When will we reach the Moon, Mars, Jupiter, another star and another galaxy...

[Energize]

Trust me this is wrong. I did a course on relativity at uni (and got 86%, yeah I'm the man). The journey will appear shorter for observers on earth, but for the people in the spaceship it will take exactly the same amount of time.

As the experiment I linked to shows, less time passes for people travelling at high velocity, hence why the clock on the plane shows it has experienced less time than those on earth.

What you are suggesting is basically amounts to travelling faster than the speed of light (speed = distance/time, so 25000 light years / a few days would be greater than c, i.e. impossible).

Your forgetting lorentz contraction, from the people on the shuttles reference, the distance they have to travel is shorter, if they were travelling at 99% the speed of light the distance between the shuttle and the nearest galaxy would only be 3,571 light years away from their perspective, not 25,000.

There's a million videos on youtube of professors explaining this.

http://www.youtube.com/watch?v=UOvOFVpJOKs&feature=related

http://www.youtube.com/watch?v=VSRIyDfo_mY&feature=related

http://www.youtube.com/watch?v=gdRmCqylsME

 

[Mojo]

They are all achievable (except possilby the next galaxy, no bleedin' point). However, Only the first two are likely to be realised to a great degree simply because the ability to commercially exploit both the Moon and Mars is possible with investment. The Moon is ideal for mining and sensitive materials construction due to it's lower mavity, allowing a lesser expenditure of resources to produce craft/ transport materials to a zero gee environment. However, getting materials back to earth cheaply and without harming the local ecology is a tricky one. Heat shields capable of repeated re-entry aren't cheap you know =P

 

[Freefaller]

Has anything ever been measured at travelling faster than the speed of light? Even if we could go 10x faster, something 10 light years away would still be 1 year's worth of travel no? Or is it not that simple?

What about Quantum physics, doesn't that state that a particle can be in more than 1 "state" at once, ergo, more than 1 place at a time? Does this add any weight to the argument of bending space/time significantly enough to achieve a point to point bit of travel?

I think personally, whether or not this is accurate I care not, that going faster than the speed of light is an improbability, and the significance of doing it is unfathomable. However I think a "wormhole" idea is far far more "believable" in a strange way.

 

[Methanoid]

Go on, put your scifi heads on and predict how many years till:-
- A human lands on the Moon again
- A human lands on Mars
- A human reaches Jupiter (Arthur C Clarke said we'd already be there )
- A probe or human reaches another star
- A probe or human reaches another galaxy

Moon - 10 years - and he will be Chinese!!!
Mars - 20 years - it could have been done many years ago. Read The Case for Mars by Robert Zubrin (President of the Mars Society) for just how "easy" it is
Jupiter - I assume you mean orbit and not landing? No real reason to orbit Jupiter but I reckon a Gallilean moon is a possible landing site but again no real reason.
Probes - not in the next 500 years and who knows if Man will last that long!

 

[EvilOne]

On the contrary, I believe most people under estimate it. We've envisioned many new propulsion methods over the past half century which would have been inconceivable before the Cold War.

Just look at the breakthroughs of shooting laser beams into titaniam atoms to create fusion (same power sorce as the sun). Once they perfect and miniturise this tech, power supply for long trips should be pritty easy to manage.

Your forgetting lorentz contraction, from the people on the shuttles reference, the distance they have to travel is shorter, if they were travelling at 99% the speed of light the distance between the shuttle and the nearest galaxy would only be 3,571 light years away from their perspective, not 25,000.

But it will still be 25,000 years for everyone else not on the shuttle.

 

[NeilF]

- A human lands on the Moon again
Only one on the list viable really.

- A human lands on Mars
Never.

- A human reaches Jupiter (Arthur C Clarke said we'd already be there )
Never.

- A probe or human reaches another star
The heat would kill you, Never.

- A probe or human reaches another galaxy
Too far, Never.

Note the change in words... "land" & "reach"... Reach could suggest get near to, for example get into a local orbit...

 

[NeilF]

They are all achievable (except possilby the next galaxy, no bleedin' point). However, Only the first two are likely to be realised to a great degree simply because the ability to commercially exploit both the Moon and Mars is possible with investment. The Moon is ideal for mining and sensitive materials construction due to it's lower mavity, allowing a lesser expenditure of resources to produce craft/ transport materials to a zero gee environment. However, getting materials back to earth cheaply and without harming the local ecology is a tricky one. Heat shields capable of repeated re-entry aren't cheap you know =P

We need a space elevator!

 

[Inquisitor]

Trust me this is wrong. I did a course on relativity at uni (and got 86%, yeah I'm the man). The journey will appear shorter for observers on earth, but for the people in the spaceship it will take exactly the same amount of time.

What he's saying is that for a given distance in the lab frame, the closer the moving frame gets to the speed of light, the less food the travellers will need for the journey (a truism I suppose), which is due to time dilation.

What you are suggesting is basically amounts to travelling faster than the speed of light (speed = distance/time, so 25000 light years / a few days would be greater than c, i.e. impossible).

What? You're comparing time and distance as measured in different frames. It may only take several days in the moving frame, but then due to length contraction the distance involved will be far, far less than 25,000 light years; conversely, if measured in the lab frame, then the distance will still be 25,000 light years, but the time taken will be correspondingly much greater. There is no violation of relativity.

Maybe I'm just misunderstanding your disagreement or something.

But it will still be 25,000 years for everyone else not on the shuttle.

Sure, but due to time dilation their clocks (and hence metabolism) will be slow, so they'll need less food.

 

[Dugganator]

We need a space elevator!

I could see this question being a funny one...... which floor would be like

But I guess there would only be one floor anyway.

 

[Dugganator]

I could see this question being a funny one...... which floor would be like 19056552

But I guess there would only be one floor anyway.

Error meant to edit not quote my self damn my banana hands

 

[NeilF]

I could see this question being a funny one...... which floor would be like

But I guess there would only be one floor anyway.

No two... Ground and first floor...

 

[lord filbuster]

Trust me this is wrong. I did a course on relativity at uni (and got 86%, yeah I'm the man). The journey will appear shorter for observers on earth, but for the people in the spaceship it will take exactly the same amount of time. What you are suggesting is basically amounts to travelling faster than the speed of light (speed = distance/time, so 25000 light years / a few days would be greater than c, i.e. impossible).

This is correct. The shortest amount of time will be measured by the clock which is not moving relative to ship, I.E the one onboard. Time will not slow, and length will not contract for the people on the ship. For instance, a ship travelling at 0.999c, the occupants will still measure it taking 4 years to get to say, alpha centuri, but for an observer on earth it would appear to take 20 years for them to get there. It will not allow them to get to other places in less time.
I'm not sure what happens with time when you are actually at light speed, since the maths breaks down.

 

[KNiVES]

To the moon landing naysayers; you know with current tech it's practically a joke to pull off now. If we can keep the ISS in orbit and operational with constant spacewalks and maintenance, landing on the moon isn't far behind in terms of scale either.

Landing on the moon is perfectly achievable, just like it was all those years ago. Just look at what we currently have, then try to say to yourself 'nah ain't happening'.

 

[Fusion]

Has anything ever been measured at travelling faster than the speed of light? No, nothing with mass can reach the speed of light, it requires an infinite amount of energy. Massless particles always travel at the speed of light. Particles with an "Imaginary" (mathematically speaking) mass have been hypothesised, and they would actually travel back in time, but this is relevant to our discussion as it's just a theory without basis

What about Quantum physics, doesn't that state that a particle can be in more than 1 "state" at once, ergo, more than 1 place at a time? Does this add any weight to the argument of bending space/time significantly enough to achieve a point to point bit of travel?

The Pauli Exclusion Principle says that no two Fermions (i.e. Electrons, Protons, Neutrons) may have the same quantum numbers (parameters such as Spin) in the same region of space, so for example no two electrons in an atom can have the same set of quantum numbers.

This places no restriction on creation of wormholes, it's just about matter occupying the same space.

 

[NeilF]

This is correct. The shortest amount of time will be measured by the clock which is not moving relative to ship, I.E the one onboard. Time will not slow, and length will not contract for the people on the ship. For instance, a ship travelling at 0.999c, the occupants will still measure it taking 4 years to get to say, alpha centuri, but for an observer on earth it would appear to take 20 years for them to get there. It will not allow them to get to other places in less time.
I'm not sure what happens with time when you are actually at light speed, since the maths breaks down.

That makes no sense... If alpha century blew up, the light would inform us of the event 4yrs later, not 20yrs later? ie: If your craft left alpha century for earth, basically travelly as near to the speed of light as possible, why would it not arrive after four years as far as everyone else is concerned on earth?

 

[Fusion]

This is correct. The shortest amount of time will be measured by the clock which is not moving relative to ship, I.E the one onboard. Time will not slow, and length will not contract for the people on the ship. For instance, a ship travelling at 0.999c, the occupants will still measure it taking 4 years to get to say, alpha centuri, but for an observer on earth it would appear to take 20 years for them to get there. It will not allow them to get to other places in less time.
I'm not sure what happens with time when you are actually at light speed, since the maths breaks down.

Both you and Souness are wrong. Why would observers on Earth see something travelling at 0.999c taking twenty years to reach Alpha Centuri? That's wrong for starters, it would only take marginally more than 4.3 years, a trivial calculation which doesn't even need to take relativity into account, it's just a simple speed = distance/time relation.

The people on board do notice their clocks passing by slower, this is a real and experimentally verified phenomenon. In 1972 two american physicists, J.C. Hafele and Richard E. Keating conducted an experiment using four extremely accurate cesium atomic clocks. Two clocks were flown on commercial jet aircraft around the world, one eastward and one westward; the other two reference clocks stayed fixed on the earth in the lab.

Negating the effect of the Earth's rotation, the moving clocks ticked slower and hence time measured on board the aircraft was shorter.

 

[lord filbuster]

Both you and Souness are wrong. Why would observers on Earth see something travelling at 0.999c taking twenty years to reach Alpha Centuri? That's wrong for starters, it would only take marginally more than 4.3 years, a trivial calculation which doesn't even need to take relativity into account, it's just a simple speed = distance/time relation.

The people on board do notice their clocks passing by slower, this is a real and experimentally verified phenomenon. In 1972 two american physicists, J.C. Hafele and Richard E. Keating conducted an experiment using four extremely accurate cesium atomic clocks. Two clocks were flown on commercial jet aircraft around the world, one eastward and one westward; the other two reference clocks stayed fixed on the earth in the lab.

Negating the effect of the Earth's rotation, the moving clocks ticked slower and hence time measured on board the aircraft was shorter.

Yes, you are right, i neglected length contraction. A correct version of what i wrote would be, in 20 years, 4.3 years pass for the ship. So in 4.3 years on earth, the ship would reach alpha centuri, and yet the passengers would only age a month or so. However, both the earth and the ships observers would not notice time pass any differently.

 

[NeilF]

Not really, your accelaration is given by the centripetal accelaration formula:

a = w^2*r

a = accelaration
w = angular velocity in rad/s
r = radius

So for a 20m diameter ship (quite modest), you'd need to spin at 1 rad/s or 1 revolution every 6 seconds for 1G.

That reminds me, anyone remember on armageddon where they added a spin to Mir to give it artificial mavity? Best comedy of the year

So my noddy physics suggested if a 20m ship rotated once every 6 seconds to produce 1G, then if it rotated at once every 12 seconds that would produce 0.5G. But Energize said would have to rotate at once every 8.57 seconds to instead produce 0.5G.

Someone able to explain that?

EDIT: A google search says the formula is actually a = w^2 / r !!! With 1 radian = 57.2957 degrees

So to produce 1G is square root of 10 (m/s) / 10 (meters) = 1 radians = about 6 seconds to do one rotation.

So to produce 0.5G is square root of 5 (m/s) / 10 (meters) = 0.7071 = just under 9 seconds...

So there you go... Managed to work it out myself... Don't understand how speeding up the slower rotation by 33% gives you 100% more angular force though

 

[Inquisitor]

Observers in the lab frame (Earth) observe the shuttle to be travelling at 0.999c toward Alpha Centauri, so it'll take just over 4.3 years for the shuttle to reach Alpha Centauri. There's no relativity involved here.

Relativity comes into play when we switch to the frame of the shuttle. In this frame, the distance to Alpha Centauri has contracted, and Alpha Centauri has a velocity of -0.999c (toward the shuttle). From this frame, the time taken to get there is less because of the contracted distance.

This is consistent with the observations from the lab frame, since, while the distance is still 4.3 light years, the clocks on board the shuttle are slow.

The people on board do notice their clocks passing by slower, this is a real and experimentally verified phenomenon. In 1972 two american physicists, J.C. Hafele and Richard E. Keating conducted an experiment using four extremely accurate cesium atomic clocks. Two clocks were flown on commercial jet aircraft around the world, one eastward and one westward; the other two reference clocks stayed fixed on the earth in the lab.

This isn't correct! The whole idea behind relativity is that velocity is a relative quantity, so it's impossible to determine one's velocity without an external reference point. Consequently they won't notice their own clocks running slowly; if they did, then they'd be able to determine their own velocity without such a reference point, which is in violation of relativity.

 

[Fusion]

It doesn't work like that. An observer on the ship will not notice time running slower, so they will measure it taking 4.3 years to reach alpha centuri. This is called 'proper time.' However, an observer on earth will notice the clocks on the ship running slower, hence why it would appear to take them 20 years to get there.
What will not happen is that the observers on earth will time the ship taking 4.3 years, and the people on the ship timing it as taking a month. This would mean that the people in the ship travelled faster than light, which is impossible. (without all that space bending jazz)

You're wrong again. I've no idea where you're pulling this twenty years figure from. We measure the time to be 4.3 years in Earth's reference frame, taken to be stationary relative to the ship's movement. Moving clocks run slower, so they time the journey to be less than this. That's all there is to it.

Look at the example of Muon decay. A muon moving at 0.99c will have it's half-life measured by a stationary observer to be 15.6 microseconds. In our reference frame, the Muon will have travelled 4630m in this time. In the Muon's reference frame, this time is 2.20 microseconds.

So wait; speed = distance/time, speed = (4630m/2.2 x 10^(-6)s) = 2.1 x 10^9 m/s? That's seven times faster than light. But in the Muon's frame of reference, it thinks it has only travelled 653m, meaning that it's speed is still 0.99c and the laws of relativity remain intact.

At 0.999c, gamma is 22.366 so it would indeed seem to those on the ship that they had only been travelling for a few months.