when man started calculating time?

Question

If there was no time before million years how can one tell that dinosaurs lived 230 million years ago

Answer 1

Dating in geology may be relative or absolute. Relative dating is done by observing fossils and recording which fossil is younger, which is older, in accordance to its position in strata. The discovery of means for absolute dating in the early 1900s was a huge advance. The methods are all based on radioactive decay:

Certain naturally occurring elements are radioactive, and they decay, or break down, at predictable rates.

Chemists measure the half-life of such elements, i.e., the time it takes for half of the radioactive parent element to break down to the stable daughter element. Sometimes, one isotope, or naturally occurring form, of an element decays into another, more stable form of the same element.

By comparing the proportions of parent to daughter element in a rock sample, and knowing the half-life, the age can be calculated.

Scientists can use different chemicals for absolute dating:

The best-known absolute dating technique is carbon-14 dating, which archaeologists prefer to use. However, the half-life of carbon-14 is only 5730 years, so the method cannot be used for materials older than about 70,000 years.

Radiometric dating involves the use of isotope series, such as rubidium/strontium, thorium/lead, potassium/argon, argon/argon, or uranium/lead, all of which have very long half-lives, ranging from 0.7 to 48.6 billion years. Subtle differences in the relative proportions of the two isotopes can give good dates for rocks of any age.

The first radiometric dates, generated about 1920, showed that the Earth was hundreds of millions, or billions, of years old. Since then, geologists have made many tens of thousands of radiometric age determinations, and they have refined the earlier estimates. A key point is that it is no longer necessary simply to accept one chemical determination of a rock's age. Age estimates can be cross-tested by using different isotope pairs. Results from different techniques, often measured in rival labs, continually confirm each other.

Every few years, new geologic time scales are published, providing the latest dates for major time lines. Older dates may change by a few million years up and down, but younger dates are stable. For example, it has been known since the 1960s that the famous Cretaceous-Tertiary boundary, the line marking the end of the dinosaurs, was 65 million years old. Repeated recalibrations and retests, using ever more sophisticated techniques and equipment, cannot shift that date. It is accurate to within a few thousand years. With modern, extremely precise, methods, error bars are often only 1% or so.

Answer 2

remember time is relative- it's an invention mankind created for itself to put things into context. "230 million years ago" is simply a way of putting an abstract concept, what we call the passage of time, into something we can understand. Saying "a long time ago" isn't specific enough. We need to have relative dating so we know what is older than something else. We use things like carbon dating or statigraphy(sp?)-looking at layers of the earth-to "date" a specific time period when dinosaurs roamed the earth, but it's only for our own purpose and reference. We "know" that dinosaurs were around 230 million years ago because of our dating that's the context we've chosen to put it in.

Answer 3

It is done by carbon dating process, man probably calculated time since time immemorial but not as we do.

The resent past is any indication, they counted in terms of numbers of full moons.

Egyptian calender had, 365 day, there are religions very old they have 12 months and 28 or 29 days and the adjustment to Aline with season , or solar movements (Hindu calender).

Solar clock is very old.

Answer 4

The moment he went out to have his lunch off work.

Answer 5

then, what is carbon-dating for?
maybe, your question is "when did time begin?"
the answer would probably be...when man said so.

Answer 6

when somebody asked him what is the time ?