how big is universe ?

@metal-brain said

That proves nothing. I refer you to the equivalence principal.

Are you really that stupid?

I just wrote about the equivalence principle in my post that you replied to.

You refer me to my own post?

That is my point, Junior. There can be time dilation without gravity. Because of this, time dilation itself does not cause gravity. Just like time dilation does not cause acceleration. Gravity OR acceleration causes time dilation. Furthermore, since the effect of both is the same, you do not "need both".

Your education was totally wasted on you.

@averagejoe1 said
Thumb up from AJoe.
Pure logic. Libs, even Thousand, don’t know logic from the cause of gravity.

Einstein identified as a Socialist.

Now give us the contrapositive of the following statement:

"If it is raining, then it is either cloudy or I am dreaming."

@Suzianne
I told him that several times but he is hooked on his scientist of the month club and will NEVER get it. Two separate physics give time 'dilation' so there has to be something more fundamental which says clearly TD is NOT the fundamental here.
Deaf ears.

@sonhouse said
@Suzianne
I told him that several times but he is hooked on his scientist of the month club and will NEVER get it. Two separate physics give time 'dilation' so there has to be something more fundamental which says clearly TD is NOT the fundamental here.
Deaf ears.

Why would gravity cause time dilation?

The post that was quoted here has been removed

You just made my case for time dilation causing gravity, they are intricately and forever linked, you can't have change in time without change in space curves.

@Metal-Brain
No shyte sherlock. They are linked. That does NOT mean time dilation, as you call it CAUSES gravity. THEY ARE LINKED but only MASS or Velocity of mass can change the flow of time. It is MASS as the fundamental here not time 'dilation'.
Without mass there is no change in spacetime curve and no time 'dilation'. ONLY with mass does spacetime respond with a new curve and time flow change.

@sonhouse said
@Metal-Brain
No shyte sherlock. They are linked. That does NOT mean time dilation, as you call it CAUSES gravity. THEY ARE LINKED but only MASS or Velocity of mass can change the flow of time. It is MASS as the fundamental here not time 'dilation'.
Without mass there is no change in spacetime curve and no time 'dilation'. ONLY with mass does spacetime respond with a new curve and time flow change.

How can you have time dilation from mass without bending space?
You are trying to sever the link you have already acknowledged.

Do you see the flaw in your logic?

@Metal-Brain
I DO see the glaring flaw in your understanding.

You don't get the idea of SPACETIME. Time and space are intimately linked.

You bend space, time bends as a result and MASS bends space. And whatever the forces were involved in the big bang. Assuming BB theory is correct and a lot of evidence suggests that is the right way to view our universe.

Thinking about that, the flow of time when it was near the BB, afterwards, that is, time flows faster the deeper into a gravity well you go, that is to say, the most bendy space= fastest time flow so inside must have been interesting when the universe was say the size of a basketball.
Maybe planets formed and disappeared in OUR timeframe of one microsecond and life with it.

@sonhouse said
@Metal-Brain
I DO see the glaring flaw in your understanding.

You don't get the idea of SPACETIME. Time and space are intimately linked.

You bend space, time bends as a result and MASS bends space. And whatever the forces were involved in the big bang. Assuming BB theory is correct and a lot of evidence suggests that is the right way to view our universe.

Thinking ...[text shortened]... ketball.
Maybe planets formed and disappeared in OUR timeframe of one microsecond and life with it.

"You bend space, time bends"

Mass causes time dilation. Time dilation causes space to bend because time and space are inexorably linked. If time dilation does not cause gravity why is the equivalence principal relevant when discussing GR? Why does PBS' Nova keep bringing it up in almost every program about Einstein despite an obvious lack of true equivalence?

@metal-brain said
"You bend space, time bends"

Mass causes time dilation. Time dilation causes space to bend because time and space are inexorably linked. If time dilation does not cause gravity why is the equivalence principal relevant when discussing GR? Why does PBS' Nova keep bringing it up in almost every program about Einstein despite an obvious lack of true equivalence?

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 dilation.

Put twins in the heart of the Bootes Void, and let one race off at 0.99c for 50 lightyears and then return. The twins will be drastically different ages, and neither mass nor gravity would have had anything to do with it.

@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.

If the twin left behind hasn't died of old age.

@Suzianne
For the life of me I can't figure out why MB is so stubborn and refusing to learn.

@sonhouse said
@Suzianne
For the life of me I can't figure out why MB is so stubborn and refusing to learn.

I can. I've encountered the syndrome before, but rarely in so many fields at the same time. It's the same reason circle squarers, perpetual motioners and pi rationalisers never give up.

@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, still quite a long time to have to eat and such.
So 28 or 30 years passes by on ship time to make a round trip but still 200 years pass by on Earth, you arrive in a way different time than when you left and there would be nobody alive you knew at home. And you would STILL be 30 years older.
To make that say one year, you have to go something like 0.99999 c

So our first interstellar journey would have to be Alpha Centauri and at least that is three stars for one trip. At 0.5 c the total trip time would be not much different for the traveller and earth bound time flows. Maybe a year faster for the traveler than the time flow on Earth.
At least you would come back to a civilization not THAT much different, about 8 years compared to the example of traveling 100 light years at .99 c of about 200 years going by on Earth and 30 years for the travellers.