HARI SREENIVASAN: Russian commuters returned to the Moscow subway system today, after twin suicide bombings on Monday. It was a day of national mourning for the 39 people killed. Many paid their respects by leaving flowers and lighting candles at makeshift memorials.
Meanwhile, Prime Minister Vladimir Putin vowed to hunt down those behind the bombings.
VLADIMIR PUTIN, Russian Prime Minister (through translator): We know that they are keeping a low profile now, but this is a matter of honor for the law enforcement agencies to drag them out from the depths of the sewer and into the daylight. I am sure this will be done.
HARI SREENIVASAN: Russian authorities have blamed the bombings on Muslim rebels in the Caucasus region.
A ninth suspect has been arraigned in Detroit in the alleged militia plot to kill police officers. Joshua Matthew Stone was arrested last night. He's the son of the leader of the group known as Hutaree. Members of the Michigan-based Christian militia were arrested in weekend raids in three states. Court documents said they were plotting to attack police officers in a bid to spark a national uprising.
The U.S. and France renewed warnings to Iran today to stop its nuclear program. President Obama met with French President Nicolas Sarkozy at the White House. The president said the two nations are more united than ever on the need to stop Iran from gaining nuclear weapons. He said he hopes to have new sanctions in place this spring.
The world's largest atom-smasher revved up today to investigate the start of the universe, the so-called big bang theory. Subatomic particles hurtled around one another in the 17-mile ring outside Geneva, Switzerland.
We have a report narrated by Tom Clarke of independent television news.
TOM CLARKE: Some of the world's greatest minds celebrate. Nothing and no one has smashed stuff together this hard since the big bang itself. This time, the scientists have ringside seats -- on the screens in front of them, images of the subatomic wreckage created by these first high-energy particle collisions. They can now start sifting through, looking for types of exotic matter they had only dreamed of, which should shed new light on the universe.
GUIDO TONELLI, CMS spokesman (through translator): We're just at beginning. Clearly, we have to do a lot of work. We have to understand our detector, to understand physics in this new region of energy. But, if we are lucky, within a few months, we will be able to really start a major adventure in modern physics.
TOM CLARKE: It had been a nerve-wracking morning. Just weeks after it was first switched on in September 2008, the large hadron collider broke down. It took more than a year to repair and replace magnets, and, today, an agonizing few hours carried live from the control room as the machine unexpectedly shut itself off.
But, in the end, it worked a treat. Protons traveling at very near the speed of light were accelerated around the ring and then collided with pinpoint precision, right into each other. Smashups with this kind of energy should solve some of the biggest secrets of the universe, like the existence of mysterious dark matter.
HARI SREENIVASAN: The experiments will go on for at least another 18 months.
Wall Street had a relatively quiet day. The Dow Jones industrial average gained 11 points to close at 10907. The Nasdaq rose six points to close at 2410.