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.

learn more… | top users | synonyms

2
votes
1answer
42 views

How to construct a space which is translation invariant but not rotation invariant

I am just confused by the following idea. Consider a 3-dimensional translation invariant space, we now have 3 translation generators. Then let us start with a point, the full 3-dimensional space ...
0
votes
1answer
56 views

Could vacuum chambers lighten the load for space bound technology?

Would cavities of near vacuums in the head (or in the 6 x 6 blocks surrounding the rocket [for reentry temperatures]) of a rocket make it lighter so it can be sent out easier?
-1
votes
0answers
25 views

How it works a Hall Effect Thruster?

I'm an aerospace engineering student, currently doing an erasmus in Pisa, Italy. I was thinking about the Hall Effect Thrusters and how they are able to produce thrust. There's something that I don't ...
0
votes
0answers
30 views

How do we measure curvature of space? [duplicate]

I know according to general relativity, space-time is curved near mass. But I have also read that at large distances space can be curved too, and that Gauss was the first one to measure it. My ...
0
votes
2answers
51 views

If two pieces of the same type of metal touch in space, will they bond and be permanently stuck together? [duplicate]

Yesterday I was watching discovery channel, on a program they said that 'if two pieces of the same type of metal touch in space, they will be permanently stuck to each other.' Is it true..? If yes... ...
-2
votes
1answer
40 views

Space vacuum power

How strong is the vacuum in space? If possible in mph, or other easy to understand measurements...as someone else asked, "if you took a bottle of air into space and opened it, where would it go?" I'm ...
2
votes
1answer
33 views

What will happen if we establish a physical connection between ground and ionosphere?

https://en.wikipedia.org/wiki/Ionosphere The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth, stretching from a height of about 50 km (31 mi) ...
0
votes
2answers
60 views

why cannot longitudinal waves travel through space (vacuum)

'The reason sound can't travel through a vacuum is that sound needs a medium (solid, liquid or gas with real vibrating molecules) and not because it is a longitudinal wave' How does this make sense as ...
0
votes
1answer
66 views

What are the problems in the idea that a person would freeze to death in outer space?

It is said that the body would freeze to death, if left in outer space, which is true, since the temperature is around $3$K. But what are the flaws in this theory, in terms of thermodynamics (if we ...
0
votes
1answer
97 views

Can you see yourself in space? [closed]

Can one see them self in space if no near by star was in view? Is there enough star light to read once your eyes adjust?
0
votes
0answers
15 views

How could you slow down or change direction with photonic propulsion?

So you have a laser shooting at a sort of solar sail to transfer momentum in the forward direction but could you have an onboard laser and turn the laser around to hit another sail? How could you turn ...
0
votes
0answers
20 views

The force of a vacuum on a breached environment in space

Screenwriter and Physics newbie, not looking for hard numbers, but sort of a general idea of what the force of a breach in a sealed environment in space would be. In films in space, often the ship or ...
0
votes
1answer
36 views

Would a literal Air ship (boat) work?

If a set of very large airtight pontoons were made in the vacuum of space, would they float on top of the upper atmosphere? I thought about this while watching the last season of Mythbusters when they ...
4
votes
1answer
52 views

Will stars disappear from the sky when their particle horizon is outside the event horizon

Given that the universe is expanding at an accelerated rate, will there be a point where stars visible in the night sky will simply disappear from view when their particle horizon is outside the event ...
0
votes
0answers
44 views

Why does astronauts hair stick up, and not in other directions?

I understand that in microgravity it doesn't have to fall down, but why does it stick up, instead of each hair-strand going in a random direction?
3
votes
1answer
61 views

Helmet to helmet in vacuum - can we talk?

Usual SciFi scene. In a spacesuit, in vacuum, with the comms out for some reason. They want to talk, so the butt helmets together so sound can pass through. Questions are: a) Would it really work in ...
0
votes
0answers
47 views

Questions regarding space

A difficulty I face is when I think of space. I haven't studied GR or SR yet, but I really want to know what it is. What is space? Is it just the empty place where things are in reality, or something ...
0
votes
0answers
30 views

When space containing an extended mass contracts, what delivers or absorbs energy?

As my understanding goes, general relativity and the many theories that have sprung from it allow for the contraction and expansion of space. When such expanding (or contracting) space contains a ...
2
votes
0answers
43 views

How to find out diameter of some crater on moon using meteorite size and velocity?

I am looking for a formula to find out the diameter of a crater using meteorite size and velocity.
2
votes
0answers
76 views

Should we consider space and time as separate entity?

In general relativity, we think of space and time in spacetime framework. As some people say, metric tensor sign difference, along with our inability to go backward in time suggests that space and ...
0
votes
0answers
43 views

Boiling Water in the Vacuum of Space [duplicate]

In space: When you depressurize ice with a temperature of -72 degrees Celsius would it turn into water? Is there a stable temperature range in which water stays liquid? Does the temperature ...
0
votes
1answer
144 views

Is space really empty? [duplicate]

This guy here says space is not empty.. It explains how space inside nucleus is Full of fields. Does it mean to say gluons are present everywhere, even outside nucleus? Consider a region without any ...
0
votes
0answers
26 views

What would happen if another big bang occurred at the centre of the current universe? [duplicate]

If another Big Bang occurred now, at the centre of our universe, what would happen? As the rate of expansion is increasing, the two "layers" (if there were any) would never meet, in which case, would ...
0
votes
0answers
22 views

Seeing ourselves in the past [duplicate]

If we can see billions of light years into space how do we know we're not looking at our galaxy in the past?
1
vote
0answers
38 views

Do relativistic frames imply different realities? [duplicate]

From Einstein's principle of relativity space-time and mass are relative to the frame from which they are being observed. Now would that mean a ball moving at the speed of light wrt to earth would ...
1
vote
0answers
28 views

Orbital period of a satellite in Kerbal Space Program

Let me start off by saying I am really bad at maths and physics, but lately I have been trying to calculate the orbital period of a satellite I have put in orbit around a planet called Kerbin in a ...
3
votes
3answers
91 views

Why would we freeze in space if there is no matter to conduct the heat away from us?

If a near perfect vacuum is assumed to be in space, how can heat leak around from our body for example? Although theoretically energy wishes to spread equally all around, it still needs a medium to ...
1
vote
2answers
49 views

How is the temperature of a star related to gravity?

As far as I know the Sun gets its energy from the fusion reaction, where Hydrogen is converted into Helium. I was watching an episode of Cosmos: A spacetime odyssey. There Neil deGrasse Tyson said, ...
2
votes
1answer
121 views

Is near light speed travel possible? Likely?

I was contemplating the possibility of sending an interstellar probe that can produce results in a reasonable time frame. For such a mission to be realistic, the spacecraft would have to travel at ...
1
vote
2answers
242 views

Red Photon Blue Photon

Why in space red light travels farther and is more observed in dying stars before a star becomes a black hole? while on Earth in water and air the blue light travels the farthest. For example: a T....
1
vote
0answers
26 views

Simulating Debris Burn Up Upon Atmospheric Reentry

For work I need to model Debris (1 gram to no more than 1000 km) burn-up upon reentry. I can't seem to find much information regarding this. I feel like I am looking for the wrong terms or something. ...
0
votes
0answers
20 views

How to Calculate Pressure From Earth up to Space at Certain Height? [duplicate]

https://en.wikipedia.org/wiki/Vacuum#Measurements_relative_to_1_atm https://en.wikipedia.org/wiki/Pressure_measurement#Thermal_conductivity I wonder if there's a clear equation for this calculation. ...
1
vote
2answers
69 views

How does the decaying orbit of a satellite maintain its orbit as it descends, as opposed to crashing straight back to Earth?

I understand that as a satellite in low-Earth orbit experiences atmospheric drag, it is slowed down. Therefore it no longer has the velocity to maintain its orbit at that point, as per the orbital ...
0
votes
1answer
30 views

Time dialation as observed on earth

Probably a silli q but, I wanted to know if someone has taken a wind up clock into space and observed time dialation? If all our observations are by electronic methods, we dont know if electrics/...
1
vote
2answers
127 views

Why does a light wave fade as it travels through space?

It stands to reason: if it didn't, the entire sky would be covered with stars shining blindingly day and night. But what causes a light wave (or an electromagnetic wave) to fade if there are no ...
1
vote
0answers
34 views

How to determine the position of a planet in our solar system? [duplicate]

I am trying to modelize our galaxy with a simple program. I know how to find the period speed and acceleration of a satellite but I don't know how to get the angle and the current distance between ...
1
vote
0answers
31 views

Space and absolute 0

If two objects like black holes or soild matter are separated by space, let's assume billions and billions of light years. While all other possible energy has left the area, and no new sources. Like ...
0
votes
2answers
41 views

What would all the forces on a space elevator be as it moves up and down?

At the bottom, the acceleration due to gravity would be g. At the top, it would be something like .8g... But would the total acceleration effectively be 0 like on the ISS? How would the acceleration ...
0
votes
3answers
45 views

Looking at past events by observing sky? [duplicate]

Since solar system (and our galaxy) is constantly in motion at a great speed, is it possible that we can look at our own image as it was sometime ago? Since the light of that age takes sometime to ...
1
vote
1answer
117 views

Why did the big bang happen when it did?

Was there time before the big bang? I assume there wasn't, so is it even logical to ask if there was anything before the big bang? If there was time before the beginning of the universe, what happened ...
1
vote
0answers
48 views

Can a spheromak propagate in vacuum?

I recently learned about (and am now fascinated by) spheromaks. I am no expert on plasma physics, but as I understand they are analogous to propagating toroidal vortices (smoke rings), but with plasma ...
0
votes
0answers
26 views

How long does it take for space dust to stop irradiating energy?

I heard that space dust is detectable because it irradiates on the infrared part of the spectrum? Does this happen forever? Won't it stop after some millions of years? Does it have to irradiate until ...
2
votes
0answers
93 views

Can you be your own space suit? [closed]

A few days ago a question was asked on Reddit whether or not a human could survive in space with "just enough" of a spacesuit to plug all the important holes, e.g. a face mask to plug the eyes, ears, ...
0
votes
1answer
75 views

Can more than one photon be in the same space as another photon?

I have heard light described as a particle that travels in a wave. I have heard that waves are unique in that two waves can take up the same space as they are travelling, either through constructive ...
1
vote
1answer
54 views

Effect of redshift on energy conservation [duplicate]

Light coming from galaxies that are going away from us is redshifted. Since the energy of a photon is purely dependent on its frequency one may conclude that the energy of these photons decreases. The ...
3
votes
0answers
75 views

Why do they think WT1190F is low density?

A piece of space debris WT1190F is in the news in part because it has been far from earth (farther than lunar distance) in the past but will re-enter earth's atmosphere in a few weeks. See this note ...
0
votes
2answers
212 views

stopping a rotating mass to achieve linear velocity

So I've been thinking about space, and I had this idea. I haven't found any prior art online for it, and from my limited understanding it seems like a viable idea. So I guess my question is, what am I ...
0
votes
2answers
57 views

Time dilation and reference frame in an orbiting context [closed]

I have looked for other answers, but most confused me more than clarified and did not provide specific calculations. So I am still struggling with this simple question. Consider two persons, $P_a$ ...
3
votes
2answers
63 views

Liquid seperation in space

We know if we take immiscible liquids of different densities then they form different layers on earth. But when we take them to outer space, they form tiny droplets which are energetically most ...
0
votes
4answers
122 views

Why can't a nuclear reactor be used as a rocket motor?

Nuclear fission, and potentially fusion, reactors generate vast amounts of energy, primarily as heat. What stops us from harnessing that energy to propel spacecraft at or above escape velocity from ...