WhatsApp was officially made available for PCs through a web client, under the name WhatsApp Web , in late January 2015 through an announcement made by Koum on his Facebook page: "Our web client is simply an extension of your phone: the web browser mirrors conversations and messages from your mobile device—this means all of your messages still live on your phone". The WhatsApp user's handset must still be connected to the Internet for the browser application to function. All major desktop browsers are supported except for Microsoft Internet Explorer . WhatsApp Web's user interface is based on the default Android one.
This is an investigation of whether the real world behaves as predicted by the hypothesis. 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, ., to search for and test those experiments that seem most doubtful. Large numbers of successful confirmations are not convincing if they arise from experiments that avoid risk.  Experiments should be designed to minimize possible errors, especially through the use of appropriate scientific controls . 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 placebos , are 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, ., that the test equipment is working properly, and a failure may be a failure of one of the auxiliary hypotheses. (See the Duhem–Quine thesis .) Experiments can be conducted in a college lab, on a kitchen table, at CERN's Large Hadron Collider , at the bottom of an ocean, on Mars (using one of the working rovers ), and 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.