# The Naked Scientists Forum

### Author Topic: twin paradox  (Read 17140 times)

#### thebrain13

• Sr. Member
• Posts: 442
##### Re: twin paradox
« Reply #50 on: 26/07/2006 19:39:30 »
you can use multiple forces, in whatever magnitudes. Your argument is that it is impossible to accelerate an object uniformly without using gravity, that is not the case.

#### ukmicky

• Moderator
• Neilep Level Member
• Posts: 3011
##### Re: twin paradox
« Reply #51 on: 26/07/2006 22:30:20 »
quote:
Originally posted by thebrain13

you can use multiple forces, in whatever magnitudes. Your argument is that it is impossible to accelerate an object uniformly without using gravity, that is not the case.

What other forces  can act on and  accelerate  every single atom in a body equally or how would you use multiple forces to act on every atom equally

Michael
« Last Edit: 27/07/2006 00:41:39 by ukmicky »

#### thebrain13

• Sr. Member
• Posts: 442
##### Re: twin paradox
« Reply #52 on: 27/07/2006 01:04:31 »
yes, use multiple forces to accelerate the atoms equally.

#### another_someone

• Guest
##### Re: twin paradox
« Reply #53 on: 27/07/2006 01:23:44 »
quote:
Originally posted by thebrain13

yes, use multiple forces to accelerate the atoms equally.

But you have still evaded answering the question – what is the force, or what are the multiple forces, you would use.  To say there are more than one of them does not tell us what they are.

George

#### thebrain13

• Sr. Member
• Posts: 442
##### Re: twin paradox
« Reply #54 on: 27/07/2006 01:28:18 »
electric charge

#### another_someone

• Guest
##### Re: twin paradox
« Reply #55 on: 27/07/2006 01:57:38 »
But electric charge has no effect upon electrically neutral entities.

Electric charge has no effect upon a neutron at all.  Electric charge has an opposite effect upon the electrons and the protons within an atom, and so the overall effect upon an electrically neutral atom will be nothing at all.  Furthermore, electric charge, although it can have a polarising effect upon photons, it will not cause and attractive or repulsive force upon a photon, since a photon is also electrically neutral (and the red shift in a laser or radar beam could be used to construct an accelerometer).

George

#### thebrain13

• Sr. Member
• Posts: 442
##### Re: twin paradox
« Reply #56 on: 27/07/2006 02:50:13 »
Then use Electric charge, and Nuclear strong force. Cant you just drop this argument? The only way you can win is if you prove that accelerating an object uniformly is impossible. Which makes einsteins equivalence principle meaningless. Im implying if you did, what would happen, I dont need to make the experiment.

#### another_someone

• Guest
##### Re: twin paradox
« Reply #57 on: 27/07/2006 03:42:35 »
quote:
Originally posted by thebrain13
Then use Electric charge, and Nuclear strong force. Cant you just drop this argument? The only way you can win is if you prove that accelerating an object uniformly is impossible. Which makes einsteins equivalence principle meaningless. Im implying if you did, what would happen, I dont need to make the experiment.

Photons, neutrinos, and much else are effected by neither electric charge nor the strong nuclear force.

Protons are neutrons are effected by the strong nuclear force, but the range of the strong nuclear force is so short that it cannot be felt outside the nucleus of the nucleus of the atom, so there is no way of using it to effect a group of atoms.

Einstein only postulated two equivalences – that if inertial reference frames, which is not the case we are discussing; and that between uniform acceleration (caused by the curvature of space) and gravity.  He made no suggestion that anything but a curvature of space itself could cause the kind of equivalence that you suggest.

George

#### thebrain13

• Sr. Member
• Posts: 442
##### Re: twin paradox
« Reply #58 on: 27/07/2006 03:53:01 »
yes he did. Why do you think he called it the equivalence principle?

Because gravity is equivalent to uniform acceleration.

What Einstein never says, is only gravity can create uniform acceleration. Unless you can find where he says that, in which case, I stand corrected.

#### heikki

• Full Member
• Posts: 56
##### Re: twin paradox
« Reply #59 on: 27/07/2006 11:20:06 »
quote:
Originally posted by thebrain13

lets say there are two spaceships containing one pilot each, they are identical twins of course. We'll call them pilot a and pilot b. pilot b fires his engines and travels at 99 percent the speed of light away from pilot a for one year. Then turns around and comes back. Einstain says that from pilot a's perspective pilot b would have aged less than him. However Since velocity is relative to each observer, pilot b sees pilot a speeding away from him and then returning. So pilot b should see a younger pilot a. So my question is when the two meet each other after the trip which one is younger?

Hi, Thebrain13.

I both pilot travells 1 earthyear then they both are same age. If hundred year then they are 100year. Still same age.

If travelling speed is different a and b, x m/s, still s is actual same both. Only m is different and changed.

Can use timeunit, earth s or "constant" s, still 1s is 1s. What else it can be? 1s cannot be 1/2s or 2s.

Therefore my answer to your question is that both space-traveller going do aged at same time. Of cource and because our body is like other mammals fir to earth nature through many and many generation it control that ageing-process and different speed on space can happend some genetical-cell basic changes and then other traveller can be little seems yonger, but still, earth-year-age is same.

#### tarbag

• First timers
• Posts: 1
##### Re: twin paradox
« Reply #60 on: 27/07/2006 22:49:11 »
quote:
. Einstain says that from pilot a's perspective pilot b would have aged less than him.

According to the experiment of Michelson Morely we deduce that the theory of special relativity  is valid for the light signals or the  electromagnetic waves.Why thus apply it for material bodies. It is not  a confusion here.
Well cordially

#### The Naked Scientists Forum

##### Re: twin paradox
« Reply #60 on: 27/07/2006 22:49:11 »