Time Dialation and Biological systems

[Dale]

2) Surely nowhere on Earth would a traveller return from a journey having aged less than the twin he left behind? Does this not violate the example of a principle of biology that I gave?

Please cite a reputable source that specifically identifies that as a principle of biology. I for one have never come upon such a statement listed as a principle in any of my biology texts, so I think it is not an accepted principle.

 

[ghwellsjr]

Do you agree that clocks dilate but your problem is just with biological clocks? In other words, would Alice notice that her clocks were running slower than her own perception of time?

 

[Ryan_m_b]

1) I am quite happy with the term denoting "without research" or indeed "obvious"

It is not a synonym of obvious, it means that the conclusion can be derived without physical evidence from experimentation. I challenge you to derive any information about biology without physical evidence from experimentation (of which your own sensory input would include).

2) Surely nowhere on Earth would a traveller return from a journey having aged less than the twin he left behind? Does this not violate the example of a principle of biology that I gave?

Actually they would have but by such a tiny amount it's inconsequential. The difference between an airport clock and an aeroplane clock after a journey is virtually undetectable. Essentially a it's because at no point would the traveller have accelerated to relativistic speeds relative to an observer.

 

[Mark M]

2) Surely nowhere on Earth would a traveller return from a journey having aged less than the twin he left behind? Does this not violate the example of a principle of biology that I gave?

Ryan, DaleSpam, and ghwellsjr have been re-iterating this to you over and over - in YOUR reference frame YOU feel time passing normally. ANOTHER observer in a different reference frame sees your time moving slowly, your body slowing down, and your clock ticking slower. But YOU always feel normally.

This is a fact. There aren't any 'principles of biology' that contradict this.

 

[BruceW]

2) Surely nowhere on Earth would a traveller return from a journey having aged less than the twin he left behind? Does this not violate the example of a principle of biology that I gave?

Even on planet earth, time dilation will have an effect. (As Ryan_m_b also said). If I ride about on a fast train all my life, then when I eventually stop and meet with my stay-at-home twin, then I will have lived for about a second less time than he has lived.

To put it another way, the space time interval of my journey will be less than that of my twin, because I have been accelerating around on the train. And the space time interval is the same as the time which has passed for that person, so I will end up a little bit younger than my twin.

 

[PAllen]

So let's suppose the world worked according to what indirachap suggests. Then, if someone else travels very fast near me, I notice that my clocks (both light and mechanical), and radioactive decay, slow down compared to my biological time perception. If no one else moves fast near me, this does not happen. !??

 

[DennisN]

Poppin' in, first time I post in the Relativity forum, I think, hi!

Biology is governed by physics, not the other way around (this does of course not mean biology as a science is less important).

indirachap, I have read the entire thread and I have a suggestion. Many years ago I struggled myself with accepting relativity, since I found it counterintuitive (speed of light as a basis, length contraction, time dilation etc). My road to accepting the theory was not straightforward, but these were some of my important steps;

"How I Learned to Stop Worrying and Love Relativity":

1. Learning the basics of the theory.
2. Questioning it on various grounds (counterintuitive, hard to grasp etc)
3. Checking how tests and experiments matched up with the theory (it beats Newton et.al.).
4. Learning more thorougly about the theory (and adding a little General Relativity too).
5. Trying to fit it into my worldview.
6. Accepting it.

I don't know at which stage you are, but here is one suggestion from me:

Forget about the concept of an absolute, universal time. There is no universal clock which governs everything. Thus, a clock ticking on Earth is universally "meaningless", it's only important to someone on Earth (and the same goes for "space", there's no absolute, universal space; there is spacetime).

If you can make yourself accept this, you might find that time dilation is not particularly counterintuitive. For person A, clock C_A shows time T_A, perfectly normal to person A. For person B, clock C_B shows time T_B, perfectly normal to person B. But this does not necessarily mean time T_A = T_B, as there is no time T_U = universal, absolute time. If there was a universal time, then we could adjust our clocks to T_A = T_B = T_U. Remove the absolute, universal time T_U, forget it, and set T_A ≠ T_B (yet, of course, T_A = T_B if A and B are at rest with respect to each other).

 

[ZapperZ]

The original question has been answered several times. This thread is done.

Zz.