Time travel

[Brutal]

Please imagine and airport on the equator, with 2 identical airplanes sitting tail to tail. The both take off at the same time in opposite directions flying around the earth to land back at the same airport. 1 will be flying with the earths rotation and 1 against. Flying at a speed of 500mph is it true that one will get back to the airport before the other ie the one going against the earths rotation, and will one plane be traveling very slightly forward in time and one backwards in time relative to the people they are flying over on the journey.

[Harley]

Assuming there are no adverse headwinds they will both arrive at the same time.The Earth's rotation has no effect on relative position as it all moves together as a single mass.A Harrier Jump jet in hover has no forward speed even though the Earth is rotating.Think about it !

[BenDToy]

I have a further puzzle which I can't get my head around. If you travel one way round, you move your clock forward by one hour each time you cross a time zone, and the other way you move your clock backwards. It seems to me that, when they are half way round, one has crossed 12 time zones (hours) forward, and the other has crossed 12 time zones backwards, relative to the point where they started. They are in the same place but 24 hours apart in time, which must be wrong, but where is the flaw in my logic? Also if they continue the whole way round, why are they then not 2 days apart?

[Moog]

BenD Toy you are right the will be exactly 24 hours between them which is why we have the international date line where you eith lose of gain a day depending on which whay you travel so in the situation you describe one or other of the planes will of crossed the date line thereby losing or gaining a day depending on which way travelling so when they meet it is still the same time

[Haitch]

Timezones are just a convenience for us humans so we all get up in the morning and not the afternoon (students excluded). They have no bearing on real linear time. A second is still a second. Just because someone may be in a timezone ahead of us it doesn't mean they are in the future, just that the sun rises there first.

[Brutal]

Harley, I have to disagree with you, The earth is turning at about 1100Mph and if you are travelling against the rotation of the earth by definition the airport will turning towards you as you are going towards it, so you must reach your destination quicker than a plane travelling with the earths rotation as that plane is always playing catchup.

[sft42]

Brutal you have forgotten that the planes speeds are measured relative to the rotation of the earth. if you were right your plane going against the rotation would have to fly at 1100mph just to stand still!!

[TexMutt]

Brutal would be correct IF the question stated that the planes were traveling tat the same rate instead of stating a mph which is measured relatively as sft42 stated.... (I thinks)

[Brutal]

sft42 I think you may be incorrect, the speed of a plane is determind by how fast it is being prushed forward, an air pressure reading is taken outside of the aircraft and compared to the static pressure inside the aircraft. The result does not have any inclusion of the earths rotation. Also you would not have to be moving at 1100mph to stand still beacuse you are bound by the earth and its atmosphere - You are already travelling at 1100mph - We all are all of the time.

[Hamish]

Hi Folks, sorry i missed out earlier on this one. If you measure the speed by measuring air pressure you are measuring the planes speed relative to the airs speed (pressure) which is relative to the grounds speed (ie air is not stationary but moving relative to the earth (depending on how windy it is) as far as I know there is no stream of air moving at 1100mph. therefore the speeds are still relative to the earth. Speed has to be a relative thing as it must be measured from something, there is not absolute speed, unless you scale speed to the speed of light which is a constant in a vacuum.

[TexMutt]

OK, I was tired when I typed my last response. Actually, HARLEY is correct. Our atmosphere is rotating along with the earth and it would have no effect on the planes. Otherwise every time a coin was flipped before a football game the winner would pick to go against the rotation instead of with the wind!