chron44

Fair enough, c, the speed of light in vacuum, is a well established physical constant. It's universal and measured with good precision. One centimeter of c gives a persistent time frame. And this time frame gives 1 centimeter. And you imply that the scientific community have united in this, or are working on this definition? It's okay, this way of defining time, c, is a most accurate and stable form of a clock. Space and time sort of united. It still doesn't answer the issue completely, though giving the physical dimension of time. Thanks for the excerpt of this definition.

For to widen this thread one can notice how these three main tech's gives different outcomes if we compare these when placing each # 1, 2, and 3 first on earth and secondly on the moon. -How different "time" may "behave". 1. The hourglass or the pendulum acts slower on the moon than on earth. 2. The atomic clock, for example, goes faster on the moon. 3. The radioactive decay "clock" goes at the same phase on earth as on the moon. ~~~~~~~~~~ If these changes not actually behave as mentioned here, at least "time" is very different on earth than on the moon. -Relative these three tech's. How come? ~~~~~~~~~~ Time therefore should be scientifically defined (some type of formula) to be universal uniform or on the contrary not universal uniform. And we know according classical physics and GR/ SR/ QM- math, time also behave universal differently So, what is time in physics? This is a fair physics issue presented through these behavior examples.

"Cognitive abilities are not a topic in physics. This post belongs to another forum." -- Genady Well, refining my post a bit: I assume the halved "time" concept, for example, in the well established spacetime (GR/ SR) concept, is a physics issue. If we only discuss "time" used in science: What is time in physics? .. If persisting in my view of time being a physical issue, and not only a metaphysical subject. How can science at all deal with universal physical issues such as Newtonian and GR/ SR/ QM physics without the true scientifical "formula" for time? -How is time connected to these physics disciplines mentioned (Classical, GR/ SR/ QM)? -How can physicist truly understand these disciplines without an adequate time formula? -Like the famous E=mc^2. If people here at physics forum have another view on the issue of the time concept, I'll swap forum. This issue is raised here in a true physical aspect, however. (And I understand that length/ space also is not fairly explained in physics.)

Hi, new here, though most interested in physics and its elementary subjects. Have stayed around in physics sites at the internet since late 1990's. ~~~~~~~~~~~~~~~ And still the "universal" concept of "time" has never, to my knowledge, been satisfyingly explained in a physical and scientific manner. This may be caused by: 1. Time is a most enigmatic function/ behavior/ dimension in science. 2. People have cognitive difficulties in general which the concept of "time" is revealing. 3. Science and physics is generally a "young" human discipline. ~~~~~~~~~~~~~~~~ To my layman understaning one have measured time historically by three main technologies. 1. Pendulum, hourglass, sun-orbits, and so on. 2. Chronographs, (clocks - electrical, mechanical, atomic, crystal). 3. Radioactive steady decay technology. So, there are many ways in which time has been measured, still the origin of time is eluding our cognitive ability. /chron44