wallflash

True, but this "everywhere" would be in one infinitesimally small and dense point if it began from one singularity.

The bolded is what I have always understood. But this point seems to be disputed now, unless I am misunderstanding some of the responses here. ( again, certainly a possibility )

OK , now I am confused as well . Everything I have ever read ( as a layman ) has made the point that everything in the universe is moving away from everything else due to expansion from a single point, so that nothing is moving towards anything else, excepting local gravity effects like our solar system . One physicist even makes the point that at some time in our future humans will know about other stars only through historical records, because all of them will have receded beyond the point at which light can reach us, coupled with the expansion of the universe at a faster rate that light can cross the expanse ( barring technology that will overcome this problem ). I have read theories debating whether the universe will continue to expand into a lifeless collection of cold dead stuff in the way off end of the universe as we know it, or whether there is enough mass to reverse the expansion and pull the universe back into a single point in what is termed the Big Crunch. While the expansion of everything away from everything else may not imply a single singularity at one point in the universe, the Big Crunch idea seems to, unless I am missing something ( which is certainly possible).

Im not sure what their concern is, the object being pointed at or the users hand holding it. http://www.skyandtelescope.com/observing/some-pointers-on-the-use-of-laser-pointers/ Under a "buyer beware" warning, they write A second concern emerged even earlier, in 2010, when four NIST researchers found that poorly made green laser pointers can emit harmful levels of infrared radiation. These laser pointers generate a collimated beam of infrared energy that's converted to green light when it passed through a special crystal. In most units, a combination of coatings and filters keeps all the infrared energy confined. But the researchers found that really inexpensive green lasers can also lack an infrared filter altogether. One tested unit was so flawed that it released nine times more infrared energy than green light.

I am looking to buy an inexpensive green laser pointer to take camping and use to help show my grandson the constellations . In reading on them I have read that some cheap ones can emit dangerous levels of infrared radiation. In just browsing there looks to be some decent ones in the $50 range , if these are not the ones being referred to as dangerous. Any recommendations on a known safe laser pointer in the $50 range that are decent enough to point out constellations on a clear night?

Im not sure what you mean by "just a model"? Experiments were done to see if in fact our universe is a projection of data from 2D sphere surrounding the visible universe. You seem to suggest that the idea is just some tool of some sort that isnt meant to be taken as reality, but just a way to explore deeper into the physics of our universe. The experiments suggest that the idea that we are in fact simply projections of data from a 2D universe was taken seriously by the experimenters, and not merely a tool for mental experiments. http://blogs.discovermagazine.com/d-brief/2015/12/08/reality-check-the-universe-is-probably-not-a-hologram/

I get that part. My question is more long the lines of 'is there any logical reason to suspect this is this case'? We have reasons to suspect DM and DE. We have reasons to suspect there is a 9th planet ( or 10th, I prefer 10th) we havent spotted yet . We had reason to believe in the Higgs boson. So is there some evidence or observation that serves as a logical segue into suspecting the universe is a hologram? Or is it more of a shot in the dark, something thought up while leaning back in your chair after yet another failure, running your hands through your hair in frustration, and after clasping them behind your head to lean back and consider yet another failure you think "well, maybe we dont need 11 dimensions,maybe its just 2 and the rest is just a hologram" ?

What causes science to speculate about the possibility we are a holographic universe? All other strange ideas have some reasoning behind them. We suspect dark matter because the universe doesnt act as expected based on visible matter. We suspect dark energy because the universe is expanding , and doing so faster than we can explain. But a holographic universe? What suggests this? Is it just a stab in the dark because other ideas like string theory are not coming through as hoped? Or is there some unexplainable observation that we think might be due to our universe being a holographic one?

I have a question on these issues I have never seen addressed as a whole . We believe in the probability of dark matter because the universe hasnt flown apart, but there isnt enough visible mass to account for the necessary gravity to prevent this. We believe in the probability of dark energy because something is driving the universe apart at an increasing rate, yet we cannot see this energy. These seem almost like contradictory statements. We believe in DM because the universe HASNT flown apart, yet we believe in DE because the universe IS flying apart and eventually every galaxy will be too remote to see any other galaxy in the universe. What is the solution to this? I suspect maybe that it has something to do with the universe should have already flown apart by now if this dark matter doesnt exist, so its a time frame issue, but I have never seen in anything I have read where the concepts of needing dark matter for sufficient gravity to prevent the universe flying apart and dark energy to explain the increasing expansion dealt with simultaneously as a whole. An explanation for the scientifically interested but mathematically challenged laymen to understand would be appreciated.

Naw, I thought I would ask a question just so I could ignore the answers

OK the Slinky thing is cool. My question on that would be, does the fact that its coiled and not stretched taut and essentially out to its limits have any impact on that? Obviously if you did the same thing with a cable and a 100 lb weight, the weight at the bottom will appear to move at the same time as the cable is released, and not wait for the top end of the cable to reach it before moving downward . Do the coils cause the delay entirely, or merely accentuate the delays for human eyes to notice? Lets replace the space station in my scenario with a powered spaceship pulling against a tether, so that we are not dealing just with inertia. What keeps the spaceship from instantly moving even a quarter inch to trigger the laser when the tether is released at Earth level? We are not talking about a transference of energy up the cable, as we would be if we were moving the cable to create a wave action along the cable. We are simply removing an action at one end . Its hard to conceive that the ship at the other end pushing to move away would remain motionless even though there is no longer any restraint upon its movement, especially that we are now talking about it remaining motionless for around a minute with a powerful engine trying to move it with (now) no actual restraint, instead of 3 seconds. Or to go back to the gravity beam, so that we are not dealing with pressure waves . If this beam is simply ended at Earth level, what keeps this ship motionless for 3 seconds with the actual restraining force removed?

OK, I'm new here, and not a college educated guy or one with any professional connection to science or teaching, and don't have the math background to grasp the equations of physics and astrophysics. Just someone interested in astronomy and astrophysics, as well as some others like evolution. But I have a few questions I would like to run past posters. I've seen some things said in books like Brian Greene's The Elegant Universe that seem more guesswork than solid proof, and the following comes from this sort of "it just has to be" mentality that I see in some of Greene's explanations. The following has to do with the relay of information faster than the SoL, or the premise that none can be. Imagine that in our future scientists have tethered a small space station to the Earth at a distance of 558,000 miles from Earth . This can be done by a physical cable or some future gravity beam. So after a few orbits the space station assumes constant velocity and maintains a position straight up from the tether point. They also place a second space station at a distance from Earth of 1,860,000 miles in a stationary position relative to the Earth, so that the view of the Earth is always the exact same spot in the monitoring screen, and the distance from Earth to the second station and the first station to the second station are identical. So the first station is 3 light seconds away from Earth, and the second one is 10 light seconds. The scientists set up a laser signal that fires at precisely the time each day when the first station is at a 90 degree angle from a second station to earth axis, so that both Earth and the first station are visible and the same distance from the second station, and another beam from the first station to the second at this same point. Happens twice a day obviously. Tests are done to calibrate the beams to fire to arrive at the second station simultaneously. Once everything is calibrated, the experiment becomes this. The calibrating laser on the first station is turned off and replaced with a laser that fires the instant the station detects outward motion away from Earth as it is released from its tether to Earth. At the precise time the Earth and the first station are the same distance from the second, the tether holding the first station to the Earth is released at the Earth level, and simultaneously a laser is fired from Earth to the second station signalling this release. When the first station detects the outward motion of being cut loose from Earth, it fires its laser to the second station. The SoL physics (IF I understand them right ) say that the second laser will arrive 3 seconds after the first laser, because it will take 3 seconds for the first station to receive the info that it has been cut loose and fire it's laser to the second. This seems nonsensical. Am I simply misunderstanding something basic? If this is true, then what holds the first station in place for that 3 seconds before it detects it has been cut loose? It has instantly lost what holds it to Earth. What holds it stationary for a full 3 seconds after the release? You could stretch this to a minute with enough distance from Earth to station. It seems to me it should move the instant it is released at the Earth point , but if it does, isn't releasing it at the Earth level and having it react simultaneously 558,000 miles away a transfer of info faster than the SoL? If it doesn't move instantly, what keeps it in place for the 3 seconds after it has been cut loose?