directions. Even if intuitive, this image is dead wrong.

The cosmic expansion is an expansion of space itself. Since Einstein's theory of general relativity, space has been endowed with a plasticity that allows it to expand, shrink or fold like a rubber balloon in response to the presence of matter (and energy).

Galaxies are like islands in an ocean (in three dimensions, though), distance markers that are carried along by the expansion. Think of floating logs on a river, for example. If the galaxies have any additional motion, say, when two are near each other and attract gravitationally, this motion is superimposed on the inexorable cosmic drag. (It's actually called "peculiar motion.")

One of the consequences of the cosmic expansion is that the Universe has no center. (An assumption here, which has been confirmed so far by observations, is that the Universe, which includes all of observable space and matter in it, is homogeneous, that is, the same everywhere when averaged over large enough distances.)

Imagine that you, from your galaxy, observe other galaxies around you. Due to the expansion, most of them are moving away from you. You'd then conclude that you must be the center, since every other galaxy is receding from you. However, an observer in another galaxy will see the same thing: every one else receding from her. The same with each and every galaxy. In the Universe, space is the ultimate democracy: all points are equally important.

But if this is true, how to explain the smallness of space near the Big Bang? If the Universe is expanding, in the past distances were shorter. Astronomers can measure the recession speed of galaxies and, from them, project when they would have been "on top" of one another in a tiny volume. This moment marks the beginning of our cosmic history. According to modern measurements, this happened some 13.7 billion years ago, about three times longer than the age of the Earth. Even here, as long as we can talk about space, all points on it are equivalent.

Only when we reach the "singularity" do things break down: however, the notion that space shrinks to nothing at time zero is an extrapolation based on classical ideas and is surely wrong: new physics kicks in when the Universe is very small.

When we consider the finite cosmic history and the speed of light together, we arrive at a key concept, that of the cosmic horizon: since the speed of light delimits the speed with which we can receive information, in a Universe with a finite age we can only receive information from objects situated at the maximum distance that light could have covered within this time. Somewhat like the horizon at the beach, that delimits how far we can see.

But the ocean doesn't end at the horizon: there is more water beyond. What about the Universe? It also keeps on going. Probably. We can't be completely sure since we can't get information from beyond the horizon. And how far is that? If the Universe weren't expanding, the distance to the horizon would be 13.7 billion light-years. But since space gets stretched with the expansion, light waves get lift and we can see further than that: the cosmic horizon is roughly at 42 billion light-years away.

Beyond the horizon, the Universe could keep on going, if space is indeed infinite in all directions. It could also be closed on itself, like the surface of a balloon (but in three dimensions, not something easy to visualize), or be really weird beyond what we can see. The existence of a cosmic horizon implies a fundamental limitation to how much we can know: we are partially, if not totally, blind to what lies beyond. There could even be a multiverse out there.

To eventually find the answers to these questions will surely take a lot of ingenuity and, possibly, a new set of physical laws.


You can keep up with more of what Marcelo is thinking on Facebook and Twitter @mgleiser

Copyright 2012 National Public Radio. To see more, visit http://www.npr.org/.