can we call an area with no matter in it but has EM waves passing through it a vacuum?
If possible, we know that EM waves are made of photons(for visible light) that means there are some particles going thru that space. so how can it be a vacuum?
So what exactly is a vacuum?
2007-03-22 05:13:52 · 9 answers · asked by sh 1 in Science & Mathematics ➔ Physics
another issue: we say there is a vacuum in HG barometers. But we also know that thousands of neutrinos pass thru the earth every second. So that mean they might pass thru this barometer. So that means we can never create a vacuum on Earth???
2007-03-22 05:18:09 · update #1
*.. Any pressure below that of the atmosphere is called 'Vacuum'.
*..Total vacuum is the complete absence of matter.
*..A total vacuum does not exist but, it is considered that outer space is about the closest we can get.
..On an absolute scale, total vacuum is classed as minus the atmosphere and is equal to Zero mmHg. (760 - 760 mmHg)
or Absolute Zero Pressure.
..Or, 14.7 - 14.7 = Zero psi. This is called:
.. 0 psia (absolute), or.. -14.7 psig (gauge), .. 0"Hg, ..etc.
2007-03-22 12:15:34 · answer #1 · answered by Norrie 7 · 0⤊ 0⤋
Actually, the problem is even more troublesome than what you have stated so far. Even if there weren't photons and neutrinos going through some area of space, the quantum level fluctuations would create particles in that space for brief periods of time. So there really is no way to have *nothing* in an area of space. It is even an *active* field of investigation to describe what the 'ground state' of a vacuum is when taking into account quantum effects.
The work aorund is to not really talk about a pure vaccum, but to talk about the pressure or density in some area. Yes, the photons and even the neutrinos produce a slight pressure. Whether that degree of pressure is significant depends on exactly what you want to do. For cosmology, the pressure and density of a 'vacuum' are very important quantities and photons have a big part to play.
2007-03-22 07:28:38 · answer #2 · answered by mathematician 7 · 0⤊ 0⤋
There are degrees of vacuum. In the case of the barometer, the vapor pressure of mercury is quite small and hence the space above the mercury was called Toricellian vacuum after the scientist who desribed it. So, even without neutrinos passing through it, you have a few mercury molecules moving about.
In space, there is cosmic background radiation through out the universe and if we accept your definition of vacuum, yes, we have no true vacuum. Conventional vacuum means no siginificant pressure exerted by the molecules. Very high vacuum, ultra high vacuum and ultimate vacuum etc. were words coined to describe the degree of vacuumness as techniques to develop vacuum progressed.
2007-03-22 06:47:00 · answer #3 · answered by Swamy 7 · 0⤊ 0⤋
in English: empty space between two objects ;)
in Science: A space totally empty of matter.
you know there is nothing as 100% so i would say there is no "absolute vacuum". So in other words vacuum can be defined as "A space relatively empty of matter." I think this answers your question, " can we call an area with no matter in it but has EM waves passing through it a vacuum?" Yes!
2007-03-22 09:39:09 · answer #4 · answered by Anonymous · 0⤊ 0⤋
A vacuum is a volume of space that is essentially empty of matter, so that gaseous pressure is much less than standard atmospheric pressure. but space can never be perfectly empty. A perfect vacuum with a gaseous pressure of absolute zero is a philosophical concept that is never observed in practice, not least because quantum theory predicts that no volume of space is perfectly empty in this way.
2007-03-22 06:50:22 · answer #5 · answered by Jewl 2 · 0⤊ 0⤋
Hi Shan,
In my opinion Space is a vaccum. A vaccum is something that is void of any matter. The sky (our atmosphere) contains nitrogen and oxygen and other stuff. Therefore no vaccum since there is matter. Outside the very boundary of the atmosphere is nothingness.
This is generally accepted by you have to remember that there is really no such thing as a true vaccum in our universe. You will always have something whether its a light particle or something popping in and out of existance.
2007-03-22 05:38:11 · answer #6 · answered by Anonymous · 0⤊ 0⤋
Vacuum actually describes a variety of conditions of a volume of space. What is one person's vacuum is high pressure to another. EM waves don't count because they have no mass.
Here's a pretty good write up
http://en.wikipedia.org/wiki/Vacuum
2007-03-22 05:23:58 · answer #7 · answered by Gene 7 · 0⤊ 1⤋
I'm not going to argue with u although im sure ur rong ...but if ur right- and the suction that we call a vacuum; by definition cannot be a vacuum. then it would be called something else
2007-03-22 05:24:47 · answer #8 · answered by andy_114 2 · 0⤊ 0⤋
http://en.wikipedia.org/wiki/Vaccuum
2007-03-22 05:22:11 · answer #9 · answered by J-Far 6 · 1⤊ 1⤋