Airbrush

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).

Well Mr. Alien, I can go along with the hypothetical thing. You probably know a lot more about this stuff than I do. But I beat you with common sense. She posted that a week ago and never returned, and obviously doesn't take it seriously. She is probably in high school.

One more thing, what does her question have to do with Astronomy and Cosmology? Her post should have been moved to a relevant discussion area.

I don't see anything practical about what she is trying to do. She will most likely just get into trouble or waste a lot of time and money. How about studying something more accessible? Nobody asked Christiana what her educational level is or what her credentials are. Let's get some context before encouraging her. That was her first post here, and we don't know anything about why she wants to do something so difficult. Hey Christiana, how old are you? What experience do you have?

Thanks for your help NowThat. The math I had trouble with was exactly your illustration and I remember discussing exactly this with you on Historychannel.com. I finally figured out where you got 29.7 Gly. Gly is new terminology to me. "Gly" must mean giga light years. So, for us newbies, when reading about objects that are on the edge of our visual horizon, about redshifts of 6.5 or higher, a good rule of thumb is take the time the light left in the past and multiply it by 2.3. 13 billion years ago X 2.3 = 30 Billion light years away NOW (approx). That discovery is over 4 years old, so I believe we may not ever find anything much further away than that. Right?

I am designing a spaceship to take a few friends with me to Mars, can someone help me out please? Leave it to NASA, the pros and the corporations. Because of all the difficulties listed above, try something easy instead.

The 2004 story (see below) reported a gravitationally lensed galaxy, behind a cluster called Abell 2218, that has a record-breaking redshift of 7.0. “We are confident it is the most distant known object,” California Institute of Technology astronomer Richard Ellis said of the galaxy, which lies roughly 13 billion light-years from Earth. Put another way, the light traveled for 13 billion years to reach Earth." The error in his report states it IS roughly 13 Billion LY from Earth, but it is really light that left it about 13 Billion years AGO. It is much further away now. Is there a general rule-of-thumb for converting 13 Billion years AGO to a current distance from Earth? Could we just double 13 Billion and call it about 26 Billion LY away, since it must be receding at nearly light speed? I have seen formulas for computing current distances, but the math is beyond me. http://www.msnbc.msn.com/id/4274187/

The ether, which is an intuitive construct, may just be too subtle to be detected, like the program for existence. I like that stuff about geometry existing without being the geometry of anything. Maybe Geometry is what people really mean by "God" (without knowing it).

I was trying to visualize the most massive known object in the universe, OJ-287, the 18 Billion solar mass supermassive blackhole (in binary with a 100 Million solar mass SBH) which has an accretion disk with a diameter of 0.19 light weeks. If superimposed over our solar system, with the singularity at the center of our sun, the event horizon would extend to within the orbit of Mercury by 3 million miles, at a radius of 33 Million miles, and the outer edge of the accretion disk would extend only one tenth the distance to the Oort cloud, which is at 50,000 au. Out to what radius would the "ring zone" of the energetic reaction extend? How thick would the ring be? What would be the diameter of the ring of energetic reaction?

Just because matter has anti-matter, does not mean that time has anti-time. Time is an artificial measuring device like length. Using this logic there cannot be anti-time just like there cannot be anti-length. Distance measures are always positive.

Thanks for your help Martin. I just discovered info about OJ-287. I assume the supermassive black holes (SBH), that are probably at the center of quasars, are on the order of Billions of solar masses. We already know that the extreme yet compact brightness of a quasar is not from the relativistic jets. If we were looking down a polar jet, then what we are looking at is called a blazar. But most quasars are not blazars, right? So the extreme brightness of a quasar does not come from the jets, but must be the result of massive amounts of gas and dust that are streaming into the SBH on the inner edge of the accretion disc. I just discovered this article (below) about a binary SBH system, which is called OJ-287 over 3 Billion LY away, with a central black hole of 18 Billion solar masses (the largest known). It has a smaller SBH of "only" 100 Million solar masses in a 12-year orbit around it. They estimated the outer edge of the accretion disk of the bigger one as only about 10 light weeks in diameter. Ten light weeks is about 0.19 light years, or over 1.1 Trillion miles if my math is correct (60 x 60 x 24 x 70days x 186,000mi/sec = 1.116 Trillion miles). Next I need to calculate the diameter of the event horizon for OJ-287. Using the data that Martin got from wikipedia, the Schwarzenegger (snicker, snicker, ok...."Schwarzschild") radius of an 18-Billion-solar-mass black hole is about 54 Billion meters or 54 Million kilometers or 33.5 Million miles, or about a third the distance from the earth to the sun. Now I need some time to groke this in fullness. http://www.caha.es/18-billions-of-suns-support-einstein.html