Vacuum Space

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“A vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure.”



Operating in a vacuum can have some benefits but what if you had a vacuum of energy and matter so that there was nothing, no background radiation or anything? Would that be useful for anything or has something like that been used?

 
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transportation.

 
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Originally posted by slasher:

transportation.

indeed , New York to LA in 10 min :D

we should build a tunnel like that, we have the technology

 
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Operating in a vacuum can have some benefits but what if you had a vacuum of energy and matter so that there was nothing, no background radiation or anything? Would that be useful for anything or has something like that been used?

I think the sensors that they have deep within mountains to look for neutrinos have to operate within a perfect vacuum. No background radiation or even stray cosmic waves I don’t think.

we should build a tunnel like that, we have the technology

Would it not cost a ridiculous amount to create and maintain a vacuum in a tunnel that length that’s big enough to fit a train down?

 
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perfect vacuum

Impossible.

Anyways, neutrino telescopes are typically filled with water.

 
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Would it not cost a ridiculous amount to create and maintain a vacuum in a tunnel that length that’s big enough to fit a train down?

Well if it only took 10 mins we wouldn’t need a whole train.

 
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If we are taling about anti-matter, that stuff costs 10 billion a tablespoon for the materials.

edit: sorry, I was way off. with an estimated cost of $62.5 trillion per milligram, it is the most costly thing in the universe.

 
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Who would need to buy anti-matter?

 
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You’d need to pull 4+ Gs all the way to go 4000km in 10 minutes. That is, assuming you wanted to actually stop when you’re there, rather than keep going.

 
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antimatter would be a great fuel source, it is really fast, but cannot be used because of its scarcity.

 
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Originally posted by Jabor:

You’d need to pull 4+ Gs all the way to go 4000km in 10 minutes. That is, assuming you wanted to actually stop when you’re there, rather than keep going.

While this would be really annoying, it isn’t much of a difference from really fast roller coasters.

 
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You know why?

Because all antimatter on Earth is stuff that scientists have produced on Earth. And we all know our thermodynamics, right? Producing antimatter, and then converting it into energy and using it is more expensive than just using the energy in the first place.

While this would be really annoying, it isn’t much of a difference from really fast roller coasters.

How much of the civilian population do you think could handle 10 minutes of constant 4.5G acceleration, twice a day, five days a week?

 
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How much of the civilian population do you think could handle 10 minutes of constant 4.5G acceleration, twice a day, five days a week?

I’m sure those willing to pay for it wouldn’t mind.

 
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Which means the question is, how many people would be willing to pay for it?

Not enough to make it a worthwhile investment, by any means.

 
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antimatter would be a great fuel source, it is really fast, but cannot be used because of its scarcity.

So your saying someone has designed some sort of anti-matter engine or do i just put it in my gas tank?

 
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While we’re talking about stuff that’ll never happen, we should think bigger! What we need to do is dig a hole through the center of the Earth, completely depressurize it, and then let people in pressure suits dive to China. I never got past constant acceleration in physics and I don’t feel like deriving the higher order equation now, but I’d guess it wouldn’t take more than five hours, a day max.

 
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cept once you reach china you will start falling back toward America. Actually digging a hole straight down from America would probably land you in the pacific ocean some where.

 
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Originally posted by Einar:

While we’re talking about stuff that’ll never happen, we should think bigger! What we need to do is dig a hole through the center of the Earth, completely depressurize it, and then let people in pressure suits dive to China. I never got past constant acceleration in physics and I don’t feel like deriving the higher order equation now, but I’d guess it wouldn’t take more than five hours, a day max.

If you dig a hole straight through the Earth in Massachusetts, you would end up in the ocean southwest of Australia. That doesn’t sound terribly practical. Most of North America will end up with a hole around that area.

See where you end up.

 
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cept once you reach china you will start falling back toward America.

Which is why you grab onto the pressure lock there and pull yourself out, silly!

 
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How long would it take to ‘fall’ through the earth? Also, you would reach terminal velocity at some point and I doubt you would even reach close to the other side!

 
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How long would it take to ‘fall’ through the earth? Also, you would reach terminal velocity at some point and I doubt you would even reach close to the other side!

Its a vacuum so there is no friction from air

 
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To elaborate, there is only a “terminal velocity” if there is air resisting your fall. We’d evacuate the air in that hole, so there wouldn’t be a problem with that.

Also! How long would it take?

According to the great Googlies, the diameter of the Earth is 12756200 m. Gravity, as we all know, is 9.8 m/s^2. Of course, as we descend into the Earth, the force of gravity will gradually decrease until it reaches zero at the core, and then begin increasing again in the opposite direction. Difficult to handle, no?

Fortunately, there’s a trick we can use. If the gravity goes from 9.8 to zero and does so uniformly (which indeed it does), then you can simplify the model by saying that, on average, you are accelerating at a constant 4.9 m/s^2 until you get to the center of the Earth, at which point you you are accelerating at the same rate in the opposite direction.

This simplification makes things trivial. The position function for constant acceleration is s1 = s0 + vt + 1/2at^2, where s1 is your ending position, s0 is your beginning position, v is velocity, a is acceleration, and t is time. We obviously don’t know v, but we don’t need to; when you have constant acceleration, v = at.

s0 is going to be 0, but to where do we measure? Well, we know that from 0 to halfway inside the Earth we can pretend the acceleration is constant, so we’ll do that since it makes life easiest. Thus, s1 will be 6378100 meters.

So, we have 6378100 = (at)t^2 + 1/2at^2 , or 6378100 = 1.5 * 4.9 * t^2. We will of course need to double the result to account for the second leg of the journey.

If you do the math, that ends up being about 1800 seconds total, or half an hour. Not even long enough to get through your normal in-flight safety presentation, much less eat those peanuts.

 
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Well I just assumed it wasn’t a vacuum tube! I still don’t think you could fall all the way through the earth.

 
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Well I just assumed it wasn’t a vacuum tube!

The original stipulation was that it was completely depressurized.

I still don’t think you could fall all the way through the earth.

Why not? No friction, so your energy wouldn’t change. Same distance from the centre of Earth at each end.

 
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Suppose there was a strong magnetic field halfway through that could slow you down… or speed you up and blast you into space!



Einar: Ha pretty neat. I wonder what it would feel like because when you fall you ‘feel’ weightless but your weight is constantly changing over that 30 minutes