question about time

[zoidburg111]

am i the only one who thinks time is an absolout constant and cannot be chaged?? (i.e. traveling the speed of light).after all isnt time mearly a perception of the mind.doesnt time drag along say when your at the dentist but seem to fly by when your doing something enjoyable?.i also believe u can travel at the speed of light,its just a matter of shielding,fuel,and building up to it (not like star trek etc...) and time will not change.just a theory of mine and please refrain from calling me an idiot because i dont agree with popular theories

[ecidyalpsoeddog]

You touch on an interesting point and that is that in order to travel at something approaching LS, you would first have to accelerate to that speed, you likely would then travel at the LS for only a short time (when compared to the whole length of your journey) before spending a lengthy time slowing down again.

[zoidburg111]

i thought about that a little while after posting the 1st time.youd pretty much could only ever go 1/2 of your trip at LS,the last 1/2 would be slowing down at a low enough rate so as not to rip yourself apart.also wanted to say i view "time" as a non-issue,meaning it can never be altered in any way."time marches on" so to speak.another question...does light succumb to the doppler efeect like sound? like the closer u get to LS will object in front of u get brighter and object behind grow darker?

[Samuel Nathan Richards]

The doppler effect for the electromagnetic spectrum is called "Red-Shift" or "Blue-Shift" depending on which way you are going. The object going away is red-shifted and the objects coming towards you are blue-shifted. Temperature has an effect on this, by the hotter the gas the more energy it has and therefore is blue-shifted, opposite for red-shift.
Question: Doesn't your mass increase as you approched light speed?

[Elanor]

I'm not entirely clear what the question is, but time isn't a constant; it varies according to your reference frame and will slow down the faster you travel. Of course you won't notice this as everything else - your watch, heart rate, etc. - will also slow down.

With regard to travel at light speed, it requires an infinite amount of energy to accelerate to light speed, which is why you can only do it if you have zero mass (like a photon, which is why light travels at the speed of, well, light). As you get closer and closer to a speed of c time gets slower and slower. Should you actually reach c, time would stop completely, which is why photons do not age (so to speak).

[Samuel Nathan Richards]

When light enters a medium other than a vacuum it's speed is decrease, albeit a lot of the time quite insignificantly. If, under your reasoning, photons don't age due the time standing still at "c" then when light enters this other medium, it is then affected by time and can age.

Just a thought