Grandiose free transportation

Well free in that it does not take energy to get from point A to point B.
Drill a bigass hole, one version has it going straight through the
planet, suck out the air, then have tunnels with permenant magnets
inside, the car would be a cylinder with magnetic fields in repelling
mode to keep the cars away from the walls, and let it drop.
First it accelerates at one G reaching a speed of 11 Km/S at the center
of the earth, then starts decelerating till it gets to the other end
at which time it is going zero Kps and the magnets simply reverse
polarity and it is grabbed and held in place, doors open, people
and cargo get out, it reloads for the journey back.
Average about 5 1/2 Km/second or roughly 45 minutes to go from
one end of the earth to the other. Obviously slightly impractical but
there are versions more realistic where you make a tunnel but don't go
straight down but angle off to connect two points widely separated.
This time you make the tunnel curved so as to always be accelerating
and decelerating but not making it so deep as to be impossible to
deal with the forces inside the earth. The tunnel is still in vacuum
but the car is lying on its side taking off Luge-wise but held away
from the walls by permenant magnets like a maglev train.
It would not go as fast but it would not use fossil or any other kind
of fuel nor emit greenhouse gasses. You would connect two points of
the earth far away and get transport with no fuel needed.

Originally posted by sonhouse
Well free in that it does not take energy to get from point A to point B.
Drill a bigass hole, one version has it going straight through the
planet, suck out the air, then have tunnels with permenant magnets
inside, the car would be a cylinder with magnetic fields in repelling
mode to keep the cars away from the walls, and let it drop.
First it acceler ...[text shortened]... ses. You would connect two points of
the earth far away and get transport with no fuel needed.

You can't change the polarity of a permanent magnet, can you?

Originally posted by sonhouse
Well free in that it does not take energy to get from point A to point B.
Drill a bigass hole, one version has it going straight through the
planet, suck out the air, then have tunnels with permenant magnets
inside, the car would be a cylinder with magnetic fields in repelling
mode to keep the cars away from the walls, and let it drop.
First it acceler ...[text shortened]... ses. You would connect two points of
the earth far away and get transport with no fuel needed.

It'll never happen. For one upfront cost and difficulty.

At a depth of 5km (around the level of extremely deep mines) you have to cope with temperatures of 70C and huge pressures , this increases as you go deeper. You would be wise to do some maths (segment and chord lengths) to see just how deep you'd have to go to join two points any distance apart.

Originally posted by sonhouse
Well free in that it does not take energy to get from point A to point B.
Drill a bigass hole, one version has it going straight through the
planet, suck out the air, then have tunnels with permenant magnets
inside, the car would be a cylinder with magnetic fields in repelling
mode to keep the cars away from the walls, and let it drop.
First it acceler ...[text shortened]... ses. You would connect two points of
the earth far away and get transport with no fuel needed.

What would be the energy usage required to build this energy free system? Even if possible, it would take years (decades?) to build and use an enormous amount of resources, so if you started today, how long before the energy used to build would be paid back in energy saved from actually using the system?

Originally posted by AThousandYoung
You can't change the polarity of a permanent magnet, can you?

Well it doesn't exactly have to be a permanent magnet but yes you
can, there are lifting magnets now that can be switched in and out
very easily even though they can lift 400 pounds each. Its how its
constructed inside, actuators lift the actual magnet, once you do that
its no big deal to just turn it around. The way it works is by a cam
that separates the magnet from the outer magnetic conducting
metal layer.
It can also be a superconducting magnet, switched electrically,
they can be enormously powerful and require no energy for the
current, only for cooling.

Originally posted by XanthosNZ
It'll never happen. For one upfront cost and difficulty.

At a depth of 5km (around the level of extremely deep mines) you have to cope with temperatures of 70C and huge pressures , this increases as you go deeper. You would be wise to do some maths (segment and chord lengths) to see just how deep you'd have to go to join two points any distance apart.

All the math has already been done, I did not originate this idea.
But you are right in the heat at those depths of course but reflective
coatings will help there. One of my semiconductor manufacturing
machines, called an advanced oxide etcher uses oil to heat the
working chamber up to 130 to 190 degrees C. The oil gets heated in
a heater, naturally!, and conducted to the machine by pipes which
can be handled by hand. Its no big deal to insulate at those rather
mild temperatures. The expense would be enormous, and like
the other post, would the energy saved be more than the energy
cost to build it? I think it would given the large volume of traffic
such a system would allow. Say its one thousand miles long,
traffic could be, would be, co-ordinated to have hundreds or thousands
of units cycling through at any one time.
If a truck takes 400 HP to run, A truck, then 1000 trucks would take
400,000 Hp to run, if you do that every day of the year, you are
talking 100 Gigawatthours or so of energy to so in ten years that would
be one terawatthours. But a tunnel like that would probably have
100,000 trucks so that would represent 100 terawatthours of energy
using regular trucking for ten years. Thats a lot of D cells!

As the transportations units can't meet in the middle you have to have two tunnels.

But nevertheless, we're talking of temperatures here, very strong heat, more than a thousand centigrade...?

We are not drilling to rock all the time. Drilling throug molten lava, a molten iron core, preassures far beyond the deepest see, and this is only a modest description of the hostile conditions we have to drill through.

If the planet was a solid one with no excessive interior heat, that could be done but now we talk about our planet, the Earth...

well this is interesting keep it on the front page

Originally posted by sonhouse
Well it doesn't exactly have to be a permanent magnet but yes you
can, there are lifting magnets now that can be switched in and out
very easily even though they can lift 400 pounds each. Its how its
constructed inside, actuators lift the actual magnet, once you do that
its no big deal to just turn it around. The way it works is by a cam
that separate ...[text shortened]... ly,
they can be enormously powerful and require no energy for the
current, only for cooling.

And would these magnets not consume energy, thus making the system not completely free of loss?

Originally posted by FabianFnas
As the transportations units can't meet in the middle you have to have two tunnels.

But nevertheless, we're talking of temperatures here, very strong heat, more than a thousand centigrade...?

We are not drilling to rock all the time. Drilling throug molten lava, a molten iron core, preassures far beyond the deepest see, and this is only a modest des ...[text shortened]... no excessive interior heat, that could be done but now we talk about our planet, the Earth...

We are talking about something that is more difficult than space travel and probably as difficult as interstellar travel. It would certainlly not be free transportation nothing practical ever is 100% efficient. Buidling a tunnel that could withstand and maintain the pressures of a 100% vaccum in such harse conditions would be economicaly unfeasable. every time one of the units enters the thing air would be introduced that would require energy to remove or are we going to use our telleporter to put the units in and out of the tube? Such a system would require large amounts of maintenance. Why do you think we have gone backwards and are now using trucks to transport what was once done by rail? Rail is far supperior energy wise and yet our raillines are be abbandoned and tore up.

This is complete science fiction!

GV

Didn't Jasper Fforde describe this in his novel _Lost in a Good Book_?

Originally posted by prosoccer
And would these magnets not consume energy, thus making the system not completely free of loss?

They could be either permenant magnets or superconducting,
which require no energy but the cooling.

Originally posted by Nighthawk62
We are talking about something that is more difficult than space travel and probably as difficult as interstellar travel. It would certainlly not be free transportation nothing practical ever is 100% efficient. Buidling a tunnel that could withstand and maintain the pressures of a 100% vaccum in such harse conditions would be economicaly unfeasable. ever ...[text shortened]... and yet our raillines are be abbandoned and tore up.

This is complete science fiction!

GV

Which is why I used the word 'grandiose'. Nobody is suggesting
its a real program to drill a hole all the way through the earth,
no one sane anyway! But the drillers are getting close to the Mohovoric
discontinuity, something like 5 miles deep so its not beyond reason
to think a tunnel could be made, like XanthosNZ says, would be a
chord shaped curve reaching a few miles deep and then back up to
the surface. Like you say, nothing is 100% efficient, and my idea
of using magnets is not 100 % either. Eddy currents will suck some
of the kinetic energy and turn it into heat, and as someone pointed
out, it may take more energy to build than you would save in even
ten years of operation which may be true now but maybe more
efficient diggers will be invented in the future.

http://dsc.discovery.com/convergence/engineering/transatlantictunnel/interactive/interactive.html

Originally posted by Coconut
http://dsc.discovery.com/convergence/engineering/transatlantictunnel/interactive/interactive.html

That is a bit differant, an 'ordinary' tunnel, albeit one helluva long one! No free ride here.