Ultimate fate of the universe

aku_EnSeM

oic... it is then can be concluded that the total amount of dark energy in this world is increasing by time to counter the decrement of density caused by the expansion of universe, isn't it?

where does this extra dark energy come from, cipan?

cipanbakar

maybe from vacuum energy. space expansion produce vacuum energy which then give 'free energy' for more expansion and go on..

dark energy same as dark matter in term of their mysterious (in fact dark energy is more mysterious than dark matter). we onli know its existence through calculation. it exist becoz calculation said so!

for dark energy there is many different ideas about its nature (there is no definite nature since we dont even know this dark energy even at lowest level). one of the idea is the cosmological constant which said it must consntat all the time.others also speculate that it is not constant but will decreasing and in the future can cause big crunch. others school said it actually increasing and will change to phantom energy and big rip will happen in the end..

i support the constant one becoz it originally came from einstein there was a time when einstein admit cosmological constant was his greatest blunder(when edwin hubble show him universe is not static but expanse). and everybody already forgive him for that until half century later people start looking back to this blunder and admit that it was not a blunder at all(he just put the wrong number but no need to shame since till now nobody know the exact number). his 'blunder' is the only way to explain the accelerating of universe expansion easily..

aku_EnSeM

so, i reckon that this expansion of universe is exactly inevitable... as universe expands, vacuum energy is created, which in turn causes more dark energy to occur, which then leads to more rapid expansion, which causes more vacuum to exist, and produces more dark energy, that would than causes more expansion,....................

then, however, if the critical density of universe is higher than 1 omega.. (is it omega)? then, the expansion would slow down, then the rate of creation of vacuum decreases, and is equivalent to the decrement of creation of dark energy, which would then causes further decrement, until eventually the expansion would become zero, and the matter would cause the universe to contract... is this right?

then, the conclusion is, dark energy is still embedded as a mathematical property of the universe... is it?

so, dark energy causes negative mass, which in turn causes negative gravity that pushes thing... is this still true? if this is true, then can we say that dark energy is just a mathematical expression for the universe? unlike dark matter, which is defined as the matter that we cannot see... if dark energy is just a mathematical expression, then i believe that a lot of experts might argue the existence of dark energy... does this scenario exist?

aku_EnSeM

does dark energy mean negative energy?

cipanbakar

yes exactly!!

dark energy is just mathematical expression. first it came from einstein's field equation. when saw it, scientist Friedman said it show that the universe should be expanding. then Lemaitre support this suggestion and solve it mathematically. he even suggest that universe start from a small dot which now we known as big bang. einstein curse them both as a good mathematician but a failure cosmologist. and he give a value to the constant just to show that universe is static because he was static universe's supporter (big bang's opponent). then hubble proved that he was wrong. then he dump the constant. but 10 years ago, scientist proved that the universe expansion actually accelerated. so now we need the constant again to explain this. and that's how dark energy 'created'. so it just a mathematical term

but from WMAP (the cosmic microwave background map), it also shown there is something missing from our universe map and it account around 70%. they reckon it as dark energy..


neway dark matter also come from mathematical expression. this time it come from newton's gravitational law. base on our understanding, stars speed orbiting around galaxy depend on their distance. the farther from the centre, the slower the star's speed would be such as happen in our solar sistem. if pluto move at the same speed as mercury, it will flown away since sun unable to hold it anymore. but from observation, the star's speed at galaxy's outer region same as stars in the inner region. from our understanding, the star should flown away. but its not. so there must be something that help to hold it. and this 'something' is wat they regard as dark matter. so it just another mathematical expression same as dark energy


and yes, there is argument about its existence. in fact, it is the hottest topic in town..

cipanbakar

Originally posted by aku_EnSeM at 28-7-2007 02:15 AM
does dark energy mean negative energy?

what do u mean?

aku_EnSeM

ermm... consider this if this is valid, yea...

if we have positive energy, then E=mc^2 and this energy region should also exert some attraction gravitational force, is this right?

then, we could also have negative energy, with negative mass, that might exert repulsion gravitational force... ermm... am i going too far?

cipanbakar

erkkk wat is this? are u giving new name to dark energy base on the mathematical equation? or are u trying to relate dark energy with known negative energy?

aku_EnSeM

wow... it is not that radical....

make it lighter than that...

so, do we have a negative energy? not relative ones like in bohr's atom... do we have absolute negative energy? hehehehe....

yea... if we have expanding universe, than something must be in existence to counterthe  gravitational force of matter in this universe... this something perhaps contribute to repulsion gravitational force... it is then negative mass, negative energy...

ermm.. from ur question in previous post, i dont know what the answer is... but it is more to giving mathematical representation of dark energy.... this is based on the principle that dark energy contributes to the expansion of the universe... directly concluding, this dark energy must oppose gravitation... however, if there exist more complicated explanation than this, i'd like to hear it...

cipanbakar

yea... if we have expanding universe, than something must be in existence to counterthe  gravitational force of matter in this universe... this something perhaps contribute to repulsion gravitational force... it is then negative mass, negative energy

yes. it is known as dark energy. why u need another name? the negative negative thing wat is it? to make the subject more fancy?

ermm.. from ur question in previous post, i dont know what the answer is... but it is more to giving mathematical representation of dark energy....  this is based on the principle that dark energy contributes to the expansion of the universe... directly concluding, this dark energy must oppose gravitation... however, if there exist more complicated explanation than this, i'd like to hear it...

ekkk the onli thing we know about dark energy is it oppose gravity. in my 2nd post in this topic i already mention it.  why u need conclusion for the most basic thing? we are going backward

remember this. first: dark energy do repulsion process. second: it make the universe expand. third: gravity weaken due to dispersing matter(when universe keep expanding) so 'suddently' dark energy which still maintain its energy density able to accelarate the expansion process.

fourth: nobody know. and i also should include zero, when universe start to distribute it content (to dark energy, dark matter and ordinary matter) especially during inflation time but we still unclear what happen then. as they say, no GUT(grand unified theory) no glory..

aku_EnSeM

i'm not workin for another name, but i just wanna know that can dark energy represent some sort of negative energy? workin for another name is foolish...

yea.. if the only thing we know is that it opposes gravity, then why couldn't we xtend it to the possibilities that dark energy might contribute to negative gravity? in which it pushes things.... then it might also represent some sort of negative mass with negative energy? if this conclusion goes smoothly, then why cant that premise be true?

sometimes, scientists struggle most on the basic things... for example, newton worked tediously on the equation of gravity... yes, it xplains a bunch of phenomenon... it xplains why the earth revolves around the sun... he sought for data, and they agree with his gravitation law... in the end, people ask... what is gravity, actually... how can the sun know that the earth is there? is that what u mentioned by going backward? there is nothing wrong of going backward... students in universities always go backward and perhaps, this would cause their lecturers to be suddenly speechless on the stage...

so, my focus is... can dark energy be negative energy? if not, end of my question.

[ Last edited by  aku_EnSeM at 29-7-2007 06:36 PM ]

cipanbakar

the problem is i dont know wat kind of negative energy u r looking for. can dark energy be negative energy? wat u mean 'be'? conversion? convert to negative energy? and wat is negative energy? is it just the term or what?

if a pushing property can make u call it negative, then just call it as u want! as simple as that

aku_EnSeM

no.... even me, mysolf dont know what am i talking about... that is why i ask for your... permission? or perhaps, clarification is better...

now, from newton's law, the gravitational force has negative sign in front of it.. but, if we make one of the mass be negative, then the force would become positive, we have repulsion force... why cant this be the cause of the expansion of universe...

also, if we have negative mass, then we have negative energy in accord to e=mc^2... so, why cant this negative energy be the cause of the expansion of universe..

then, in previous post, u said that dark energy is the cause of this expansion... so, why cant dark energy by negative energy? the term 'negative energy' here is just playing with the sign of an unknown.... if no one has the answer, and actually negative energy really does not exist, where is the spoil on the above premise? that is what i lookin for....

from ur answers, i reckon that there is no such term as negative energy nowadays....... and at the instant i typed that words, u said that i am playing with language with no physical significance....

an author of a book wrote 'we put negative sign in front of the newton's gravitation equation because it is an attractive force'.. it is not as simple as 'saying that attraction is negative'....

if the negative energy is wrong while it matches the mathematical expression, i seek for an explanation of where did the premise make mistake.... when if there is no mistake, i seek for explanation of why negative energy cannot exist....

as i type the above, i sense that you dont believe in the imaginary time proposed by stephen hawking, do you? and you have also proved yourself that u dont believe in the 95% probability of the universe to suddenly pop out.... it doesnt matter... they exist because of mathematical equation, as how dark energy came into existence in human's mind.... its pure mathematical.... but we can actually find another way to explain it physically...

okay, i did not play with words... i play with mathematics.. if dark energy cannot be negative energy, it must be positive.... then it would somehow create a mechanism in which it is powerful enough to counter gravitation... however, it must also be proved that why this positive energy does not create gravitation as well.... things get complicated...

in the end, if you have never encountered negative energy before, i assume that nobody has ever attempted to explain it in that way... 2 things occur: i am totally out of my mind, or something has to be discovered....

the end

[ Last edited by  aku_EnSeM at 29-7-2007 09:29 PM ]

cipanbakar

lenkali orang tanye tuh explain la betul2. dah penat aku tanye baru nak citer..

aku_EnSeM

nk xplain ape?? dh haku x tau...

Atomic_Omnikid

pening haku baca semua tuh,,,

aku_EnSeM

haku pong penin gak... haku x tau ape haku cakap...

ussopp

aku pening gak laa...takpe digest dulu...

aku_EnSeM

dah habes dah

Alam ini teorinye terdiri dari dark energy; dlm 73%...dark matter; dlm 23% dan matter; dalam 4%...dark energy dan dark matter masih jauh untuk di fahami ...(observationally)..sebab itu di gelar "dark"..so actually "observationally/experimentally" sehingga kini kita cuma boleh faham hanya 4% je dari alam ni...our physical material universe....subatomic quarks sampai ke galaxies..its clusters ..objects up to 15 billion tahun cahaya macam quasars. Dengan perkembangan fizik teori terkini dalam ilmu theoretical physics seperti M-theory ..mengatakan alam ini "more than meets the eye" (ala ala transformer )...ada alam di sebalik alam....alam yang kita hidup ini umpama sehelai lembaran (membrane) yang terapung apung di dalam ruang berdimensi tinggi (di gelar "bulk")......di mana tidak mustahil ada banyak lagi membrane2 (alam2) yang terapung...jika sekiranya membrana ini collide sesama sendiri....BOOOM!...kiamat alam....so pratically adalah mustahil untuk predict bila kiamat (kalau big crunch atau big rip kita boleh predict the expansion pattern)...kadang terasa fizik sekarang semakin ke arah metafizik...