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Physics, Astronomy & Cosmology / Re: What would happen if I connected a pipe from the atmosphere into space?

« on: 05/12/2015 23:34:45 »

Absolutely nothing will happen. The atmosphere already extends from the ground to the edge of space, by defintion of "edge of space".

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Physics, Astronomy & Cosmology / Re: What would happen if I connected a pipe from the atmosphere into space?

« on: 05/12/2015 13:41:02 »

What would be the possible outcomes if a connecting pipe is kept on the boundary of atmosphere and space with one end in atmospheric layer and the other in the space.. []

Please present all topic titles as a question, as per site guidelines - Moderator.

The atmosphere will gather at the bottom of the pipe lessening in density the further up the pipe you measure. The top of the pipe that is in space, will probably ''melt'' or something similar.

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Physics, Astronomy & Cosmology / Re: What would happen if I connected a pipe from the atmosphere into space?

« on: 05/12/2015 13:26:37 »

What would be the possible outcomes if a connecting pipe is kept on the boundary of atmosphere and space with one end in atmospheric layer and the other in the space..

A lot of flying collisions with the pipe  []

--
lightarrow

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Physics, Astronomy & Cosmology / Re: Just curious :-|

« on: 04/12/2015 20:59:14 »

After initial air pressure equalization at both ends of the pipe, not very much.

• The end of the pipe that is in space will have a very low air pressure, matching the vacuum around it.
  
• The end of the pipe that is in the atmosphere will have a higher air pressure, matching the atmosphere around it.
  
• And gravity will ensure that there is a smooth gradation in air pressure between one end of the pipe and the other.

There will be no continual rush of air from the atmosphere up the pipe, and out into space, that you could use to power a generator. This would be a form of perpetual motion machine, which the Patent Office automatically rejects unless they are accompanied by a working model.

By the way, I can think of a number of very useful applications for a mechanism that is able to suspend a pipe at the outer edges of our atmosphere!

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Physics, Astronomy & Cosmology / Re: Is a stationary object in space really stationary?

« on: 04/12/2015 09:36:55 »

stationary with respect to what??

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Physics, Astronomy & Cosmology / What's the difference between general & special relativity?

« on: 11/10/2016 21:12:23 »

100 years ago, Einstein's theory of general relativity changed the world. Before that though, came special relativity.

Read the article then tell us what you think...

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Physics, Astronomy & Cosmology / Re: Does a perfect blackbody exist?

« on: 03/12/2015 05:31:38 »

Questions along the lines of "Does a perfect X exist?" or "does an ideal Y exist?" are almost universally, unequivocally answered, "no." Unless there is no way for something not to be perfect (a photon will always be a perfect photon, and behave as such, because there is no way for a photon to be imperfect, as far as I know.)

"Perfect" and "ideal" usually mean "fits perfectly to a simple model" (and all our models are far more simplistic than what's actually going on). We make approximations, assumptions and take mathematical liberties that we use until the model stops giving reasonable answers, or the precision required for a task. Then we resort to more complex models, based on theory or just optimized with empirically determined parameters until we can solve the problem at hand.

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Physics, Astronomy & Cosmology / Re: Does a perfect blackbody exist?

« on: 03/12/2015 03:49:20 »

My theoretical frictionless mechanism doesn't have any friction.

Doesn't have any weight either.

It can't absorb light though

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Physics, Astronomy & Cosmology / Re: Does a perfect blackbody exist?

« on: 03/12/2015 02:08:53 »

Is there anything like perfect blackbody which absorbs light completely and reflects nothing

A "perfect blackbody" would absorb radiation at all wavelengths, including those invisible to the human-eye, e.g. Infra-Red,  Ultra-Violet, Radio-Frequency, X-Rays, etc. So "perfect blackbody" an idealized concept, not existing in reality , ( like frictionless mechanisms ).

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Physics, Astronomy & Cosmology / Re: Does a perfect blackbody exist?

« on: 02/12/2015 23:54:47 »

I think someone recently invented an even blacker black. This one uses gold nanoparticles and nanorods, which interfere with the incident radiation of different sizes and absorb the energy, meaning that even less radiation is reflected.

So, essentially, black just got blacker...

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Physics, Astronomy & Cosmology / Re: perfect blackbody?

« on: 02/12/2015 20:31:27 »

Vantablack absorbs 99.96% of light. That's pretty damn close. It appears 2D to the human eye, and it's created with carbon nanotubes.

There are also black holes

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Geology, Palaeontology & Archaeology / Re: What has caused this stripey pattern on of the wall of this building?

« on: 02/12/2015 12:33:01 »

Some kinda fungus or algae from plants and the atmosphere also looks humid to so have a peace of it and take it to chemist or biologist

Stucco and other forms of plaster contain lime; CaO, as one of the main ingredients. Lime, is often used on lawns to lower the pH of the soil, since it is alkaline or has high pH. If the plaster is not mixed properly, such as not enough water or too much lime, then the finished stucco will be hot; high pH. The unreacted lime will also leach out over time, after the surface gets wet and dries during rain cycles. The answer could be one bad batch of plaster under the overhang.

Another possibility is the White House in the USA is white because the siding was lime washed. In this process, they will mix a slurry of water and lime, and this will be painted onto the surface to give a white color. If that was the case, under the overhang will not dry the same way as outside the overhang. The striping could also be an artifact of how it was applied, since the lime wash is thick. In painting terms he did not keep a wet edge, but had double coat overlap. Often the apprentice plasterer would be given a small job like, with the larger expanses left for the experts. 

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Physics, Astronomy & Cosmology / Re: definition of stationary.

« on: 01/12/2015 15:12:08 »

When constant gravity is acting on a well balanced and resting object. Then and only then the object is considered to be stationary   []

Only stationary relative to the ground stating body in an inertial reference frame.    v(A)=X  v(B)=0    a{B}=g=9.82m/s=N     where v is velocity and ''a'' is acceleration and N is newtons of force , (A) =M₁   (B)=M₂

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Geology, Palaeontology & Archaeology / Re: What has caused this stripey pattern on of the wall of this building?

« on: 01/12/2015 13:46:27 »

... Some kinda fungus or algae...

We've had stripey-fungus on this forum previously , see ...
http://www.thenakedscientists.com/forum/index.php?topic=49171.0;nowap

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Physics, Astronomy & Cosmology / Re: Is a stationary object in space really stationary?

« on: 01/12/2015 07:44:06 »

On the sub atomic scale, nothing is truly stationary, so there's also that to consider.  []

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Physics, Astronomy & Cosmology / Re: Is a stationary object in space really stationary?

« on: 30/11/2015 18:15:49 »

As far as a bug on the needle is concerned, it is stationary. Even if it is accelerating in a gravitational field, free fall = stationary within the frame of reference of the bug.

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Physics, Astronomy & Cosmology / Re: stationary object are really stationary!!?

« on: 30/11/2015 14:18:08 »

Can we put a needle completely stationary in space? And waht can prove that it is actually an absolute stationary?  [B)]

No we can not, gravity will take hold of the needle and the needle will move towards the nearest gravitational body.   There is no stationary state in our visual Universe.  Everything is always moving.

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Physics, Astronomy & Cosmology / Re: By how much has the mass of the Earth changed over the planet's lifetime?

« on: 29/11/2015 09:53:41 »

The Earth is losing between 50,000 and 60,000 tonnes of mass each year.

How do we arrive at this figure?

We need to consider the "mass balance"; that is, how much material is arriving here that wasn't here to start with, and how much material is leaving the planet.

First, let's consider how the Earth is gaining mass:

Earth is continuously gaining mass in the form of dust particles, and sometimes larger bodies, that fall in from space. Scientists estimate that this adds up to about 40,000 tonnes of material each year.

At the same time, using planet-wide temperature readings from NASA and other sources, one can see that the planet is warming up, or gaining thermal energy. This is coming from the Sun, and if energy is added to a system, then since E=mc^2, there is a corresponding increase in mass. Based on present data, this is probably adding a small amount of mass to the planet each year, of the order of 200 tonnes or so.

So the total mass gained by the planet each year is about 40,000 tonnes.

At the same time, the Earth is losing heat energy from its core as radioactive elements decay. Based on estimates of how much energy exits in this way, the mass loss is trivial though at about 16 tonnes per year.

More significant is what happens in the outer reaches of our atmosphere where the gravity field is weaker and lighter elements, like helium and hydrogen are hard to hold on to.

Earth loses about 1600 tonnes of helium to space each year like this. More dramatically, physicists estimate that we're losing about 3 kilograms per second of hydrogen in the same way. This adds up to 95,000 tonnes of hydrogen over a year.

So the net change in mass each year is 40,000 tonnes coming in, minus 96,000 tonnes going out. So the Earth loses about 56,000 tonnes of mass every year.

That sounds like a lot, but actually, as a proportion of the mass of the planet, which is 6 x10^21 tonnes, it's about 0.000000000000001% per year, so probably not worth losing any sleep over!