What was the background radiation level 165 million years ago?
608949
cant answer secifically, but you should be able to back calculte taking elements present today and using the half lives as your main variable.
890008
Radiocarbon dating relies on a simple natural phenomenon. As the Earth's upper atmosphere is bombarded by cosmic radiation, atmospheric nitrogen is broken down into an unstable isotope of carbon - carbon 14 (C-14).
175894
The bible is wrong. It was written by people who didn't know the science.\n\nMost fossils are NOT dated using carbon dating. Why not? Because it is useless for ages more than about 100,000 years. Most fossils are much, much older than that. Usually either potassium-argon, rubidium-strontium, or uranium series dating is used. These don't have the difficulties associated with carbon dating and are self-correcting in the sense that they will let you know if a sample is contaminated.\n\nThe earth is about 5 *billion* years old, which is much older than 40 million, which is much more than 12,000.
561786
the human rase is much older than that. civilization is 6000 years old
181131
The earth as it was 100 million years ago.\n\nSimple really!
993258
The Earth was formed around 4.57 billion (4.57×109)[1] years ago
436472
3000 years counting from when?
1024575
Radiocarcon dating is used.\nRadiocarbon dating is a radiometric dating method that uses the naturally occurring isotope carbon-14 to determine the age of carbonaceous materials up to ca 60,000 years. Within archaeology it is considered an absolute dating technique. The technique was discovered by Willard Frank Libby and his colleagues in 1949 during his tenure as a professor at the University of Chicago. In 1960, Libby was awarded the Nobel Prize in chemistry for his method to use carbon-14 for age determination.\nCarbon has two stable, nonradioactive isotopes: carbon-12 (12C), and carbon-13 (13C). In addition, there are tiny amounts of the unstable isotope carbon-14 (14C) on Earth. Carbon-14 has a half-life of 5730 years and would have long ago vanished from Earth were it not for the unremitting cosmic ray impacts on nitrogen in the Earth's atmosphere, which forms more of the isotope. When cosmic rays enter the atmosphere, they undergo various transformations, including the production of neutrons. The resulting neutrons participate in the following reaction on one of the N atoms being knocked out of a Nitrogen (N2) molecule in the atmosphere:\n\n1n + 14N → 14C + 1p \n \nAtmospheric 14C, New Zealand[1] and Austria[2]. The New Zealand curve is representative for the Southern Hemisphere, the Austrian curve is representative for the Northern Hemisphere. Atmospheric nuclear weapon tests almost doubled the concentration of 14C in the Northern Hemisphere [3].The highest rate of carbon-14 production takes place at altitudes of 9 to 15 km (30,000 to 50,000 ft), and at high geomagnetic latitudes, but the carbon-14 spreads evenly throughout the atmosphere and reacts with oxygen to form carbon dioxide. Carbon dioxide also permeates the oceans, dissolving in the water. For approximate analysis it is assumed that the cosmic ray flux is constant over long periods of time; thus carbon-14 could be assumed to be continuously produced at a constant rate and therefore that the proportion of radioactive to non-radioactive carbon throughout the Earth's atmosphere and surface oceans is constant: ca. 1 part per trillion (600 billion atoms/mole). For more accurate work, the temporal variation of the cosmic ray flux can be compensated for with calibration curves. If these curves are used, their accuracy and shape will be the limiting factors in the determination of the radiocarbon age range of a given sample.\n\nPlants take up atmospheric carbon dioxide by photosynthesis, and are eaten by animals, so every living thing is constantly exchanging carbon-14 with its environment as long as it lives. Once it dies, however, this exchange stops, and the amount of carbon-14 gradually decreases through radioactive decay.\n\n14C → 14N + 0β \nBy emitting a β particle(Beta decay), carbon-14 is changed into stable (non-radioactive) nitrogen-14. This decay can be used to get a measure of how long ago a piece of once-living material died. However, aquatic plants obtain some of their carbon from dissolved carbonates which are likely to be very old, and thus deficient in the carbon-14 isotope, so the method is less reliable for such materials as well as for samples derived from animals with such plants in their food chain.
396602
4.5 billion years old maybe http://www.talkorigins.org/faqs/faq-age-of-earth.html
937907
Approximately 5,000,000,000 years
921793
background radiation is naturally occuring radioactive elements that exist in nature.\n\nWhy is it present... good grief that's a good question. God, this is where you would step in with an explanation lol
1076419
The sun is only about 4.5 billion years old.  The cloud of gas and dust that it formed out of was probably huge, though.
188493
MEZOZOIC, CRETACEOUS AND JURASSIC PERIOD (FROM 125 MILLION YEARS AGO TO 65 MILLION YEARS AGO
892212
Around 4 billion years old.
434019
Global.\nThere is TONS of physical evidence for a world-wide flood that happened about 4400 years ago - Just like the Bible says.\nThere are several places to get more information about this, but the best website I know of is http://www.drdino.com
619711
The earth (and its chemical reactions) wasn't born until about 8 billion years after the Big Bang ... things had slowed down a bit by then.
653069
The Earth is 4,570,000,000 years old, approximately; though many Creationists think it to be only 6000 "without proof otherwise" they are wrong: we have proven it using gravitational measurements of other planets, measurements of solar brightness over time, radioactive dating, continental drift, and many other factors. If you want to  force religion on people, don't do it in a SCIENCE forum! You will only cause heated debates and great offense from both sides.