Airbrush

I like the idea of exploding a nuke next to the object, not too close to break it into pieces, but just close enough to heat up one side. This will cause outgassing (or something like that) from the object. The reaction would nudge it a little and hopefully enough. But all those ideas are useless when you don't know it exists until less than 36 hours before impact!

The Tunguska-sized object raced by Earth at 1:44pm GMT on Monday. Even if it was discovered at 1:00am GMT on Saturday, that gave us only 36 hours notice..... at the most! Merged post follows: Consecutive posts merged Even the most massive satellites in orbit would be nothing compared to even a very modest-sized NEO, which will pass through the space debris like a hot knife thru butter!

Dr.DNA quote: "What might be more viable than lasers would be a bunch of satellites in orbit, like GPS satellites, emitting radio waves or microwaves outward." That sounds good. Something like an outer space radar network of satellites. It can start with just a few satellites and then increase in number and improved coverage as money becomes available. The motion-sensing radar could make sweeps of broad areas of space. Most NEOs travel on the plane of the solar system, so that would vastly reduce the coverage needed, as compared to the GPS system.

Then the escape hatch should be a sliding door! The story at the top of this thread said that the object was discovered only 2 days before it passed by (seen on Saturday and flew by on Monday). Can coastal areas be evacuated in less than 2 days? If I had a beach house I would be skeptical about the prospects for a safe escape to high ground. Many areas have no high ground nearby. A Tunguska-sized impact in the middle of the Pacific may cause waves that are so massive that all coastal areas would be buried so deep in debris that there would be no way to exit an underground shelter. The shelter would only ensure survival from smaller impact tsunamis, but it may be your ONLY chance. For all we know, it can happen next week!

Mr. Alien, you are correct, it could take days or hours depending on the magnitude of the event. Dr DNA, you may be right, depending on how much time you have and your escape route options. Just build the thing watertight. The hatch should open INwards in case it is blocked from the outside. You should have a saw and ax, along with an assortment of tools, to cut your way out, and there should be a portal so you can see if you are still under water. On the other hand, you might get around the traffic jams on a off-road motorcycle, like the kid in Deep Impact.

Seriously, for most coastal dwellers, there would be no time to reach high ground to escape a series of waves over 100 feet high. In a standard flood you would be better off finding high ground. Impact-induced tsunamis are a different scenario entirely. Roads would quickly become massive parking lots. Your best hope would be underground in a personal shelter. Within a few hours the waters should subside so you can exit. Your house will be gone, and the shelter hatch will be covered with debris, so it will take some digging out. The entrance to the shelter should zigzag so you exit horizontally through a vertical doorway using tools you stashed inside.

We are being hit by smaller ones every day, the question is when will one big enough (at least 10% the size of Tunguska) to cause significant damage hit us? Nobody knows but it COULD happen in our life times. Maybe not as likely as I made it sound. I don't know about "enormous resources to prevent a repeat" but public opinion would force governments to devote substantial resources to the threat. The main threat from the smaller ones would be tsunamis from an ocean impact. I propose that everyone living near the ocean should have an underground tsunamic shelter. You beachfront dwellers should start digging.

"Millions of high-powered orbital telescopes"? Certainly the reason we don't is COST and economic priorities. But when a smaller one hits us somewhere, which is likely in our lifetimes, then public opinion can change 180 degrees. Not millions of orbital telescopes, but dozens for starters, and more can come on line in the future.

Motion detection is exactly how they find those things. Doing that from a network of satelites sounds like a great idea. Why don't they do that?

Not to get off topic of universe expansion and "bounce back"! But why put lightbulbs in the atmosphere? Solar panels could collect all the energy humans could need, positioned right here on Earth, IF there were not too many people on Earth, and IF there were enough solar panels. That power source will last as long as the Sun does, Billions more years, and it is totally benign environmentally, except for the process of their manufacture? Anyhow, it is fun to wonder what the universe will do over astronomical time scales and hear educated guesses.

That story means that objects that big come that close to us before we even know they exist. Last I heard is that Tunguska-sized impacts occur about once every 500 - 1,000 years. Long before that I heard they happen once every 100 years, but that must be way off. Such impacts would have been widely recorded throughout history. Anyone heard of any different frequencies?

You are not alone Klaynos, nobody gets what "anti-time" would be. Time slows down for moving objects, but it doesn't seem to reverse. Can time speed up? Does time ever stop? Time travel only occurs at Montauk Point Long Island. http://en.wikipedia.org/wiki/Montauk_project An anti-universe is possible, because anti-matter certainly exists.

They used to just call space "space". After relativity they call space "space-time" to be more precise. Be careful using the word "only" unless you really mean only. We don't know what else connects time and space. For now, the speed of light does just fine.

I will try to be more precise in my use of terminology. I dabble only very casually in cosmology. It all started when I saw Carl Sagan's "Cosmos" series long ago. More recently the History Channel's "The Universe".

The story above did not say exactly when this asteroid was first discovered. It sounded like it was first discovered last Saturday. How often do objects that large appear catching us by surprize only a couple days before closest encounter? "No rock of any significant size" means what size? If the world was going to end in a year from now, would it be possible to supress that knowledge from the general public? It would result in total anarchy and social break down.

It would be more precise to say space and time are linked by the speed of light ABSOLUTELY, not just abstractly and mathematically.

I did just like you said Martin, and I now believe we will probably never find any galaxy or quasar with a red shift greater than 8, because before 13 Billion years ago was the Dark Ages. They also said that galaxies formed even before quasars.

"...any possibility of there [being] anti-time[?]" Sure, anything is possible, just not probable. There is time dilation. In the most far-out episodes of The Universe on the History Channel, they never mentioned "anti-time". Nothing about anti-time on wikipedia, and they even mention time travel. The concept "arrow of time" implies time is positive. Has anyone heard of "anti-time" in scifi? Not once did I ever hear Mr. Spock mention anti-time in any episode of Star Trek. They just travel faster than light and go back in time.

z= 7.6 means something is now 30 billion lightyears away. z= 1090 means something is now 46 billion lightyears away. Interesting comparison! Does that mean that the current "edge" of the visible universe (the region of CMB) is about 50% further away than the furthest known galaxy that can be seen? Does that mean we probably will not see any galaxies with redshifts greater than 8, simply because the age of the universe would not allow it? Even using the greatest gravitational magnifier known Abell 1689?

By "open universe" I had always supposed that it meant the universe would never stop expanding and eventually become either a Big Rip or it would expand to a point and stop, but never contract. "Closed universe" meant that gravity would win out in the end and expansion would slow down, stop, and begin contracting into a Big Crunch. Other terms used were bounded or unbounded, finite or infinite, and flat or curved. I am confused about how all these qualities interact. What's your best guess?

Nice explanation Martin. I would add that currently cosmologists believe in an open universe, and the expansion will only accelerate due to dark energy and never bounce-back whatever "bounce-back" means. The next Dark Age will begin after the red dwarf stars slowly burn out over the next Trillions of years. Then there will be only cold dead stars and black holes. The last supermassive black holes will evaporate over Googles of years. Unless something interesting happens during those vast time spans, like another Big Bang or something.

Hopefully the next Tunguska-sized event will happen somewhere safe, but most likely it will hit an ocean and the Tsunamis could be devastating. What is more likely is a smaller one, hopefully it will be just big enough to wake us up to the reality of those objects. Then I dread our poor economic situation because the new imperative will be to defend against those objects, which will cost a LOT.

I found a 2-12-08 story with a name for that very early galaxy, A1689-zD1, that is magnified ten times by the gravitational lensing of Abell 1689. http://www.nasa.gov/centers/jpl/news/Spitzer20080212.html The light originated from A1689-zD1 about 700 Million years after the Big Bang and is now about 12.8 Billion years old. It is among the first galaxies to form after the Dark Ages, which lasted from about 400,000 years until about one Billion years after the Big Bang. I didn't see any redshift number, but it must be the one Martin introduced here with a redshift of ~7.6 and the galaxy is now almost 30 Billion LY from us. How much further is the CMB if it has a redshift of 1090, which is 136 times higher redshifted than z = 8?

Interesting news Martin. From reading the article I am only able to gather that it has a redshift (z) of ~7.6, plus or minus 0.4. Does it say how old the light is? Anyone want to venture an estimate of its' current distance from us? Why don't they give these astonishing objects on the edge of our visual horizon names? What is the highest redshift possible for an object to still be visible?

OK, sorry to be so critical. In the hypothetical sense, she would need to send a balloon up into the stratosphere with a device that will open a trap at a certain height, and stay open long enough for the sample, then close tightly. Then it should release enough helium after the sample trap shuts so it will come down gently. You may need to retreive it from the middle of an ocean, or in very remote wilderness, or in the middle of a foreign country, all depending upon many variables. It should have a GPS tracking device so you can travel half-way around the world to retrieve it. And don't forget to have a sign on it (in every conceivable language) for a substantial reward for its' safe recovery. A better way is hire a plane that can take the device, attached to the outside of the plane, that high. That will solve the problems encountered with a balloon. Wiki gave stratosphere heights starting at 10 km (6 miles or over 32,000 feet) and up to 50 km (31 miles or ~164,000 feet).