50 Billion Suns! -The Biggest Single Object in the Universe

Scientists have determined the mass of the largest things that could possibly exist in our universe. New results have placed an upper limit on the current size of black holes - and at fifty billion suns it's pretty damn big. That's a hundred thousand tredagrams, and you'll never get the chance to use that word in relation to anything else.

Black holes are regions of space where matter is so dense that regular physics just breaks down. You might think physical laws are immutable - you can't get out of gravitational attraction the same way you can get out of a speeding ticket - but beyond a certain level laws which determine how matter is regulated are simply overloaded and material is crushed down into something that's less an object and more a region of altered space.

While there's theoretically no upper limit on how big a black hole can be, there are hard limits on how big they could have become by now. The universe has only existed for a finite amount of time, and even the most voracious black hole can only suck in matter at a certain rate. The bigger the black hole, the bigger the gravitational field and the faster it can pull in matter - but that same huge gravitational gradient means that the same matter can release huge amounts of radiation as it falls, blasting other matter further away.

Based on this self-regulating maximum rate, scientists at the Harvard-Smithsonian Center for Astrophysics, Massachusetts, and the European Southern Observatory, Chile, have calculated an upper limit for these mega-mammoth masses. Fifty billion suns, that's 100 000 000 000 000 000 000 000 000 000 000 000 000 000 kg, otherwise known as "ridiculously stupidly big" and triple the size of the largest observed black hole, OJ 287.

There are potential problems with this calculation. Based as it is on the radiation outflow from a black hole, new discoveries could change this estimate - though only from "insanely massive" to "ridiculously ginormous."

Scientists get death threats over Large Hadron Collider

Scientists working on the world's biggest machine are being besieged by phone calls and emails from people who fear the world will end next Wednesday, when the gigantic atom smasher starts up.

The Large Hadron Collider near Geneva, where particles will begin to circulate around its 17 mile circumference tunnel next week, will recreate energies not seen since the universe was very young, when particles smash together at near the speed of light.

	Hadron Collider: The final pieces slot into place

Such is the angst that the American Nobel prize winning physicist Frank Wilczek of the Massachusetts Institute of Technology has even had death threats, said Prof Brian Cox of Manchester University, adding: "Anyone who thinks the LHC will destroy the world is a t---."

The head of public relations, James Gillies, says he gets tearful phone calls, pleading for the £4.5 billion machine to stop.

"They phone me and say: "I am seriously worried. Please tell me that my children are safe," said Gillies.

Emails also arrive every day that beg for reassurance that the world will not end, he explained.

Others are more aggressive. "There are a number who say: "You are evil and dangerous and you are going to destroy the world."

"I find myself getting slightly angry, not because people are getting in touch but the fact they have been driven to do that by what is nonsense. What we are doing is enriching humanity, not putting it at risk."

There have also been legal attempts to halt the start up.

The remarkable outpouring of concern about turning on the experiment, the most ambitious in history, comes as a new report concludes that it poses no threat to mankind.

Since 1994, when the collider was first mooted by the multi-national European nuclear research organisation (CERN), dogged doomsayers have claimed that there would be a small but real risk that an unstoppable cataclysm would take place.

Many of the emails received by Gillies cite a gloomy book - Our Final Century?: Will the Human Race Survive the Twenty-first Century? - written by Lord Rees, astronomer royal and president of the Royal Society.

"My book has been misquoted in one or two places," Lord Rees said yesterday. "I would refer you to the up-to-date safety study."

The new report published today provides the most comprehensive evidence available to confirm that nature's own cosmic rays regularly produce more powerful particle collisions than those planned within the LHC.

The LHC Safety Assessment Group has reviewed and updated a study first completed in 2003, which dispels fears of universe-gobbling black holes and of other possibly dangerous new forms of matter, and confirms that the switch-on will be safe.

The report, 'Review of the Safety of LHC Collisions', published in the Journal of Physics G: Nuclear and Particle Physics, proves that if particle collisions at the LHC had the power to destroy the Earth, we would never have been given the chance to worry about the LHC, because regular interactions with more energetic cosmic rays would already have destroyed the Earth.

The Safety Assessment Group writes, "Nature has already conducted the equivalent of about a hundred thousand LHC experimental programmes on Earth - and the planet still exists."

The Group compares the rates of cosmic rays that bombard Earth to show that hypothetical black holes or strangelets, that have raised fears in some, will pose no threat.

As the Group writes, "Each collision of a pair of protons in the LHC will release an amount of energy comparable to that of two colliding mosquitoes, so any black hole produced would be much smaller than those known to astrophysicists." They also say that such microscopic black holes could not grow dangerously.

As for the equally hypothetical strangelets, the review uses recent experimental measurements at the Brookhaven National Laboratory's Relativistic Heavy-Ion Collider, New York, to prove that they will not be produced in the LHC.

The collider is designed to seek out new particles including the long-awaited Higgs boson responsible for making things weigh what they do, the possible source of gravity called dark matter, as well as probe the differences between matter and antimatter.

Why Disasters Are Getting Worse

In the space of two weeks, Hurricane Gustav has caused an estimated $3 billion in losses in the U.S. and killed about 110 people in the U.S. and the Caribbean, catastrophic floods in northern India have left a million people homeless, and a 6.2-magnitude earthquake has rocked China's southwest, smashing more than 400,000 homes.

If it seems like disasters are getting more common, it's because they are. But some disasters seem to be affecting us in worse ways — and not for the reasons you may think. Floods and storms have led to most of the excess damage. The number of flood and storm disasters has gone up 7.4% every year in recent decades, according to the Centre for Research on the Epidemiology of Disasters. (Between 2000 and 2007, the growth was even faster, with an average annual rate of increase of 8.4%.) Of the total 197 million people affected by disasters in 2007, 164 million were affected by floods.

It is tempting to look at the lineup of storms in the Atlantic Ocean (Hanna, Ike, Josephine) and, in the name of everything green, blame climate change for this state of affairs. But there is another inconvenient truth out there: We are getting more vulnerable to weather mostly because of where we live, not just how we live.

In recent decades, people around the world have moved en masse to big cities near water. The population of Miami-Dade County in Florida was about 150,000 in the 1930s, a decade fraught with severe hurricanes. Since then, the population of Miami-Dade County has rocketed 1,600%, to 2,400,000.

So the same-intensity hurricane today wreaks all sorts of havoc that wouldn't have occurred had human beings not migrated. (To see how your own coastal county has changed in population, check out this cool graphing tool from the National Oceanic and Atmospheric Administration.)

If climate change is having an effect on the intensities of storms, it's not obvious in the historical weather data. And whatever effect it is having is much, much smaller than the effect of development along coastlines. In fact, if you look at all storms from 1900 to 2005 and imagine today's populations on the coasts, as Roger Pielke Jr., and his colleagues did in a 2008 Natural Hazards Review paper, you would see that the worst hurricane would have actually happened in 1926.

If it happened today, the Great Miami storm would have caused from $140 billion to $157 billion in damages. (Hurricane Katrina, the costliest storm in U.S. history, caused $100 billion in losses.) "There has been no trend in the number or intensity of storms at landfall since 1900," says Pielke, a professor of environmental studies at the University of Colorado. "The storms themselves haven't changed."

What's changed is what we've put in storms' way. Crowding together in coastal cities puts us at risk on a few levels. First, it is harder for us to evacuate before a storm because of gridlock. And in much of the developing world, people don't get the kinds of early warnings that Americans get. So large migrant populations — usually living in flimsy housing — get flooded out year after year. That helps explain why Asia has repeatedly been the hardest hit area by disasters in recent years.

Secondly, even if we get everyone to safety, we still have more stuff in harm's way than ever before. So each big hurricane costs more than the big one before it, even controlling for inflation.

But the most insidious effect of building condos and industry along water is that we are systematically stripping coasts of the protection that used to cushion the blow of extreme weather. Three years after Katrina, southern Louisiana is still losing a football field's worth of wetlands every 38 minutes.

Human beings have been clearing away our best protections all over the world, says Kathleen Tierney, director of the Natural Hazards Center at the University of Colorado, Boulder. "The natural protections are diminishing — whether you're talking about mangrove forests in areas affected by the Indian Ocean tsunami, wetlands in the Gulf Coast or forests, which offer protection against landslides and mudslides."

Before we become hopelessly lost in despair, however, there is good news: we can do something about this problem. We can enact meaningful building codes and stop keeping insurance premiums artificially low in flood zones.

But first we need to understand that disasters aren't just caused by FEMA and greenhouse gases. Says Tierney: "I don't think that people have an understanding of questions they should be asking — about where they live, about design and construction, about building inspection, fire protection. These just aren't things that are on people's minds."

Increasingly, climate change is on people's minds, and that is for the better. Even if climate change has not been the primary driver of disaster losses, it is likely to cause far deadlier disasters in the future if left unchecked.

But even if greenhouse gas emissions miraculously plummet next year, we would not expect to see a big change in disaster losses. So it's important to stay focused on the real cause of the problem, says Pielke. "Talking about land-use policies in coastal Mississippi may not be the sexiest topic, but that's what's going to make the most difference on this issue," he says.