The Science Thread here

Originally posted by Grimpachi
reply to post by fuserleer

 

Thank you for your explanation you have helped me understand this subject better than I ever had and it is something that has puzzled me for years.

Are you sure about that? Even some textbooks don't quite have this topic right so I don't know how people expect to increase their knowledge of science from random ATS members. I suggest listening to Einstein whose theory your question refers to:

physicsandphysicists.blogspot.com...

Einstein's tolerance of E=mc^2 is related to the fact that he never used in his writings the basic equation of relativity theory. However, in 1948 he forcefully warned against the concept of mass increasing with velocity. Unfortunately this warning was ignored. The formula E=mc^2, the concept relativistic mass, and the term rest mass are widely used even in the recent popular science literature, and thus create serious stumbling blocks for beginners in relativity.

As this powerpoint shows, the mass doesn't really increase as Einstein explained (momentum and kinetic energy increase):

physics.wku.edu...

The total energy, E, of a free particle then is the sum of the kinetic energy, K, and the particle’s rest energy, m0c2.
E=K+m0c2

m0 is still the rest mass. It's the kinetic energy that increases, not the rest mass. It's the increase in kinetic energy or momentum that causes additional resistance to acceleration, not additional rest mass.

Some textbooks even say mass increases so I can understand why many people think that, but I think we should heed Einstein's warning against that concept, which many have apparently ignored.

Originally posted by Grimpachi
reply to post by inverslyproportional

 

Thanks you answered a question I was still thinking of a way to ask.

This a little off topic but in the experiment explained where you light the paper in bottle if it was performed and the light produced had no way to escape (theoretical bottle of course that reflected the light 100%) would that mass still be there? Would it still be measurable? Would it settle or be absorbed back into what remained of the paper or would just bounce around infinitely?

Please forgive my questions if they seem dumb I have always loved sci-fi and while it has peaked my curiosity on a multitude of subjects the junk science in much of it has infiltrated my mind as well.

edit on 8-6-2013 by Grimpachi because: (no reason given)

The light would be absorbed by the ashes left from the burned paper, but the heat would escape, as it would heat the gases inside, and transfer to the mirror, and what was on the other side of the mirror.

If you could trap all the gases, and heat and light inside some as of yet, unknown device, then yes, its mass would stay the same.

It is the laws of thermodynamics that actually govern this. Technically, one could take all the heat and light and gases, and ashes, and put them back together and recreate the original paper in its entirety.

Honestly, no we cant do this, theoretically though, there is nothing saying we cant do it one day.

Think of transport at that point, ashes weight nothing, gases are easily compressed, heat can be generated easily.

We could transport 100 of trucks worth of stuff in a van, then reconstitute it on site.

This is the essence of the Star Trek replicator, though I believe they just arrange atoms to reconstitute items.

Very good question though, as if one has little experience with the laws of physics, it would not be possible to even know these things.

I love science, it is so much fun, and allows one to think of things they would consider impossible, only to find ways to make them actually possible through technologies.

One day, maybe in our lives, we will see this in our homes I believe.

Originally posted by ImaFungi

Originally posted by fuserleer
reply to post by ImaFungi

 

Its just space, it isn't empty though.

You will find in there, electrons and photons whizzing by and "matter/anti-matter" pairs that spontaneously appear there annihilate each other giving off gamma rays. Also if they exist will be gravitons.

you cant say its just space, without defining what just space is. Im wondering where there is no electrons, photons, matter/anti matter etc. what is there. what is space???

Honestly, there is no known place devoid of everything. There is no truly empty space. Even in a space cleaned of all matter and energy, there is still at the lowest fundamental level, the quantum foam, and potential energy, which causes particles to just appear and annihilate with antiparticles that also just appear.

There is no actual empty space anywhere, it does not exist, all is quite full of energies and particles, at a fundamental level.

Space is obvious, I dont understand what you dont understand. are you and the wall in the same place? No? Why? Because there is "space" between you?

Space is the seperation between me and you, between here and there, it is a very simple thing to understand, your trying to make it some grand philosophical thing. It is not, it is simply "space" the lack of an object, used to define the seperation of objects, over a space, or unit of measure, as in, the space between us is many miles, the space between the fridge and the TV is 18.24 feet, the space between the floor and ceiling is 9 feet......

Space is easy to see and understand, your making too complicated, when it is the easiest thing in the world to understand.

Originally posted by defcon5
Sure I'll play...
I have a few that have always driven me nuts, and have never had a satisfactory answer to.

These first 3 are sort of interrelated:
1) We are told that being in orbit is being in “free fall”, as your velocity keeps you constantly falling around the planet (fine no problem here). What about something in Geostationary orbit?

What about it? The moon is in a higher orbit than geostationary. Much higher. Orbital mechanics work the same way at different altitudes. The main problem at lower altitudes is more atmospheric friction. This slows down the ISS which is why they have to boost it once in a while.

2) If reentry is from friction caused by slowing down as you enter the atmosphere, is it possible to not have the friction of reentry by slowing down to zero velocity prior to entering into the atmosphere?

Sure, it's theoretically possible. The reason it never happens in practice is there's never enough fuel to decelerate, and we don't really need to slow down first....the atmosphere helps us decelerate on re-entry.

3) If none of those things work, then how is the supposed “space elevator” going to work with part of its “cable” constantly in reentry?

I can't say the space elevator will work. But it won't have any problems with re-entry. There is no material that will work for the cable yet known, and other problems.

4) According to thermodynamics we can never have any zero point energy or create more energy then we put into something. So we can never have perpetual motion. Yet when a satellite tumbles it keeps tumbling almost indefinitely until another force acts on it in the opposite direction, or over a long time the slight amount of friction in space stops it.
With the above in mind, shouldn't it be possible to make a simple generator whose armature spins indefinitely within a coil as long as it's in the same type of nearly frictionless environment?

We have generators that use something along these lines if you want to stretch a point...they generate energy from ocean tides. That's possible. And you can extract energy from orbits and rotational motions like that but of course when you do, the orbit decays or the rotation slows down according to how much energy you extract. Since the Earth is so big, using tidal power won't slow it down that much.

Originally posted by defcon5
Sure I'll play...
I have a few that have always driven me nuts, and have never had a satisfactory answer to.

These first 3 are sort of interrelated:
1) We are told that being in orbit is being in “free fall”, as your velocity keeps you constantly falling around the planet (fine no problem here). What about something in Geostationary orbit?
2) If reentry is from friction caused by slowing down as you enter the atmosphere, is it possible to not have the friction of reentry by slowing down to zero velocity prior to entering into the atmosphere?
3) If none of those things work, then how is the supposed “space elevator” going to work with part of its “cable” constantly in reentry?

4) According to thermodynamics we can never have any zero point energy or create more energy then we put into something. So we can never have perpetual motion. Yet when a satellite tumbles it keeps tumbling almost indefinitely until another force acts on it in the opposite direction, or over a long time the slight amount of friction in space stops it.
With the above in mind, shouldn't it be possible to make a simple generator whose armature spins indefinitely within a coil as long as it's in the same type of nearly frictionless environment?

First off, very nice questions, you already understand the answers, your just not putting it together.

If I orbit at 100 miles I have to go at 17,000 MPH to reach "escape velocity" so the earth gravity cant pull me back down, as I have escaped its hold through speed.

I was in artillery, so this is easy to explain for me, it all goes back to newton. He asked, if I shoot a connon with x energy the cannon ball will go x disatnce, but if I add x to it again it will go further, so I should be able to shoot it hard enough to make it go all the way around and come back to its point of origin. This is what orbit is.

It just takes approx. 17,000 MPH to achieve this, in a vacuum, as atmosphere will slow it and make it fall back before it reachs the origninal source of its launch.

If you had a space ship, and it had super powered engines, that never ran out of fuel, you could come back into the atmosphere at any speed you wanted, say 1mph, and there would be no burning fireball.

We just find it alot easier to burn in and let the atmosphere slow us with friction from orbital speeds, above 17k MPH to a more useful, in atmosphere speed of several hundred MPH. As it would take a much larger initial launch vehicle to take enough fuel to burn the engines to stop you to 0 MPH, and then keep burning to bring you down under power slowly.

Geosync orbit is easy. At 100 miles it takes 17,000 MPH to orbit, at 22,000 miles out, the height of geosync orbit, it is still 17,000 MPH, your just so high up, that you dont go around the earth, you match its rotational speed with the speed of your orbit. So your still in orbit, just orbiting the same speed as the world spins.

Much as the moon spins at the exact same speed it orbits, so the same side always faces us.

The space elevator, would be 22,000 miles long, connected to a geosync satellite, so it would just basically be going straight up to a satellite that stays in the same spot. Using inertia to keep the tether, thats what you would call the elevator, a tether, tight so that it doesnt go slack and pull the whole thing down when somthing climbs up it.

There is nothing but a steady change from ground temp to super cold, almost absolute zero in space, so it is no problem really, we already operate in that environment all the time with the space shuttles before their retirement, and the ISS, and satellites.

It would just take alot less fuel, as the act of climbing the tether to the end of the 22,000 miles length would get you the 17,000 MPH needed to orbit. You could just step off and be in geosync orbit once you climbed it.

reply to post by Arbitrageur


No I understood after their explanations it was the misconception you are speaking about that had me bewildered for so long. As I stated before I had always equated an increase in mass with an increase in size however now I understand the mass is energy I believe in the form of kinetic.

I understand better with the addition of your explanation although I was almost there already even if I am not sure how I made those connections but yeah I am fairy sure I understand I just will not be trying to teach this to anyone else.

I am in a learning mood today or else this all would have gone over my head.

Originally posted by inverslyproportional

Originally posted by defcon5

It just takes approx. 17,000 MPH to achieve this, in a vacuum, as atmosphere will slow it and make it fall back before it reachs the origninal source of its launch.

Interesting fact about 17,000mph velocity to escape the earths gravity.

Why is there no Hydrogen or Helium in the atmosphere?

Because the sum their oscillational movement, at their frequency at 0 kelvin, and the small rest mass, allows that to be greater than 17,000 mph.

If you were to add all the distances of those oscillations up and represent it in MPH form, it exceeds it.
Thus, over time, they escape earths gravity.

Science question after this biology question.....what good do yellow jacket wasps serve? I don't guess they'd eat skeeters, would they......

Science....in our 3-D physical reality...are we given input via a freqency to our conciousness....like maybe one could "hear" it.....stay with me now......that supply's our awareness?
In the 70's once while intoxicated in the Air Force, ....I felt I was being talked to by the external, God, and my hearing "base line" sound,... or the background tone of my hearing.....went from normal, what would describe as digital input at 16,000 Htz, ....went slowly down to zero........I was feeling no other sensation of difference......stayed there for three seconds maybe then climbed back up.....

As if God was showing me "my connection" to reality and awareness was controlled by Him, but not to worry, he wouldn't leave it shut off.....

reply to post by inverslyproportional

Excellent answer...
One more thing though. Going up the tether is still going to require enough energy to reach 17K mph, and when coming back down you'd have to shed it. So wouldn't it take increasing amounts of energy to climb the higher you got as you would have to speed up, and wouldn't it still burn in shedding its 17K mph speed on entry? How about the tether itself, is it actually moving at 0 or at 17K mph?

Originally posted by Grimpachi
reply to post by Arbitrageur

 

No I understood after their explanations....

There is a big difference between

E=mc²

and

E=K + m0c²

The first one is really a simplified form of the second where the mass is at rest. So,explanations using an equation where the motion term K was zeroed out, to explain what happens when objects are in motion is probably not a very good explanation.

Excellent answers as well.

Originally posted by Arbitrageur
We have generators that use something along these lines if you want to stretch a point...they generate energy from ocean tides. That's possible. And you can extract energy from orbits and rotational motions like that but of course when you do, the orbit decays or the rotation slows down according to how much energy you extract. Since the Earth is so big, using tidal power won't slow it down that much.

The generators you are talking about are converting energy from another force, like waves.
A satellite that is spinning has been acted on by a force once, and there is nothing to essentially ever slow that rotation. So this by itself seems to defy thermodynamics. Its a small energy input for an almost continual output (the rotation). Unless, I suppose, that the rotation is actually potential energy that just has not been changed by an outside force (friction), which would make sense. So in essence the spinning satellite then is like a capacitor that is storing a charge?

How do trees get thicker as they grow if the outer layer of bark ( which is pretty think) falls off each year eg the "sock" that can be seen on say a spotted gum or the thick bark layer of an iron bark?

1. If the Earth and the rest of the solar system is speeding through space at 2.7 million MPH (according to: Source), how come we don't notice it?

Everything appears stationary. Is the rest of space moving away from us at the same velocity in the same direction? Are the distances so vast that it'll take forever to notice a perceived change. Is it because the visibile light we're seeing from other stars is so old that it stays the same? Mind boggling

Originally posted by defcon5
reply to post by inverslyproportional

 

Excellent answer...

One more thing though. Going up the tether is still going to require enough energy to reach 17K mph, and when coming back down you'd have to shed it. So wouldn't it take increasing amounts of energy to climb the higher you got as you would have to speed up, and wouldn't it still burn in shedding its 17K mph speed on entry? How about the tether itself, is it actually moving at 0 or at 17K mph?

Damn, you guys are good, Tough questions all around.

The thing is, you would not really notice the gain or loss of the speed, as it would come and go so slowly over such a long distance. it will take a long time to climb 22,000 miles straight up, maybe even a few days, so it would not be like taking off in a car or braking in a car even, it will be slowly and gradually over time both up and down the tether.

It would not really reguire greater amounts of energy to achieve extra speeds, as this is not even close to relativistic speeds, so the amount of extra energy would not be that great, though it is still measurable and real, it is very small in the human experience of the world.

There would be no burning, as one would not be going the 17,000 MPH by the time they hit the atmosphere, as they would have shed speed for the length of 21,940 miles approx before they started hitting any real amounts of gas atoms from the atmosphere. They would already be back down to a slower speed.

Also though, they wouldnt really have any "speed" relative to the atmosphere, as they are not moving horizontally, they are only moving in the verticle axis, so they would only be going about 20 MPH no matter what, just up or down, depending on if they were coming or going from the satellite.

Think of it like this, a plane has to be going around 80 MPH to fly off the ground, depending on the type this varies greatly, so to get to about 400 feet they have to be travelling around 120 MPH or so, but i can stand perfectly still in a building at that height, with no speed.

This is the difference here, space ships have to have powered flight to escape the gravity, with the tether, we are cheating and basically just going up an elevator, not "flying".

However, the speed comes from the fact we are basically a sinker on a rope, and the earths rotation is what is giving us speed.

Just take a fishing sinker, and put it on a fishing line. Hold the line at your waste, and start spinning in place, let the line out slowly, and you can see this exact effect happening, it is inertia that is doing all the work of holding up the tether, we are just climbing up and down the length of the string.

Now you will notice, that the sinker is staying straight relative to you, though it is moving when compared to the space around you.

From your perspective, the sinker is not moving, but the fact it is flying out, proves that it is in fact moving fast enough to overcome gravity.

This is the way the elevator works.

Now imagine your the earth, the guys traversing the elevator would not be moving in any direction but farther away from you, always right in front. So there is not horizontal speed relative to the surface, just verticle, as they climb up it, but compared to everything around them, they would be travelling at the requisite 17,000 MPH to achieve geosync orbit.

Hope this helped, if too vague, or not in depth enough on certain aspects, I can refer you to a video that will better explain it, I am just not a word smith.

reply to post by Arbitrageur


Well rest mass only exists, when you can measure the mass of an object in the same frame of reference as your self right?

You seem to be offended because you perceive the definition of mass having to do with the quantity of particles. Noone is saying when you accelerate a 1 kg lead ball that there are more quantities of particles added to it to increase its mass. It is the fact that if you were to measure the mass of a 1 kg lead ball that was accelerated it would have the affect of having more mass.

do you know what the significance of c^2 in the equation is? because that being present right away signifies that mass is not equal to energy. Mass x the speed of light squared is that masses energy. But how do you find the mass of an object? And how do you find the mass of an object that is accelerated to a significant degree more then your relatively stationary frame of reference?

If there was 1 particle stationary in a very large vacuum chamber. and the particle had mass X, and then (somehow hypothetically) the particle was accelerated to a much great velocity, its mass would still be X right? But it would have more energy then before. But multiplying stationary X by c^2, and great velocity X by c^2 would yield the same product.

Originally posted by defcon5
The generators you are talking about are converting energy from another force, like waves.

I wasn't talking about waves. I was talking about generators that use the tides. Where does tidal energy come from? It's a consequence of the orbit of the moon and the rotation of the Earth. The Earth's rotation is slowing down as a result of the Earth-moon interaction including the tides. So the source is really what you mentioned, a satellite in orbit, where the satellite is the moon. This is a real-life application of extracting energy from an orbiting satellite, the moon:

Tidal energy generator to be built in Northern Ireland

A satellite that is spinning has been acted on by a force once, and there is nothing to essentially ever slow that rotation. So this by itself seems to defy thermodynamics. Its a small energy input for an almost continual output (the rotation). Unless, I suppose, that the rotation is actually potential energy that just has not been changed by an outside force (friction), which would make sense. So in essence the spinning satellite then is like a capacitor that is storing a charge?

I think rotation may last longer than orbits, but both slow down. The friction is very low so they don't slow down very much. There is really no violation of thermodynamics to say when friction is low the frictional effects are reduced. But they never really go to zero, since even deep space has a hydrogen atom per cubic meter and it's denser near massive bodies due to gravity, and this will slow down orbits and rotations, though very little in some cases.

Yes you can think of a satellite like a capacitor storing a charge I suppose.

reply to post by inverslyproportional


You say its me over thinking it, I will remain in belief it is you who is under thinking it.

Everything is moving right, all the atoms, the solar system, the galaxy, the planet, our atoms etc. What are they moving in relation to? Is there an absolute empty space? You are saying there are little holes in everything, and that comes in contact with new quantities of nothingness all the time.That is my problem I guess, quantifying space, I cant imagine an infinite quantity of nothing, on which quantized particles of matter pass of, or exist in, or on.

Originally posted by majesticgent
1. If the Earth and the rest of the solar system is speeding through space at 2.7 million MPH (according to: Source), how come we don't notice it?

Everything appears stationary. Is the rest of space moving away from us at the same velocity in the same direction? Are the distances so vast that it'll take forever to notice a perceived change. Is it because the visibile light we're seeing from other stars is so old that it stays the same? Mind boggling

edit on 8-6-2013 by majesticgent because: (no reason given)

You already gave yourself that answer, it is all too big, so we little ants dont notice.

The galaxy is large, that if you lived for a million years, you would not even notice a change in the sky at all. Only instrumentation is accurate enough to notice this small variance.

It really is so that we are mere atoms on a piece of sand, on one of the many beachs of this world, maybe that still makes us too big though.

reply to post by Arbitrageur


Eh…you lost me there. Let me explain better what I was trying to convey.

I now understand what they were saying however I would not be able to teach it. My misconception was thinking exactly what you were saying most people misunderstand which was that the actual mass would increase.

For me I am participating in this thread simply to better my understanding on subjects and nothing more.

Trust me I will not be trying to teach or debate this with anyone it is out my own selfish desire to understand certain concepts and sciences as long as it works in my head I am fine with that.

Originally posted by inverslyproportional
Think of it like this, a plane has to be going around 80 MPH to fly off the ground, depending on the type this varies greatly, so to get to about 400 feet they have to be travelling around 120 MPH or so, but i can stand perfectly still in a building at that height, with no speed.

So the act of actually flying, overcoming drag, etc.., is where the extra energy is going then? A man walking or riding an elevator uses less energy to gain altitude in a building. An aircraft uses more because of the other forces it has to overcome to maintain forward momentum and lift. So the man walking up stairs is simply a more effective way to do the same thing, using less energy.
Now wouldn't it be possible to build a balloon that would be able to actually fly into space as long as it could handle the pressure changes? The Earth is constantly losing hydrogen into space all the time. There must be some little factor I am missing here still, because a slowly accelerating balloon should be able to do the same thing that the elevator is, yet as far as I know they cannot. It would obviously be much more efficient than a rocket or aircraft.