The near-vacuum extending between the planets and stars, containing small amounts of gas and dust. Also called outer space to refer to the physical universe beyond the Earth's atmosphere.

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7
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2answers
701 views

What's the difference between space and time?

I'm having a hard time understanding how changing space means changing time. In books I've read people are saying "space and time" or "space-time" but never explain what the difference is between the ...
12
votes
13answers
2k views

What are the mechanics by which Time Dilation and Length Contraction occur?

What are the mechanics of time dilation and length contraction? Going beyond the mathematical equations involving light and the "speed limit of the universe", what is observed is merely a phenomenon ...
6
votes
5answers
865 views

What would ACTUALLY happen to a person jettisoned into space?

[insert obligatory statement of my lack of knowledge in physics] Alright, so we have all seen the movies where someone gets blasted out of the airlock on their starship, or their suit decompresses ...
10
votes
1answer
437 views

How vacuous is intergalactic space?

You often hear intergalactic space is an example for a very good vacuum. But how vacuos is space between galaxy clusters and inside a huge void structure? Are there papers quoting a ...
9
votes
3answers
833 views

Can black holes actually merge?

If time stops at the event horizon, can we ever detect two black holes merging? In other words, if you are a short distance away, would you encounter a spherically symmetric gravitational field, or a ...
17
votes
2answers
3k views

How does space affect the human body (no space suit, no space craft)

How does "outer space" affect the human body? Some movies show it as the body exploding, imploding or even freezing solid. I know space is essentially a vacuum with 0 pressure and the dispersion of ...
9
votes
6answers
2k views

Does anything exist in the intergalactic space?

I am a part time physics enthusiast and I seldom wonder about the intergalactic space. First, it is my perception that all(almost all) the objects in the universe are organized in the forms of ...
4
votes
2answers
1k views

“Artificial gravity” on a rotating space stations

There have been a lot of sci-fi shows recently using the "rotating space station" explanation for gravity on space stations. After watching these videos: ...
2
votes
5answers
478 views

what are dimensions?

First, discrete examples. In a computer screen I can specify any "2D" point with just one single number (pixel order starting count from first at upper left, and going on, left2right and up2down ...
64
votes
7answers
6k views

How can a black hole produce sound?

I was reading this article from NASA -- it's NASA -- and literally found myself perplexed. The article describes the discovery that black holes emit a "note" that has physical ramifications on the ...
16
votes
2answers
4k views

What is the possibility of a railgun assisted orbital launch?

Basic facts: The world's deepest mine is 2.4 miles deep. Railguns can acheive a muzzle velocity of a projectile on the order of 7.5 km/s. The Earth's escape velocity is 11.2 km/s. It seems to me ...
5
votes
3answers
583 views

Will a machine or a technique ever be possible that allows artificial gravity in interplanetary space?

Will a machine or a technique ever be possible that allows artificial gravity in interplanetary space? And I ask out of pure curiosity. I know there is the "Vomit Comet" that allows for a non-gravity ...
6
votes
1answer
313 views

Has Voyager 1 entered a solar radiation belt?

The Voyager 1 probe was sent out in 1977 to go where no man made object has gone before, after more than 35 years it’s still going strong. It’s now 124 AU away from Earth and many are wondering when ...
1
vote
6answers
5k views

Does vacuum (empty space) exist? [closed]

Added: 5 times down vote for now! Down voter is this religion or physics, please try to explain your decision. I'm confused about this. In physics we know for a vacuum, but I think that there is a ...
5
votes
3answers
573 views

An electromagnetic space elevator?

If you surround the equator with a continuous Niobium Tin superconductor ring, and ran somewhere near but less than the maximum current density through, the magnetic field of the Earth would support ...
8
votes
4answers
255 views

Direct exposure to the vacuum of space

I was watching a few sci-fi movies and was wondering the real science explaining what would happen if you were to be subject to the conditions of outerspace. I read the wikipedia article on space ...
4
votes
2answers
332 views

Sum total distance of electrons on a spherical surface

What is the sum total distance between every possible pair of point charges when there are n point charges on a spherical surface? All point charges can only and are located on the infinitesimal ...
2
votes
2answers
335 views

Speed of light in a vacuum

I see many references to the speed of light in a vacuum implying that it is only truly a constant measurement in a vacuum. I can live with that, but what kind of vacuum? Are we still talking about ...
2
votes
3answers
796 views

If the earth left the solar system for interstellar space. How long would it take for atmosphere to freeze

If the earth left the solar system for some reason. Assuming its moving at the same velocity it's currently exhibiting. How long would it take for the atmosphere to freeze. Would we get methane ...
1
vote
5answers
660 views

Nothing vs. empty space

This question quotes Hawking saying: [...] you enter a world where conjuring something out of nothing is possible (at least, for a short while). That's because at this scale particles, such as ...
12
votes
2answers
299 views

Why were space physicists wrong about the location of the heliopause?

The heliopause is now estimated to be something around 100 AU (1 AU = Astronomical unit = about the earth sun distance). See the wikipedia article: http://en.wikipedia.org/wiki/Heliosphere From ...
6
votes
4answers
944 views

What causes the permittivity and permeability of vacuum?

When light travels through a material, it gets "slowed down" (at least its net speed decreases). The atoms in the material "disturb" the light in some way which causes it to make stops on its path. ...
3
votes
1answer
313 views

How much time has passed for Voyager I since it left the Earth, 34 years ago?

34 years have passed since Voyager I took off and it's just crossing the solar system, being approximately at 16.4 light-hours away. How much time have passed for itself, though?
3
votes
4answers
2k views

How do we know that earth moves around sun and that too in elliptical orbit

I know the basics of solar system like how earth moves around sun, and that we have so many planets, elliptical orbit of earth, and how far is sun from earth etc etc. I want to take a step back and ...
2
votes
1answer
2k views

What are the temperatures of objects in Low Earth Orbit (LEO)?

What is the temperature of objects in Low Earth Orbit? Consider LEO to be 600km to 800km.
18
votes
7answers
1k views

What grounds the difference between space and time?

We experience space and time very differently. From the point of view of physics, what fundamentally grounds this difference? Dimensionality (the fact that there are three spatial dimensions but only ...
21
votes
1answer
535 views

How do we know that these radio bursts are from billions of light-years away?

NASA just announced that they detected the first radio bursts from outside of our galaxy. Astronomers, including a team member from NASA's Jet Propulsion Laboratory in Pasadena, Calif., have ...
19
votes
3answers
9k views

How long does it take to travel 36 light years with tolerable acceleration and deceleration?

The recent discovery of HD85512b only 36 light years from Earth has promising attributes to harbor life. Assuming we want to travel there, we cannot instantaneously jump to light speed, (StarTrek ...
1
vote
4answers
2k views

Visualizing Electromagnetic Waves in 3D Space

I did one module of physics for my GCSE one year ago which taught me about transverse EM waves & the EM spectrum, but since then, I do not understand how a wave would move in 3D space. Can someone ...
5
votes
5answers
1k views

Why can't airplanes just keep going up? [duplicate]

Possible Duplicate: Why do space crafts take off with rockets instead of just ascending like an aircraft until they reach space? Ignoring that the engines only work in air, so say its a ...
6
votes
5answers
4k views

Why can't a spaceship accelerate for ever? Since there is no friction in space

I have seen many answers like: because we don't have infinite energy, because of gravity, because it is impossible, because of physics. But they don't really answer my question.. I mean if there is ...
6
votes
3answers
692 views

Would a fast inter-stellar spaceship benefit from an aerodynamic shape?

Some (generous) assumptions: We have a spaceship that can reach a reasonable fraction of light speed. The ship is able to withstand the high energies of matter impacting at that speed. Given the ...
5
votes
3answers
3k views

How do they produce air on the ISS?

How do they provide air on the ISS? I know it is produced by electrolysis but is that all they breathe, hydrogen and oxygen? The air here on Earth contains other things like nitrogen. Do the people ...
5
votes
2answers
1k views

Escape Velocity of Asteriod 243 Ida

I was reading about this asteroid (apparently, it has a moon, isn't that awesome?) and I started thinking about if I was on this asteroid, and I jumped, would I fall off? It's been a while since I ...
4
votes
2answers
387 views

Would a sneeze by a cosmonaut in a spacesuit affect his movement?

Naive question; feel free to shoot me down It is a truism that any motion in space would continue indefinitely unless it is opposed by an external force. If a cosmonaut were to sneeze within his/her ...
3
votes
5answers
3k views

If a space ship accelerated constantly, would its astronauts constantly feel the forward movement?

I know that if a space ship suddenly traveled very fast, its astronauts would be fly against the back wall, potentially getting hurt. If the space ship suddenly stopped, they would also fly against ...
3
votes
1answer
195 views

Hamiltonians and Lagrangians, Euclidean and Hyperbolic: Are they related?

The Lagrangian of a system is the difference between its kinetic energy $T$ and potential energy $V$, and is relativistically invariant: $L = T - V$ The Hamiltonian of the same system is the sum ...
3
votes
1answer
154 views

Keeping air in a well

Let's say I've got an Earth-like planet with no atmosphere: it's just a barren ball of rock. I want to live there, but I don't like domes, so instead I'm just going to dig a big hole and let gravity ...
9
votes
5answers
4k views

If I take a bottle of air into space, and open it, where does it go?

It seems to me that space doesn't have any/much air, and if my bottle is full of air, when I open it, where does the air go?
7
votes
2answers
897 views

What does the sky look like to human eyes from orbit?

There are numerous pictures, obviously, of the blackness of space from the shuttle, the space station, and even the moon. But they all suffer from being from the perspective of a camera, which is not ...
5
votes
2answers
623 views

What is the largest sphere of liquid water that could exist in space held together under it's own gravity? [duplicate]

What is the largest theoretical sphere of liquid water that could exist in space held together under it's own gravity? I've always wondered if a planet the size of earth could exist as a single volume ...
4
votes
2answers
110 views

Orbit in the vacuum

As the space is a vacuum and there is no friction in space, Can we assume that, if we place an object in gravity in exactly the right distance from a planet with gravity and in the right acceleration, ...
4
votes
5answers
404 views

Does a interstellar spacecraft traveling at relativistic velocity require continous thrust to maintain velocity?

Assuming completely empty space, does a spacecraft traveling at 0.5 C require continuous thrust to avoid deceleration? If the spacecraft is traveling at 0.5 C, does it's relativistic mass act upon ...
4
votes
7answers
2k views

What properties do you need for building a tower?

When I was a boy I used to daydream about building a tower so tall that the top of it would stick out of the top of Earth's atmosphere project into near space. There would perhaps be a zero gravity ...
3
votes
2answers
247 views

Do black holes accelerate in spin as they obtain more mass?

It is known that - When a star collapses during the formation of the black hole, the black hole obtains the spin of the star which it collapsed from... What I'd like to know is, If this spin ...
3
votes
3answers
539 views

How would you move without gravity?

I'm wondering how would you move without gravity? You would still have air pressure at 1Atm. Would you "swim" in the air or would you have do something else?
2
votes
1answer
141 views

The range of light

It occurs to me that the empirical evidence shows that there is a point out in space where light stops coming from. Putting aside the expansion of the universe for a second, and focusing strictly on ...
1
vote
2answers
172 views

Get into orbit from the Redbull jump position to a satellite position by using a cord/rope?

Its difficult to put this into the title. I was watching the Redbull Jump and noticed that the height of this is at 39 kilometres (24 mi) the atmosphere pressure is at I believe about 0.4% of that at ...
0
votes
1answer
254 views

Composition of solar spectrum

I read some where that there are three types of UV and infrared rays namely UV-A, UV-B, UV-C and near infrared, mid infrared and far infrared. Which is the most abundant among the the three in ...
0
votes
2answers
215 views

Why should space be empty? [duplicate]

Possible Duplicate: How vacuous is intergalactic space? The emptiness of space is explained in many articles... But, space does contain some matter due to these possible reasons: During ...