One imaginative science fiction short story I read had an Earth-made probe travelling for thousands of years with sperm and eggs cryogenically frozen then upon reaching a habital world, the ship auto lands and machinery/computers essentially grows and educates the young human children.
That's assuming the light barrier can't be surmounted.
Just my opinion but even if an extremely more intellegent alien somehow could travel at the speed of light the possibilitys of them reaching earth would be slim to none.
1) can they live thousands of years in order to make the trip even at light speed?
2) could they find us?
3) why would they bother?
I would guess a supreme being on earths future could figure out time travel before an alien from another star system could visit us.
If time travel works, but faster than light doesn't, it's simple.
Put a time machine onto a slower than light starship. Get on board. Point the starship at your destination. Get in the time machine. Go forward in time to when the starship reached the destination. You are now at your destination.
Depending on how the time machine works, you can even take it off the starship, and go back in time, so that you can be on the new planet at (or before) the time you left for it in the first place.
But I wonder how a time machine would work if it was also going at a fraction of the speed of light, considering that time would move differently at that speed. If I were to guess, I would say that the time machine would likely have to be kept at a constant speed during the time it is used, or your calculations would get thrown way off.
I didn't know that, seems every program I see they conclude the big bang started as an extremely hot and dense particle smaller than an atom that basicly blew up 13.7 billion years ago and expanded to what we see today.
I'm far from a scientist but my pea brain just can't except some of this.
Where did the dense particle come from?
How old was it before it popped?
If hubble can see a galaxy 13.7 billion L-years away surely the big bang didn't instantly create galaxys...don't they take billions of years to form themselfs? Hubble could be looking at a galaxy 13.7 L-years away that formed 20 billion years earlier.
I don't think that's an accurate description of current thinking on the "big bang" and most scientists don't really consider that name to be very accurate. I don't think I could do justice to describing the current state of the theory (while I am a scientist, I am not a physicist) but generally I think it involves a singularity, not a particle. Also, the estimated age of the universe is based on multiple lines of evidence including things like background radiation and I'm under the impression that physicists think they've got it down fairly accurately. I've read a couple of related books recently (Universe from Nothing by Lawrence Krauss and the Grand Design by Stephen Hawkings), but even reading those I find it hard to really get my head around some of the current science on the origins of the universe.
Space enthusiasts will be able to watch what NASA calls "seven minutes of terror" on Sunday when the space agency broadcasts live the Mars landing of its rover Curiosity.
The landing is expected to take about four and a half hours: The broadcast starts at 11:30 p.m. ET Sunday and runs until 4 a.m. ET Monday. The exact touch-down time is scheduled for 1:31 a.m.
If the mission is successful, viewers will be able to see Mission Control receive its first signal from the rover on Mars.
The broadcast will be streamed on NASA TV, on the agency's website, nasa.gov.
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Space enthusiasts will be able to watch what NASA calls "seven minutes of terror" on Sunday when the space agency broadcasts live the Mars landing of its rover Curiosity.
The landing is expected to take about four and a half hours: The broadcast starts at 11:30 p.m. ET Sunday and runs until 4 a.m. ET Monday. The exact touch-down time is scheduled for 1:31 a.m.
If the mission is successful, viewers will be able to see Mission Control receive its first signal from the rover on Mars.
The broadcast will be streamed on NASA TV, on the agency's website, nasa.gov.
YES YES YES YES YES!
This thread is awesome.
What has me so excited is not that this is yet another probe on Mars, but that it's a stepping stone for landing larger technology on planets and moons in orbit.
In my mind, the existence of extra-terrestrial life is a foregone conclusion, finding proof of life on another planet jazzes me up, but not as much as the idea of technological advancements that allow humans to colonize regions of space.
Once you can land a multi-ton object on Mars or Titan, maybe you can send robots that can build pre-fabricated structures.
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finding proof of life on another planet jazzes me up
Don't be disappointed if they find no evidence on Mars, after watching a program on the subject recently even if life was like humans there it only takes a few hundred thousand years for all evidence to be gone. Even fossilization would be extremely unlikely on a dead planet, best you could hope for is a trace fossil (ie..footprint) but the chances a slow moving rover would find one would be like finding a needle in a million haystacks.
The only real chance of finding former life would be hoping that microorganisms froze in the water before the planet went dead and they find that bed of ice.
I don't think that's an accurate description of current thinking on the "big bang" and most scientists don't really consider that name to be very accurate. I don't think I could do justice to describing the current state of the theory (while I am a scientist, I am not a physicist) but generally I think it involves a singularity, not a particle. Also, the estimated age of the universe is based on multiple lines of evidence including things like background radiation and I'm under the impression that physicists think they've got it down fairly accurately. I've read a couple of related books recently (Universe from Nothing by Lawrence Krauss and the Grand Design by Stephen Hawkings), but even reading those I find it hard to really get my head around some of the current science on the origins of the universe.
I have read a little about cosmic background radiation myself and I may have missed it but I can't remember anyone tying it into the age of the universe except for calculating the radiation temperatures. This has gone up alot from the first measurement in the late 40's till now. whats to stop it from still going up?
I also have read Lawrence Krauss and tried to read Hawkings but they still don't explain how they come up with the 13.7m old universe (it just is to them) How about the balloon theory? Krauss and Hawkings say it's true, in one breath they claim the expansion of the universe is moving everything apart from each other but in an other breath they claim galaxy's will collide (including ours in a few billion years)
I say take a balloon, draw dots on it,blow it up and show me a dot touching each other.
Sometimes I think these Scientists and physicists are just as dumb as I am when it comes to the cosmos.
I say take a balloon, draw dots on it,blow it up and show me a dot touching each other.
.
Why can't things be moving around inside a inflating universe though. From reading your post it seems you think everything inside the universe is in a fixed position while the universe is inflating. Just because things are getting further apart in general doesn't mean any 2 things might be moving towards or away from each other.
Why can't things be moving around inside a inflating universe though. From reading your post it seems you think everything inside the universe is in a fixed position while the universe is inflating. Just because things are getting further apart in general doesn't mean any 2 things might be moving towards or away from each other.
I'm not saying saying anything really..just looking for answers.
Your saying a bunch without saying really anything, are you a scientist in it for the money?(like most)
No offense but if your willing to open your trap at least explain your position...otherwise it's just drivel without answers.
The universe is expanding and that dominates at distances of galaxy clusters and larger but at smaller distances other forces dominate. The Andromeda galaxy is heading towards us because gravity is stronger than the expansion of the universe at that distance. Just like gravity overcomes expansion in our solar system and atomic forces overcome expansion in your body.
The balloon analogy is just an analogy. The galaxies as dots aren't connected to the balloon and other forces are at work, not just the expansion.
The big bang theory describes the history of the universe from very early (hot and dense) to now, it doesn't describe how the universe got to that state to begin with.
I'm not saying saying anything really..just looking for answers.
Your saying a bunch without saying really anything, are you a scientist in it for the money?(like most)
No offense but if your willing to open your trap at least explain your position...otherwise it's just drivel without answers.
Of course things move around inside an inflating universe. After all, it's not the galaxies and other celestial bodies expanding, it's the intervening stretches of intergalactic space where the force of expansion is powerful enough due to the lack of adequate gravitational force that is stretching. At small distances, other forces dominate (as photon said). It's why our atoms aren't ripped apart -- the electromagnetic force is far stronger. It's why the moon doesn't race away from us, and the Sun doesn't disappear as space expands at faster-than-light-speed (which doesn't defy special relativity, since nothing is travelling through space relative to other objects at superluminal speeds).
The Andromeda galaxy is a great example. It's rushing toward the Milky Way, and will collide and likely merge with our galaxy in the distant future. This doesn't contradict anything, however, as at those distances gravity is still dominant, and you don't need to worry about the effects of dark energy.
And if you think about it, as the universe continues to expand and the distances between celestial objects grows, the rate of expansion should grow, as well, as the force of gravity becomes weaker, and weaker. This, of course, relies on whether or not dark energy is constant, but it could explain the accelerated expansion of space they've noticed has begun around 7 million years ATB. Another explanation could be quintessence -- that the inflationary period hasn't ended yet, and we're still experiencing it.
As for how the CMBR is linked to the age of the universe, here is a link to a Wikipedia article that helps explain the Lambda Cold Dark Metter Model, which is what cosmologists generally use when trying to date the universe using the bang. Trying to explain all the ways the CMBR is linked to the age of the universe in here would enlarge this post by a lot, and, frankly, I couldn't explain all the mathematics. Basically, as you may or may not know, it's the residual heat left over from the start of the bang that was trapped for a while due to scattering by free electrons before the matter era (neutrally charged atoms were formed). It then escaped, but has had its energy reduced due to the expansion of space and the red-shift effect (its wavelength has been stretched out, making it less energetic and cooler). Scientists measure the peaks and troughs of the temperature of the CMBR throughout time, using advanced mathematics, and are able to come to conclusions that support other pieces of knowledge and evidence.
It's not foolproof, and it's not 100% fact, but it all works together remarkably well. The age of the universe used to fluctuate often in scientific circles two decades ago, but since the 2000s there has been a lot of consensus on the issue, and it's why you haven't seen the age being changed every other year or so like you used to.
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I didn't know that, seems every program I see they conclude the big bang started as an extremely hot and dense particle smaller than an atom that basicly blew up 13.7 billion years ago and expanded to what we see today.
I'm far from a scientist but my pea brain just can't except some of this.
Where did the dense particle come from?
How old was it before it popped?
If hubble can see a galaxy 13.7 billion L-years away surely the big bang didn't instantly create galaxys...don't they take billions of years to form themselfs? Hubble could be looking at a galaxy 13.7 L-years away that formed 20 billion years earlier.
I actually missed your post, whoops, and I think Ahsartus has already explained some of it.
The beginning of the universe wasn't a dense particle (I think you probably got this idea from Lemaitre, the Catholic priest that first came up with the idea of a "Big Bang," and proposed a kind of "superatom" made of an electron and a positron). Some scientists believe it was a singularity, some believe a fluctuation in a uniform inflaton field -- but -- no one will know for sure (or at least try to puzzle it out using science and mathematics) until a unified theory between quantum mechanics and general relativity is formed. The mathematics fail at that level at this point in time.
The Big Bang explains the evolution of the universe after whatever caused it to come into existence caused it to come into existence. Inflationary cosmology pushes this back some, and gives the bang a bang, but it still doesn't explain what brought the universe into existence in the first place. Inflationary cosmology explains how space expanded (the inflaton field -- a type of Higgs field -- got stuck on a peak in its potential energy bowl, expanded space in a manifestation of its negative pressure and thus repulsive gravity, and then created the first fundamental particles of the universe as it rolled down to a zero value), but doesn't explain why the universe was right for all that happen. The most common guess would be a statistical fluctuation, which wouldn't be such a big deal when you consider the low entropy of that stage of the early universe compared to if existence just popped into being now. But, really, that's just a guess at this time.
As for how old it was before the universe began, this might not even be a problem worth considering if time began when space inflated. If that is the case, the idea of "before" would be meaningless. There would be no before without time.
Hubble can't see all the way back to the beginning of the universe. Its successor, the James Web Space Telescope won't be able to either, though it will be able to peer back farther. The science of galaxy formation is tricky, and while scientists know many things about how it happens, there's a lot they don't. However, when they peer into space, they're able to see fairly uniform stages of galaxy formation. Like a house being built, they're able to look back and see it coming together. Of course, they can't look back all the way, and will never be able to look back to the very beginning of the universe, so there is always new loops being thrown their way, and it is possible that galaxy formation will be pushed back to have occurred at an earlier time, but that doesn't necessarily mean the age of the universe will need to be, too.
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Prof Mark Robinson, the chief scientist for the spacecraft's camera instrument, LROC, said in a blog entry: "From the LROC images it is now certain that the American flags are still standing and casting shadows at all of the sites, except Apollo 11."
The Arizona State University scientist added: "The most convincing way to see that the flags are still there, is to view a time series of LROC images taken at different times of day, and watch the shadow circle the flag."
but they still don't explain how they come up with the 13.7m old universe (it just is to them) How about the balloon theory? Krauss and Hawkings say it's true, in one breath they claim the expansion of the universe is moving everything apart from each other but in an other breath they claim galaxy's will collide (including ours in a few billion years)
