Whether In case 5000 light years to be measure we have to wait for 10000 years !!!!!?How it is possible.
122786
The distances between stars is quite large .The general convention of Kilometers or miles cannot be used due o the large numbers that we would have to deal with .\nLight is defined to have a constant speed of 299792458m/s . This number is precise to the last digit .The distance trvelled by light in a year can be found using this velocity\nthe distance would be 299792458*60*60*24*365= a large number suitable to denote lage distances \nwhen we say that the distance is 5000 ly we do not wait for light to complete the  journey .We determine distances using a different method and then use the above number to find th distance
447920
just ask, it's not as if 10 years have went by. What's so hard about that?
160591
Eventually, I believe it probably will.  Whether this takes 50 years or 500 is something only time will tell.
248304
In short, you can't be 100% certain, but a very long term trend would have to break unpredictably for it not to be.  Read on for details.\n\nThere is, as you have pointed out, substantial evidence that the universe is expanding. To understand how we surmise that it is still expanding in spite of the "old news" effect (most of the measurements of expansion rely on light that left its sources hundreds of millions to billions of years ago) you need to understand some of the details of how we quantify the expansion.\n\nThe expansion rate is quantified in units of velocity/distance. The Hubble constant, for instance is generally expressed in units of km/s per mega-parsec (1 Mpc = 3.27 million ly = 3.086x10^22 meters).  The current value for the Hubble constant is ~70 km/s per Mpc by our most accurate measurements. This means that on average, for every megaparsec  of distance ***an object that is not gravitationally bound to our observation point*** recedes at about 70 km/s. \n\nWe can also estimate the rate of change in the Hubble constant.  For instance, as something made of mass (such as the universe) expands, its own gravity is fighting that expansion and slowing it down. It might not be enough to halt the expansion, or it might be.  This is the distinction between an open universe that expands forever, a closed universe that falls within its own Schwarzschild radius and eventually will contract, and a flat Universe that will expand forever but is slowing at a rate such that the expansion will halt at infinite time. \n\nWe find the change in the Hubble constant  by measuring the recessional velocity (from which you can find the Hubble  constant) for  more distant objects. The more distant, the longer ago the light left that object, permitting us to calculate what the Hubble constant was in the past.\n\nIt is this sort of data that has recently shown us that not only did the expansion of the universe not slow as much as expected for the given mass present, about 5 billion years ago it appears the expansion began to accelerate.\n\nBut what about today?  With all these data from sources that are millions to billions of light years away, how do we know that, say yesterday, it didn't stop expanding?\nWe don't know for sure, however we have measured the trends of the expansion over time, and those trends would have to change VERY dramatically due to some unanticipated phenomenon.  The universe's expansion over time follows a fairly simple relationship, and has followed it for over 13 billion years. When we look as close as a hundred million parsecs, there is a clear expansion that follows this trend.  The trend would have had to change suddenly and unpredictably, in fairly recent (cosmologically speaking) history for it to now be contracting.\n\nThis would be analogous to tracking a projectile flying from the muzzle of a gun for 30 feet towards a target.  We have taken into consideration wind speed, gravity, muzzle velocity and so far the course is precisely as we predicted. Then, with 6" to go something happens that causes the projectile to deviate from its course significantly.  Perhaps a bird falls out of the sky, or there was a block of glass in front of the target that we did not see. That is how sudden a change we would need to explain why the universe is no longer expanding if it isn't expanding today, when it WAS expanding just 50 million years ago at the end of a 13.65 billion year trend.\n\nSo, you are right.  It might not be expanding, however a far simpler interpretation of the data is that the trend we have observed over a billions of years time scale has continued for the last 100 million.
663818
From the physics point of view, our universe thus far is approximately 15 billion light years and expanding every second. Light year is the distance that light with the speed of nearly 300,000 Km/s travels in one year. This distance equals 9, 500, 000, 000, 000 Km (that light travels each year). Now, imagine how big our universe is!!\n\nAbout the second part, The space-time (space and time are inseparable) make our universe. They are both dynamic and the  fact that universe expands means both the space and the time expand. Now, in what do the space and time and our universe expand? This fact is not like other daily facts in our life, it is not possible to assign a place for space-time so that our universe expand in it. We cannot say there is something outside our universe because it is meaningless. These concepts are complex and require in-depth studies and deliberating.\n\nI hope these would be a little helpful...
360404
Imagine the average human life of about 70 years (hypothetically).\n\nMake a time line of that persons life of 70 years.  Just for giggles we will make the time line one meter long, for every year of this person's life.  So you have a time line that is 70 meters long.  \n\nLooks good, right.  70 years is almost three quarters of a century, which in perspective to us as humans, is a relatively long time.  \n\nImagine that somone could actually live for 7000 years.  Now, make a time line that is 7000 meters long for this second person.  This is our "extended time line".  \n\nThis 7000 Meter time line or 7 Kilometers is a rather larger distance in perspective to the first 70 meter line.\n\nNow imagine laying both lines down, parallel to each other in a clear open field somewhere and imagine looking down at the two lines from the sky.  \n\nOf course the shorter line is shorter, but compared to the longer line it will appear extremely small.  The small line may even appear to have ceased to exist when compared to the longer line.  \n\nDoes this help put in into perspective?\n\nKinda like having a single specific drop of water, going to the beach and dropping it into the ocean.  Now go find that specific drop of water that you released into the ocean.  It is still there, but compared to all of the other drops of water that make up the ocean, it is all but non-existent.
281559
it would take a million years to list that. just google it.
594070
No.\nAlthough,I can't prove that it isn't possible...however,science has it's flaws-millions of years ago certainly does sound extremely distant!
347236
it depends on ones perception of time,the universe may have ended already,but we exist in a dimension that does not recognize it.perhaps the universe as humanity knows it will never end...
457395
It's all theory, we don't know if (something) can exceed the speed of light. I would argue that time would be void at that moment, but again it's my theory. Interesting thought though.
347499
All it means is that we don't know everything. We've learned quite a bit in the short time since we developed written language and the scientific method, and the rate of learning is accelerating. We'll learn more in the next 10 years than we've learned in the last 100. We'll probably understand the nature of dark matter in the next 10-20 years, and I would bet long odds that it won't require any supernatural explanation.
123758
I'm sure you are spekaing strictly hypothetically, but don't forget the closer you get to the speed of light (c), the slower time moves around you.  So if you were to go like 90% of c for 1 year, more than 1 year would pass for everyone else.
303300
Just one doubt about your  theory,how do you know that only one big bang has taken place as you say that a second one is coming up???And tell me how you would accelerate something to the speed of light as the mass would become infinite.\nAnd according to your theory the total energy in the universe will go on increasing.You are stuck in a viscious circle!!!
518509
I hope that in 5 billion years. We have somewhat evolved beyond this planet. Besides we won't have enough land or fossil fuels to last the next five hundred. I can hardly imagine five billion years from now.
349852
Hmmmm, in the future you might be right, but I think the cost of sending anything into space is quite goppingly high at present - and until we can travel SIGNIFICANTLY faster than light, I'm afraid the ex-con would have died a fair few tens of millenia too early to note anything of value.\n\nEven our own galaxy (a teeeeeny spec in the universe) is roughly 100,000 light years wide. At 1000 times the speed of light, an 18 year old criminal would need to live to be 118 year old just to see one side of our galaxy to the other. He would also be going a little fast to make the most accurate of observations.\n\nIt really is awfully big.\n\nInteresting idea though - and with suspended animation / faster than light travel it may one day be a plan.
420895
The people who said it is closer to 4.5 to 5 *billion* years, are correct.\n\nThe sun is a class G star, which has a lifespan of about 10 billion years (the main part of it's lifespan ... after 10 billion years, it expands and goes through a second, larger but shorter-lived phase).  The sun is about 4.5  to 5 billion years old, which means that it's about halfway through its main lifespan.   So it will be here a little bit more than it has been here already ... which is a *very* long time.\n\nIf the earth hasn't been physically destroyed by an asteroid, or some man-made catastrophe we cannot imagine yet, I am quite sure that life will still be going strong on the earth at that time .. but that humans will be long gone.   Either we will have left after making the planet uninhabitable for ourselves, or we will have killed each other off, or we will go extinct through natural causes (like an asteroid that doesn't destroy the planet, but does wipe out most life).  But in all cases, some life forms will survive, and will do quite fine without us.\n\nEven if we blew each other to pieces with nuclear weapons, and wiped out almost all life on the planet due to radiation, some life would survive the radiation (e.g. in the deep oceans) and life would eventually bounce back ... and would begin the process of evolution all over again.  That's what life does.
607903
You are correct!\n\nYes, depending on how far away the star is, we are looking at it as it was one million years ago (if it is 1 million light years distant). So, we are looking backwards into time, when we look out into distant space.\n\nThe sun is 8 light-minutes away from Earth...so if you are outside, and you can see the sun in the sky...it may have vanished five minutes ago, and we wouldn't even know it for three minutes!!\n\nThe quasars are the strangest of all objects in the universe. They are apx. 10 to 15 billion light years away from us...so that means that they are extremely ancient. Perhaps, they are as old as the universe itself.