how big is universe ?

@sonhouse said
@Suzianne
It sucks that you have to get very close to c to have much effect on perceived travel time. Like at 0.5 c, you only save about 15% of perceived travel time which is SOMETHING but not a project for the record books. It only gets significant at 0.99c or so. At that velocity, a trip of 100 light years would take you inside the ship a perceived time of about 14 years ...[text shortened]... eling 100 light years at .99 c of about 200 years going by on Earth and 30 years for the travellers.

@Soothfast
Well then they would never live to see the large magellenic clouds:"😉
Well maybe if they could go 0.9999999999999999c but they would get back to Earth about 300,000 years later🙂

@soothfast said
I think I already said this, but general relativity and special relativity are different theories. If there is some mathematical "equivalence principle" in which one could characterize all general relativistic time dilation as being caused by gravity and vice-versa (and I believe there is such an equivalence), it would not apply to special relativistic time d ...[text shortened]... l be drastically different ages, and neither mass nor gravity would have had anything to do with it.

@Metal-Brain
You are so full of SHYTE your NOSE must smell bad.
Matter JUST SITTING THERE makes time flow to go slower, there does not have to be a second mass to make that happen.

MASS is what causes BOTH gravity and time 'dilation'. But Time dilation also happens with VELOCITY having NOTHING to do with mass, ANY mass going close to c will have the flow of time slow down JUST LIKE being stuff of greater mass sitting still.

Don't know what it takes to make you understand that but you are stuck on Greene so whatever he says is your new religion. You WORSHIP Greene.

He brought up SR because there is this SLIGHT possibility you need to study it as well.

@sonhouse said
@Metal-Brain
You are so full of SHYTE your NOSE must smell bad.
Matter JUST SITTING THERE makes time flow to go slower, there does not have to be a second mass to make that happen.

MASS is what causes BOTH gravity and time 'dilation'. But Time dilation also happens with VELOCITY having NOTHING to do with mass, ANY mass going close to c will have the flow of time slow do ...[text shortened]... P Greene.

He brought up SR because there is this SLIGHT possibility you need to study it as well.

@Metal-Brain
It's funny how you say 'time dilation' CAUSES gravity but then say MASS causes 'time dilation'. Clearly you don't understand the difference.

@sonhouse said
@Metal-Brain
It's funny how you say 'time dilation' CAUSES gravity but then say MASS causes 'time dilation'. Clearly you don't understand the difference.

@metal-brain said
The only one who brought up special relativity is you and I don't know why. GR is about gravity, not SR. Matter causes time dilation. Time dilation from mass is gravity.
The time difference is what causes matter to attract. The more the time difference the greater the attraction.

As Brain Greene put it, things do not like to age. Objects move to where time passes sl ...[text shortened]... ce of gravity and please do not say gravity is not a force or I will tell you to jump off your roof.

@soothfast said
I bring up special relativity because you're insisting there is a one-to-one correspondence between time dilation and gravity that does not exist. If time dilation occurs at relativistic speeds, which it does, then "time dilation is gravity" is a false statement.

@Metal-Brain
TD can happen without gravity, with velocity of some mass ONLY.
That throws a monkey wrench into your gravity and TD are the same.

@sonhouse said
@Metal-Brain
TD can happen without gravity, with velocity of some mass ONLY.
That throws a monkey wrench into your gravity and TD are the same.

@Metal-Brain
Tell that to the particles with known lifetimes measured in microseconds but last long enough for bits of them to be counted on the ground because they are going so close to the speed of light but have mass so say 99,99999X c, they last long enough to be counted on Earth.

But since you only had a 5th grade education you would never have encountered THAT one. Which I learned in the 9th grade.

@sonhouse said
@Metal-Brain
Tell that to the particles with known lifetimes measured in microseconds but last long enough for bits of them to be counted on the ground because they are going so close to the speed of light but have mass so say 99,99999X c, they last long enough to be counted on Earth.

But since you only had a 5th grade education you would never have encountered THAT one. Which I learned in the 9th grade.

@metal-brain said
Einstein's General Relativity equation has a "T" for time in it.

@shallow-blue said
That's as sane an argument as noting that it has a 'c' for Constant in it, and concluding that therefore, the universe cannot change.

You really are a poster child for not letting mental toddlers paddle in the Pierian spring.