What Will Happen to a Fan in Space?

[jared69sib]

There is essentially no drag on spacecraft once they get a few hundred miles from Earth.

If that was true, the why would our ability to accelerate be limited? Surely, we could design a burst method to constantly accelerate no?

 

[jared69sib]

There is already a hypothetical engine design which does this, a Bussard Ramjet: http://en.wikipedia.org/wiki/Bussard_ramjet

Yea, I briefly read about this. I guess that is basically where my idea came from...the designs I had in mind though are quite different.

 

[JaredJames]

Jared, your last post is based on a severly flawed understanding of relativity.

This thread is not the place for that discussion.

 

[jared69sib]

Space is a NEAR perfect vacuum. There are most definitely particles in space, however the density of the particles is extremely low. So low that once you get beyond the Earth's atmosphere it's pefectly acceptable to say that there is no drag for almost all purposes other than scientific experiments.

Using a fan as a propulsion method would never work, as even with a large funnel gathering the particles in front and compressing them at the fan would still result in far too small a quantity to perform any useful armount of work. Also, you cannot get to the speed of light Jared. Ever.

We can't reach the speed of light YET! But it can be done. At least theoretically... The biggest concern would be having a medium that would not be destroyed at that velocity or putting in a system to provide temperature control, etc. The only thing stopping us from reaching the speed of light is G-Force, and a large enough fuel source. Wouldn't you agree?

 

[russ_watters]

If that was true, the why would our ability to accelerate be limited? Surely, we could design a burst method to constantly increase or acceleration no?

Our ability to accelerate is limited only by the fuel we can carry on our rockets.

We can't reach the speed of light YET! But it can be done. At least theoretically... The biggest concern would be having a medium that would not be destroyed at that velocity or putting in a system to provide temperature control, etc. The only thing stopping us from reaching the speed of light is G-Force, and a large enough fuel source. Wouldn't you agree?

No, reaching light speed is forbidden by scientific theory.

 

[Drakkith]

We can't reach the speed of light YET! But it can be done. At least theoretically... The biggest concern would be having a medium that would not be destroyed at that velocity or putting in a system to provide temperature control, etc. The only thing stopping us from reaching the speed of light is G-Force, and a large enough fuel source. Wouldn't you agree?

Nope. As your velocity increases, it takes more and more energy to accelerate. It takes an infinite amount of energy to make something with mass reach the speed of light. It cannot be done, not even theoretically.

 

[jared69sib]

Our ability to accelerate is limited only by the fuel we can carry on our rockets. No, reaching light speed is forbidden by scientific theory.

Please excuse my ignorance, but why is it forbidden? I am sure it is based on a equation, but just have to ask.

 

[jared69sib]

Nope. As your velocity increases, it takes more and more energy to accelerate. It takes an infinite amount of energy to make something with mass reach the speed of light. It cannot be done, not even theoretically.

But let's imagine an unlimited fuel source for a moment...

Maybe we could send some unmanned spacecraft ahead with extra fuel, since G-Force is not a factor...

Or maybe we can abandon rocket fuel as a source once we exit the atmosphere, and use something lighter like compressed hydrogen some how... (I'm still thinking about that fan, but so reluctant to say it).


Or beam lasers at the space craft...

 

[russ_watters]

Please excuse my ignorance, but why is it forbidden? I am sure it is based on a equation, but just have to ask.

Einstein's theory of Special Relativity states that to any observer, the speed of light is always the same. In other words, no matter how fast you think you're going or how long you're accelerating, you'll always be zero with respect to the speed of light. So even when chasing a beam of light, it'll always move away from you at the speed of light.

In a rocket, it means that to an outside observer your acceleration will continuously decrease and you'll get closer and closer to the speed of light without ever reaching it while to you, in your spacecraft , you'll always feel the same acceleration.

http://en.wikipedia.org/wiki/Special_relativity

 

[JaredJames]

An unlimited source of fuel doesn't exist. There is no such thing as "infinite energy". It is this that makes attaining light speed impossible.

 

[jared69sib]

Nope. As your velocity increases, it takes more and more energy to accelerate. It takes an infinite amount of energy to make something with mass reach the speed of light. It cannot be done, not even theoretically.

To me it seems that the amount of energy required cannot be infinite. A simple law in calculus tells you that anything finite or that can be defined must contain all finite parts... Not the exact wording, but you get the gist...

If something like the speed of light can be defined as 186,000 miles/sec, then it is a finite number correct? It is not an infinite speed... Unless however that little bit of drag that doesn't make a difference now does in this situation... (I think it does)... So the acknowledgment of drag is important... so even the light must succumb to drag...otherwise there wouldn't be any limit... and light is the fastest thing we know of correct?

I think drag should be considered for us to conquer this problem.

What do you guys think of graphene? Electricity can travel at 200,000 cm2 V−1s−1 and 40,000 cm2 V−1s−1 based on some limiting factors. I'm guessing s stands for seconds right? It's conductivity slows down quickly, but I remember hearing something about it approaching light speed...******Light speed is 186,000 miles/sec, not hour. I changed it above. TYPO! Brain glitch! LOL.

 

[jared69sib]

Einstein's theory of Special Relativity states that to any observer, the speed of light is always the same. In other words, no matter how fast you think you're going or how long you're accelerating, you'll always be zero with respect to the speed of light. So even when chasing a beam of light, it'll always move away from you at the speed of light.

In a rocket, it means that to an outside observer your acceleration will continuously decrease and you'll get closer and closer to the speed of light without ever reaching it while to you, in your spacecraft , you'll always feel the same acceleration.

http://en.wikipedia.org/wiki/Special_relativity

I think we just can't go fast enough yet...

 

[jared69sib]

An unlimited source of fuel doesn't exist. There is no such thing as "infinite energy". It is this that makes attaining light speed impossible.

So that supports my theory that the fuel source to achieve light speed is finite.

Thanks for humoring me everybody. LOL. I still have a lot to learn, but there are all some of the very basic and primitive ideas shooting around my noggin. Einstein was a bad-*** rebel in his day right? We need a new rebel! :)

 

[russ_watters]

I think we just can't go fast enough yet...

Well, you're wrong, plain and simple. And your speculations above are wrong too (essentially everything in your previous post was wrong, including the speed of light). There is a lot that you don't know about how the universe works, but just because you don't know, that doesn't mean others don't know and it doesn't make your speculations reasonable, it makes them foolish. More to the point, this forum is for learning real science, not for idle speculation. Please keep that in mind.

 

[cdotter]

To me it seems that the amount of energy required cannot be infinite. A simple law in calculus tells you that anything finite or that can be defined must contain all finite parts... Not the exact wording, but you get the gist...

Math is a human construct and nature is not.

 

[JaredJames]

So that supports my theory that the fuel source to achieve light speed is finite.

No, it says the exact opposite.

Thanks for humoring me everybody. LOL. I still have a lot to learn, but there are all some of the very basic and primitive ideas shooting around my noggin. Einstein was a bad-*** rebel in his day right? We need a new rebel! :)

With your current knowledge and understanding, it certainly won't be you.

 

[jared69sib]

Well, you're wrong, plain and simple. And your speculations above are wrong too (essentially everything in your previous post was wrong, including the speed of light). There is a lot that you don't know about how the universe works, but just because you don't know, that doesn't mean others don't know and it doesn't make your speculations reasonable, it makes them foolish. More to the point, this forum is for learning real science, not for idle speculation. Please keep that in mind.

Well, I am trying to learn. You don't need to be so blunt. And I fixed my little typo above about the speed of light...fyi.

 

[jared69sib]

No, it says the exact opposite.


With your current knowledge and understanding, it certainly won't be you.

Your comment was also not necessary.

 

[jared69sib]

If your goal doesn't include motivating a young or new enthusiast, then what are you doing on this forum. I certainly wouldn't appreciate you talking to my son that way...

 

[JaredJames]

You are claiming that published science is wrong. Read the materials and learn from it. I assure you, all the stuff you're thinking about it has already gone through someones mind.

Next time, ask why something is what it is and don't simply tell us it is wrong. Then you'll avoid such reactions.

And no, my goal isn't to motivate. It is to help educate others and learn more myself.

Anyone who wants to be overly speculative and make ridiculous claims doesn't belong here. Those are the rules.

 

[jared69sib]

You are claiming that published science is wrong. Read the materials and learn from it. I assure you, all the stuff you're thinking about it has already gone through someones mind.

Next time, ask why something is what it is and don't simply tell us it is wrong. Then you'll avoid such reactions.

And no, my goal isn't to motivate. It is to help educate others and learn more myself.

Anyone who wants to be overly speculative and make ridiculous claims doesn't belong here. Those are the rules.

I'm sorry if any of you felt I was saying you're wrong. That is why I felt inclined to tell you that I acknowledge the fact I'm a newb. I'm just trying to understand myself, and at one point I did ask for an example equation to explain a certain part of this convo...

Technically, I am following the rules since I am keeping things within my own education level and understanding. I start college to get a degree in Engineering Science this month, and I was just trying to dive in before it all starts. I never had an interest in Physics until I completed Calculus II, but now I am really interested.

In the future, I will try to hold back my spontaneous thoughts. I realize they can be ridiculous...a lot of people think I'm an idiot just based on my personality, but when it comes to exam time I do really well. I just don't want to accept some things the way they are. You all should understand that. HOW AWESOME WOULD IT BE TO VISIT ANOTHER GALAXY!? I'd love to see how life has evolved somewhere else. It's a shame we can't live longer...yet... lol

 

[jared69sib]

http://en.wikipedia.org/wiki/Faster-than-light"

 

[jared69sib]

Thus, because the pilot cannot place infrastructure ahead of the bubble while "in transit", the bubble cannot be used for the first trip to a distant star. In other words, to travel to Vega (which is 25 light-years from the Earth) one first has to arrange everything so that the bubble moving toward Vega with a superluminal velocity would appear and these arrangements will always take more than 25 years.[5]

Cool stuff.

http://en.wikipedia.org/wiki/Alcubierre_drive"

 

[JaredJames]

Discussion of speculative material is not allowed.

FTL travel isn't possible. Period.

Those models, by their own admission are all speculative.

What is it you want us to look at in the FTL wiki page? Rgardless, I would recommend you check the references. It will tell you whether or not what is written is published theory or purely speculative.

EDIT: Read the piece on travel in your faster than light wiki page. It tells you it isn't possible.

 

[Drakkith]

Let's say that you are traveling at 99% the speed of light relative to an observer. If you expend the same amount of fuel that got you to 99% the speed of light, you would only accelerate a small amount relative to that observer, and would be going a little bit over 99%. And if you do it again you get even less velocity for the fuel you expend. This continues to happen as you get closer to the speed of light, making it so that you can never reach it, only get very close.

Actually, look up the Large Hadron Collider. They accelerate protons upwards of 99.9999% the speed of light. As the protons gain speed, it takes more and more energy to accelerate them the same amount.

 

[martix]

I calculated somewhere that those 99.9999% the speed of light(or whatever figure I used then) was equal to just 10km/s shy of C. Imagine what the world would look like while zooming around at that speed(my idea is highly distorted FoV and copious amounts of blue/redshifted images).

Anyway I was wondering, since the average density of outer space certainly is >0, what acceleration could such a fan achieve(outside of the gravitational influence of any bodies. :)

 

[Drakkith]

I calculated somewhere that those 99.9999% the speed of light(or whatever figure I used then) was equal to just 10km/s shy of C. Imagine what the world would look like while zooming around at that speed(my idea is highly distorted FoV and copious amounts of blue/redshifted images).

Anyway I was wondering, since the average density of outer space certainly is >0, what acceleration could such a fan achieve(outside of the gravitational influence of any bodies. :)

This depends on the density of matter in space where your at, the size and mass of the fan and vehicle, and several other variables. Short answer, very very very low acceleration.

 

[russ_watters]

The fan would still need to have the pitch and rpm required to push those particles instead of being pushed by them (becoming a turbine). That would be a pretty tall order!

 

[Lsos]

jared69sib, your model of the universe is too simple to try to figure out what happens at close to the speed of light. You're thinking...well, 186,000 miles/second, if we accelerate long enough we will reach it.
No. The actual formulas for speed and acceleration are more complicated that simple kinematic equations.

In everyday life they do just fine, but when you start getting to very high speeds (fractions of the speed of light), these formulas cannot cope. For example, acceleration is distance/ time^2. However, as you go faster, the distance AND the time actually warp and stretch. As you get closer to the speed of light, the space and time will stretch away from you so that you will NEVER reach the speed of light. Not if you convert all the mass in the universe into energy and put it into one atom. Not even if god himself tried to accelerate that atom, would He be able to make it go the speed of light.

Even if we convert to Hinduism and employ many gods to accelerate that atom, they might be able to add a few extra 9s to the 99.99999999999999999999999% of the speed of light, but NEVER actually reach it.

 

[martix]

Now there's a thought. Considering the best estimate of how much "STUFF"( [dark] energy, matter, whatever else you can think of) there is in the universe, just how many additional 9's could we add behind a single proton?

But yea, there's a reason why classical/Newtonian mechanics is a separate entity from relativistic mechanics. :)
Just as there is a reason why relativistic mechanics is separate from quantum mechanics:
They don't fit together at all.
(not yet anyway)