New answers tagged

0

When we say field, you shouldn't immediately think electric field. You should instead think of the easier scalar field. Also the electric field is not J/C. That is the voltage potential function. Now look at how the action of the field configuration depends on the field you are looking at. For example, it might be $S=\int d^4 x \partial^\mu \phi \partial_\mu ...


1

In a word, no. Getting into space is a matter of achieving enough velocity to overcome the Earth's gravitational influence, not about buoyancy. You can use buoyancy to get to the edge of the Earth's atmosphere, not beyond. We don't fill a rocket with helium so it'll float into space, nor do we use balloons to get beyond the edge of the Earth's atmosphere.


2

The vacuum does not pull, it is an illusion, what happens is the molecules on the air outside hit the piston and produces a force inwards, and because on the inside there is very little gas (or none if there were a perfect vacuum) there is no force to stop the piston prom moving inwards.


1

Phenomena is called Cold Welding The reason for this unexpected behavior is that when the atoms in contact are all of the same kind, there is no way for the atoms to “know” that they are in different pieces of copper. When there are other atoms, in the oxides and greases and more complicated thin surface layers of contaminants in between, the ...


0

It all depends on how clean the surface of the metal are. If there are oxides and impurities on the surfaces they will not bond together. However if the surfaces are ultra clean with no gas molecules from the atmosphere adhering to them, which on Earth would require them to be an ultra high vacuum chamber, then the surfaces would join together having made ...


2

What is meant by a “change in volume of a system”? "Change in volume of a system" means "change in volume of a system", not anything else. System is a hypothetical concept. There is no specified system before we define it. We ourselves choose and define system. When someone talks about a system defined by himself/herself, he/she talks about that system not ...


0

there are two types of vacuum in physics. one with and one without radiation (radiation being any kind of electromagnetic interaction, or photons). Sloppy scientist call a matterless volume vacuum, although it still has radiation (and therefor contains energy). You can imagine that it is very hard to achieve a true vacuum in which only the vacuumfluctuation ...


1

Vacuum or pressure is quantified in terms of bar or torr. 1 bar or 760 torr is roughly one atmosphere and in terms of vacuum measurement 1 mili-bar is taken as almost equal to 1 torr. at 1 bar pressure and at room temperature the number of atoms per cc is ~$2\times 10^{19}$. The number of particles per cc in vacuum can range from $10^{-4}$ to $10^6$. The ...


2

My essay Misconceptions about Virtual Particles explains in detail the difference between the popular science view of virtual particles popping in and out of existence and the physical science view of virtual particles as useful (but literally virtual) imagery for talking about complicated integrals for the computation of scattering amplitudes. From the ...


0

It is really really really difficult to get a vacuum of 1E-10 Pa at room temperature when surrounded by a 1E+5 Pa atmosphere (sea level on Earth). The answer referring to Penning Traps needs to be understood in the context of the life-time of the antiprotons being on the order of seconds or less. So, unless your story has a method of creating and isolating a ...


1

OK this is pretty simple. When the soup cools the pressure drops below the outside pressure and seals. That was said already. But usually a soup container in a traditional bento box has a little push button valve on top that when pressed releases the vacuum within the container. Be sure to use the right container for your soup or look into getting one ...


-3

Space is the canvas on which the Universe is painted. Space is created when a Higgs wave (dark energy) intersects dark matter. When this happens, three things are created. Matter, energy and a whole lot of SPACE. Space has two known properties. First, Dr. E. tells us it can be warped. Second, I tell you it cannot be compressed. That being said, this reaction ...



Top 50 recent answers are included