10 Methods Scientists Use to Date Things | Mental Floss
Goffman's work on self-presentation explicates the ways in which an individual may Some theorists argue that CMC gives participants more freedom to explore A research study found that over a quarter of online dating Online users look to small cues in order to develop impressions of others. similar native semantics, but this technique should only be used as part of a well- The current WAI-ARIA specification has a long history dating back to two former of the Web Accessibility Initiative to create a single specification called. There are 4 predictable stages that couples experience in a dating relationship. with their partner while finding ways to keep from “pushing” for commitment.
Chemical Warfare A pile of skeletons probably wouldn't tell us much more than the obvious. But University of Leicester archaeologist Simon James sees evidence that, to him, dates the first known chemical warfare attack back to A. In that year, Persians attacked a Roman garrison at Dura-Europos in Syria; when they tried to mine under the walls, Romans tried to counter by mining under the Persian tunnels.
Archaeologists found the pile of Roman bodies in one of the tunnels, but no cause of death. James thinks it was asphyxiation. In the tunnels, he says, there was bitumen and sulfur—materials that, when burned, give off toxic gas. So, he says, the Persians probably used chemical warfare to do in their rivals. The Magnetic Fields One classical way to date objects is to take note of what strata of rock they occupy—rocks come in layers, with the oldest at the bottom. But those rocks also carry less obvious information—their magnetic signatures.
The Earth's magnetic field varies all the time, by both strength and orientation. At the time rocks form, however, their magnetic materials acquire the particular orientation of the planet's magnetism at the time, giving geologists a window into the Earth's magnetic past. Ice Cores You've probably heard about ice cores, but what are they exactly? Ice sheets are laid down in layers, and the layer corresponding to each year is a little different.
The important thing for climate researchers is that the oxygen isotopes present in a layer can help show what the temperature was that year. So by extracting a cylindrical core sample containing layers that go way back, they can build a model of the climate of the past. Pollen Finally, pollen is good for something besides making you sneeze.
Deposits of pollen deep in the ground can reveal what the vegetation was like at that time, and ergo, what the area's climate might have been like. Radiocarbon dating has become the standard method to date organic material, making pollen deposits sort of useless in that regard. But pollen can still help scientists interpret the environment of the past. Volcanic Ash Everything, it seems, has a fingerprint, and volcanoes are no exception—each eruption contains a chemical mix that is all its own.
So if you knew the specific signature of say, the 79 A.
- Chronology: Tools and Methods for Dating Historical and Ancient Deposits, Inclusions, and Remains
- Dating in Europe: First date etiquette
Thus, any objects in that "tephra," the name for solids ejected during a single eruption, date to that era of Roman history, and anything below it would be older. This dating system is called tephrochronology. Thermoluminescence You probably know that radiation you can't see is flying all around you, but you might not know that not only do objects absorb that radiation, they also let their trapped radiation go when heated up. Knowing this, an archaeologist could heat up an object, watch how much radiation is released and determine how old the thing might be.
It's particularly useful for ceramics. When a potter in Ancient Greece fired his kiln and baked a pot, that released the clay's stored electrons and reset the clock to zero.
Prediction This step involves determining the logical consequences of the hypothesis. One or more predictions are then selected for further testing.
Dating in Europe: First date etiquette | Expatica
The more unlikely that a prediction would be correct simply by coincidence, then the more convincing it would be if the prediction were fulfilled; evidence is also stronger if the answer to the prediction is not already known, due to the effects of hindsight bias see also postdiction. Ideally, the prediction must also distinguish the hypothesis from likely alternatives; if two hypotheses make the same prediction, observing the prediction to be correct is not evidence for either one over the other.
These statements about the relative strength of evidence can be mathematically derived using Bayes' Theorem. Scientists and other people test hypotheses by conducting experiments. The purpose of an experiment is to determine whether observations of the real world agree with or conflict with the predictions derived from a hypothesis.
If they agree, confidence in the hypothesis increases; otherwise, it decreases. Agreement does not assure that the hypothesis is true; future experiments may reveal problems. Karl Popper advised scientists to try to falsify hypotheses, i. Large numbers of successful confirmations are not convincing if they arise from experiments that avoid risk. For example, tests of medical treatments are commonly run as double-blind tests. Test personnel, who might unwittingly reveal to test subjects which samples are the desired test drugs and which are placebosare kept ignorant of which are which.
Such hints can bias the responses of the test subjects. Furthermore, failure of an experiment does not necessarily mean the hypothesis is false.
Experiments always depend on several hypotheses, e. See the Duhem—Quine thesis. Experiments can be conducted in a college lab, on a kitchen table, at CERN's Large Hadron Colliderat the bottom of an ocean, on Mars using one of the working roversand so on. Astronomers do experiments, searching for planets around distant stars.
Finally, most individual experiments address highly specific topics for reasons of practicality. As a result, evidence about broader topics is usually accumulated gradually. Analysis This involves determining what the results of the experiment show and deciding on the next actions to take. The predictions of the hypothesis are compared to those of the null hypothesis, to determine which is better able to explain the data.
In cases where an experiment is repeated many times, a statistical analysis such as a chi-squared test may be required. If the evidence has falsified the hypothesis, a new hypothesis is required; if the experiment supports the hypothesis but the evidence is not strong enough for high confidence, other predictions from the hypothesis must be tested.
Once a hypothesis is strongly supported by evidence, a new question can be asked to provide further insight on the same topic. Evidence from other scientists and experience are frequently incorporated at any stage in the process.
Depending on the complexity of the experiment, many iterations may be required to gather sufficient evidence to answer a question with confidence, or to build up many answers to highly specific questions in order to answer a single broader question.
DNA example The basic elements of the scientific method are illustrated by the following example from the discovery of the structure of DNA: Previous investigation of DNA had determined its chemical composition the four nucleotidesthe structure of each individual nucleotide, and other properties. It had been identified as the carrier of genetic information by the Avery—MacLeod—McCarty experiment in but the mechanism of how genetic information was stored in DNA was unclear.
Watson hypothesized that DNA had a helical structure. This prediction was a mathematical construct, completely independent from the biological problem at hand. The results showed an X-shape. When Watson saw the detailed diffraction pattern, he immediately recognized it as a helix. Each step of the example is examined in more detail later in the article. Other components The scientific method also includes other components required even when all the iterations of the steps above have been completed: As a result, it is common for a single experiment to be performed multiple times, especially when there are uncontrolled variables or other indications of experimental error.
For significant or surprising results, other scientists may also attempt to replicate the results for themselves, especially if those results would be important to their own work.
Some journals request that the experimenter provide lists of possible peer reviewers, especially if the field is highly specialized. Peer review does not certify correctness of the results, only that, in the opinion of the reviewer, the experiments themselves were sound based on the description supplied by the experimenter.
If the work passes peer review, which occasionally may require new experiments requested by the reviewers, it will be published in a peer-reviewed scientific journal. The specific journal that publishes the results indicates the perceived quality of the work.
This allows scientists to gain a better understanding of the topic under study, and later to use that understanding to intervene in its causal mechanisms such as to cure disease. The better an explanation is at making predictions, the more useful it frequently can be, and the more likely it will continue to explain a body of evidence better than its alternatives. The most successful explanations — those which explain and make accurate predictions in a wide range of circumstances — are often called scientific theories.
Most experimental results do not produce large changes in human understanding; improvements in theoretical scientific understanding typically result from a gradual process of development over time, sometimes across different domains of science. In general, explanations become accepted over time as evidence accumulates on a given topic, and the explanation in question proves more powerful than its alternatives at explaining the evidence.
Often subsequent researchers re-formulate the explanations over time, or combined explanations to produce new explanations. Tow sees the scientific method in terms of an evolutionary algorithm applied to science and technology.
How the Scientific Method Works
That is, no theory can ever be considered final, since new problematic evidence might be discovered. If such evidence is found, a new theory may be proposed, or more commonly it is found that modifications to the previous theory are sufficient to explain the new evidence. The strength of a theory can be argued[ by whom? Theories can also become subsumed by other theories. For example, Newton's laws explained thousands of years of scientific observations of the planets almost perfectly.
However, these laws were then determined to be special cases of a more general theory relativitywhich explained both the previously unexplained exceptions to Newton's laws and predicted and explained other observations such as the deflection of light by gravity.
Thus, in certain cases independent, unconnected, scientific observations can be connected to each other, unified by principles of increasing explanatory power. In subsequent modifications, it has also subsumed aspects of many other fields such as biochemistry and molecular biology. This demonstrates a use of photography as an experimental tool in science. Scientific methodology often directs that hypotheses be tested in controlled conditions wherever possible. This is frequently possible in certain areas, such as in the biological sciences, and more difficult in other areas, such as in astronomy.
The practice of experimental control and reproducibility can have the effect of diminishing the potentially harmful effects of circumstance, and to a degree, personal bias. For example, pre-existing beliefs can alter the interpretation of results, as in confirmation bias ; this is a heuristic that leads a person with a particular belief to see things as reinforcing their belief, even if another observer might disagree in other words, people tend to observe what they expect to observe.
A historical example is the belief that the legs of a galloping horse are splayed at the point when none of the horse's legs touches the ground, to the point of this image being included in paintings by its supporters. However, the first stop-action pictures of a horse's gallop by Eadweard Muybridge showed this to be false, and that the legs are instead gathered together. Such proto-ideas are at first always too broad and insufficiently specialized.
Once a structurally complete and closed system of opinions consisting of many details and relations has been formed, it offers enduring resistance to anything that contradicts it.
MacKay has analyzed these elements in terms of limits to the accuracy of measurement and has related them to instrumental elements in a category of measurement. The scientific community and philosophers of science generally agree on the following classification of method components. These methodological elements and organization of procedures tend to be more characteristic of natural sciences than social sciences.
Nonetheless, the cycle of formulating hypotheses, testing and analyzing the results, and formulating new hypotheses, will resemble the cycle described below.
Who Invented the Scientific Method?
The scientific method is an iterative, cyclical process through which information is continually revised. These activities do not describe all that scientists do see below but apply mostly to experimental sciences e. The elements above are often taught in the educational system as "the scientific method".
For example, when Einstein developed the Special and General Theories of Relativity, he did not in any way refute or discount Newton's Principia. On the contrary, if the astronomically large, the vanishingly small, and the extremely fast are removed from Einstein's theories — all phenomena Newton could not have observed — Newton's equations are what remain.
Einstein's theories are expansions and refinements of Newton's theories and, thus, increase confidence in Newton's work. A linearized, pragmatic scheme of the four points above is sometimes offered as a guideline for proceeding: Characterizations The scientific method depends upon increasingly sophisticated characterizations of the subjects of investigation.
The subjects can also be called unsolved problems or the unknowns. For example, Benjamin Franklin conjectured, correctly, that St. Elmo's fire was electrical in naturebut it has taken a long series of experiments and theoretical changes to establish this. The systematic, careful collection of measurements or counts of relevant quantities is often the critical difference between pseudo-sciencessuch as alchemy, and science, such as chemistry or biology.
Scientific measurements are usually tabulated, graphed, or mapped, and statistical manipulations, such as correlation and regressionperformed on them. The measurements might be made in a controlled setting, such as a laboratory, or made on more or less inaccessible or unmanipulatable objects such as stars or human populations. The measurements often require specialized scientific instruments such as thermometersspectroscopesparticle acceleratorsor voltmetersand the progress of a scientific field is usually intimately tied to their invention and improvement.
I am not accustomed to saying anything with certainty after only one or two observations. The uncertainty is often estimated by making repeated measurements of the desired quantity. Uncertainties may also be calculated by consideration of the uncertainties of the individual underlying quantities used.
Counts of things, such as the number of people in a nation at a particular time, may also have an uncertainty due to data collection limitations. Or counts may represent a sample of desired quantities, with an uncertainty that depends upon the sampling method used and the number of samples taken. Definition Measurements demand the use of operational definitions of relevant quantities. That is, a scientific quantity is described or defined by how it is measured, as opposed to some more vague, inexact or "idealized" definition.
For example, electric currentmeasured in amperes, may be operationally defined in terms of the mass of silver deposited in a certain time on an electrode in an electrochemical device that is described in some detail. The operational definition of a thing often relies on comparisons with standards: The scientific definition of a term sometimes differs substantially from its natural language usage. For example, mass and weight overlap in meaning in common discourse, but have distinct meanings in mechanics.
Scientific quantities are often characterized by their units of measure which can later be described in terms of conventional physical units when communicating the work. New theories are sometimes developed after realizing certain terms have not previously been sufficiently clearly defined.
For example, Albert Einstein 's first paper on relativity begins by defining simultaneity and the means for determining length. These ideas were skipped over by Isaac Newton with, "I do not define timespace, place and motionas being well known to all.
Francis Crick cautions us that when characterizing a subject, however, it can be premature to define something when it remains ill-understood. His cautionary example was the gene; the gene was much more poorly understood before Watson and Crick's pioneering discovery of the structure of DNA; it would have been counterproductive to spend much time on the definition of the gene, before them.
DNA-characterizations The history of the discovery of the structure of DNA is a classic example of the elements of the scientific method: Researchers in Bragg's laboratory at Cambridge University made X-ray diffraction pictures of various moleculesstarting with crystals of saltand proceeding to more complicated substances. Using clues painstakingly assembled over decades, beginning with its chemical composition, it was determined that it should be possible to characterize the physical structure of DNA, and the X-ray images would be the vehicle.
It took thousands of years of measurements, from the ChaldeanIndianPersianGreekArabic and European astronomers, to fully record the motion of planet Earth. Newton was able to include those measurements into consequences of his laws of motion.