Dark Matter & Dark Energy - Page 8

[jasimp]

Underwater cities would probably provide protection. Of course there is the problem of running out of food. What would be helpful is if we could create a very reliable source of fake sun to grow crops underwater. Then we could live there and be safe from lots of natural disasters, and gamma rays.

[Lardmeister]

That would only be possible for a few lucky folks, not 6 to 10 billion earthlings. With gamma rays heavier atoms like lead or gold would be better shields.

[jasimp]

I was joking around, however on a more serious note 4 inches of water can provide protection, about 10 ft should be enough to block most of them but, like you said, lead provides the most protection, about 1/4 inch stops almost all of them. It would not very practical to cover houses in lead. Especially becasue of lead poisoning. Maybe if cities had underground caverns and tunnels with lead sheeting on the top we would be protected. Food would still be a problem though.

[world_weapon]

Maybe if we find a new more profound method to play around with photons aka electromagnetic radiation wich can handle the levels of radiation associated with gamma rays, maybe we can actually reflect them or even absorb them for some use. Im sure by that time, we will be able to float around in space on the starship enterprise. LOL, jk, well sort of. It can be assumed that gamma rays like other types of em radiation could even possibly be used to transmit information. In fact, maybe it already does, but what it says or what the information would mean to us, is probably beyond the scope of mankind's intentions. This is a little subatomic, so I am thinking that maybe playing more with atomic arrangements could lead to an answer. What about carbon nano? Hmm, a few years back, almost a decade ago really, I read about carbon arrangements that could perform the same functions as circuits with the electron, maybe there are some complex arrangements that would allow us to do things with photons from ranges that would normally be too powerful, or extremely weak. Hmmm, nano solar cells? The kind that work in the dark? Who knows, lets see what the next hundred years will have to offer.

[MidiMagic]

It is impossible to travel at the speed of light but if you could then your time would be slower than the time around you.

If you could travel at the speed of light, your time would stop. That's why photons don't decay.

[jasimp]

It would stop compared to the time around you. But to you it would still be moving.

[Lardmeister]

Looks like one of us simply has to bite the bullet and travel at the speed of light to see how it comes out!

On the gamma ray issue, we still have about 50 million years for next massive burst to statistically happen. That is, if statistics can be believed.

[jasimp]

Someone I know is a statistician and they are usually right. Two days before a big snowstorm he said that he was going to have to take the day off because his kids were going to have a snow day; a 100% chance according to him. It ended up being the only snow day that whole winter. However, two days is a lot different than 50 million years.

[bumsfeld]

One should be able to change gamma ray energy into alternate energy, similar to light striking solar panel. Gamma ray burst might overpower the device dependig on the design.

The Russians used to make batteries for satellites that used radioactive decay (gamma ray, xray, etc.) as source of energy.

Is dark energy simply invisible/undetectable with present day technology?

[jasimp]

Time is not an absolute measure but is different for everyone becasue time is affected by gravity. The stronger gravity is the slower time goes. The difference is very small, a clock on the suns surface would go only about one minute slower than one on the earths surface. Our biological clocks are also affected by gravity.
Dark energy was postulated to account for tiny ripples detected in bacround microwave radiation. The ripples indicated that the universe might be flat, the third Friedmann model. There was not enough matter or dark matter to account for this so they said that an undetected substance called dark energy might exist. Dark energy has never been observed while dark matter has.

That would show that it is undetectable with present technology.

[bumsfeld]

Thank you muchly jasimp! Oh, I see, dark energy has never been knowingly observed, other then maybe in the spiritual world.

[EnderX]

I was joking around, however on a more serious note 4 inches of water can provide protection, about 10 ft should be enough to block most of them but, like you said, lead provides the most protection, about 1/4 inch stops almost all of them. It would not very practical to cover houses in lead. Especially becasue of lead poisoning. Maybe if cities had underground caverns and tunnels with lead sheeting on the top we would be protected. Food would still be a problem though.

Where are you getting your values from? From what I've read, I was under the impression that lead can stop Beta radiation, but that it took several feet of concrete to stop Gamma.

[jasimp]

Seeing as there is relatively no information on what would be sufficient to block gamma rays from the magnitude of what would come to us from space, I stated figures that block gamma rays that humans can produce. Sorry I was in a rush and forgot to post what those numbers represented.

http://www.stmary.ws/physics/gamm_1.htm

[bumsfeld]

Heavy water (deuterium oxide) is used in French nuclear reactors, and is very good in quenching gamma radiation due to the larger nucleus.

[GrimJack]

It is not an easy calculation to make - http://tinyurl.com/29l8wm - a simplification is "Unlike charged particles, a certain percentage of gammas will always make it through the absorber and it is useful to consider the half-value thickness of a given absorbing material for the gamma ray energies of interest" -- no matter how good your shield is, some is going to get through.

[Lardmeister]

This was just in the news, a massive burst of radio wave energy was observed for the first time coming from space, about 3 billion lightyears away.

Dark energy? Speculation is that it comes from the evaporation of a black hole, where extremely dense matter evaporates to energy. There are a few things physics can not easily explain as of this time. Maybe a government grant will help!

[EnderX]

No thank you. If government gives money to the researchers, then things tend to go off in inappropriate directions.

[jasimp]

what do you mean "things tend to go off in inappropriate directions"?

[EnderX]

Governments like results for their funds. Scientists who draw on the governmental dole are more likely to become monofocused on only one possible cause/result to their research than scientists who do not, because what in the business world would be called risk (looking at multiple possibilities) is considered in the governmental world to be 'waste'.

Example: There is a theory about cancer causation that assumes the cause is not gene mutation, but over-abundance of chromosomes, most likely introduced during cell division when the chromosomes are somehow not divided evenly. Not all cancers are linked to mutagenic diseases; from what I've seen (and I admit to not being a cancer researcher, so I'm going on the material I've read), most cancers are, however, aneuploid. (I may have misspelled that. The term refers to the extra chromosomes.) Some human cancers are known to have around 80 chromosomes per cell, as opposed to the 46 of a normal human cell.

Why do I bring this up? Because most likely, government-funded researchers will never do any research in this direction; that would imply that the money being spent on the mutagenic theory of causation was wasted, which would be a Bad Thing for the researchers and their financial backers in the government.

[jasimp]

I see, thank you for clarifying.

[vegaseat]

For a black hole to evaporate energy it must be spinning rather rapidly (quite possible). This in turn established a very strong magnetic field along the axis of the spin, offsetting gravity enough to allow some forms of energy to escape as a beam along the axis points. Sort of like shining a focused laser beam into space. To catch a glimpse of this energy beam as it scans across space from 3 billion light years away would be very lucky.

Mysterious or dark energy is a good name for these kind of somewhat spooky phenomenon.

[Lardmeister]

Wow vegaseat, that is heavy talk! You mean if energy is in a narrow beam, you can't observe it unless you are in the target or it hits a target? The energy is there, but is invisible or dark.

[GrimJack]

This just in:

A study of small galaxies circling around the Milky Way founnd that while they range dramatically in brightness, they all surprisingly pack about the same mass. The work suggests there is a minimum size for galaxies, and it could shed light on mysterious dark matter.

Spinning around the Milky Way are at least 23 pint-sized galaxies, each shining with the light of anywhere from a thousand to a billion suns. Though each of these galaxies is very dim compared to large galaxies like our own, they span a large range in brightness.

Astronomers led by Louis Strigari of the University of California-Irvine studied the movements of individual stars in these satellite galaxies to determine the mass of each galaxy.

"What we found was astonishing, which was that they all had the same mass," said researcher James Bullock, a UC-Irvine astrophysicist. "It's not what we were expecting — we were really taken off guard."

Loaded with dark matter

The finding could help explain the mysterious stuff called dark matter and how it affects the formation of galaxies. Nobody knows what dark matter is, but its presence is revealed by gravity that is not produced by the regular matter that can be seen.

Despite their wide-ranging brightnesses, all of the 23 satellite galaxies around the Milky Way seem to have a central mass of 10 million times that of the sun. And what's more, almost all of that mass seems to be made up of dark matter, with just the tiniest smidgen of visible matter producing stars.

"These are by far the dimmest galaxies that have ever been discovered, and the least luminous of these things are the most dark-matter-dominated things that we know about," Bullock told SPACE.com.

Though they qualify as galaxies, the satellites are not pinwheel spirals like the Milky Way and its cousins. Rather, these dwarf galaxies look more like diffuse, puffy balls of light.

Link here

[GrimJack]

I was going to put this in my geek thread but since it is really about dark matter, well - here is a geek rap about looking for dark matter.

[Lardmeister]

I was going to put this in my geek thread but since it is really about dark matter, well - here is a geek rap about looking for dark matter.

Thanks GJ, that makes science simple enough even I can understand it! May the Superior Omnipresent Being bless you!

[sneekula]

This thread should be called:
"God's Matter and God's Energy"

[jasimp]

No. It shouldn't.

[twomers]

>> I was going to put this in my geek thread but since it is really about dark matter, well - here is a geek rap about looking for dark matter.
That made me cringe, but like a car crash, I couldn't stop watching it.

>> "God's Matter and God's Energy"
Not until it's proved.

[ConradMc]

Hey um.... How do we know dark matter exists if we do not have any way to measure it?

Dispite not being able to see dark matter, much like many other physical 'objects', we can see the effects. Say, for example, a star 50 light years away exploded. Normally, all radiation, including light would travel through the 4 main dimensions of spacetime at a controlled rate in near linear patterns (excluding problems caused by large gravitational sources) out in every direction. Some of this would travel towards the earth, but most away from us. However, say this light encountered "dark matter" along a different route, its properties would bend and shape the light, and could send it towards the earth. This way space observers could observe the same event happening 10 years apart, because dark matter interfered with another path of radiation.

Dark matter also helps us to figure out locations of Black Holes, and various other properties of space based on its lens like effects.

[sneekula]

Well, if you can observe it, then it wouldn't be dark matter.