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+ - Jupiter destroyed 'super-Earths' in our early solar system->

Submitted by sciencehabit
sciencehabit (1205606) writes "If Jupiter and Saturn hadn’t formed where they did—and at the sizes they did—as the disk of dust and gas around our sun coalesced, then our solar system would be a very different and possibly more hostile place, new research suggests. Computer models reveal that in the solar system’s first 3 million years or so, gravitational interactions with Jupiter, Saturn, and the gas in the protoplanetary disk would have driven super-Earth–sized planets closer to the sun and into increasingly elliptical orbits. In such paths, a cascade of collisions would have blasted any orbs present there into ever smaller bits, which in turn would have been slowed by the interplanetary equivalent of atmospheric drag and eventually plunged into the sun. As Jupiter retreated from its closest approach to the sun, it left behind the mostly rocky remnants that later coalesced into our solar system’s inner planets, including Earth."
Link to Original Source

Comment: Re:We suck as a people (Score 1) 28

by green is the enemy (#48636099) Attached to: Kepler Makes First Exoplanet Discovery After Mission Reboot
But this is not just another exoplanet. It's the Kepler spacecraft being back in business. I think that's news-worthy. By looking at many different patches of sky they will detect many more exoplanets. The only downside is that they won't be able to observe each patch very long, so only short period planets would be discovered. That's still lots of valuable scientific data. The way they precision-point this telescope now is also interesting.

Comment: Re: No surprise (Score 1) 224

by green is the enemy (#47944535) Attached to: Study: Chimpanzees Have Evolved To Kill Each Other
Why say this? Nature isn't intelligent, so can't define concepts like "right and wrong". However, it's not hard to propose a simple definition that applies to nature: a behavior is "right" if it's beneficial to the species' survival and prosperity, and "wrong" if harmful to the species. This may be somewhat different from some ethical philosophies, but not entirely incompatible. Human population density has increased significantly above that for which we evolved, and we no longer compete for food. This is a case of natural violent tendencies being "wrong", impeding the prosperity of the species. However, violence may be "right" for chimps that still compete for food.

Comment: Re:$230 isn't the problem (Score 1) 611

by green is the enemy (#47721389) Attached to: Study: Ad-Free Internet Would Cost Everyone $230-a-Year
I found myself willingly paying a $6/month subscription to a website (this surprised me quite a bit): Their model is very interesting. You do not pay for content, but with subscription you get more bandwidth and generally smoother access to their content (video), as well as wiki editing ability, unlimited "mylists", time shifted "live broadcasts"... basically just better service and perks, but not more content. They also run the "related products" ads below the main content, but with a twist: all "related product" links are user-submitted. It's actually fun to browse those.

Comment: Re:A little behind the times (Score 1) 315

by green is the enemy (#47630481) Attached to: Why the "NASA Tested Space Drive" Is Bad Science

Yes, the paper handles the vacuum issue very badly (Sections II and IV contradict each other, and Figure 22 says "(In 750mm Air)"). However, convective air flow is unlikely to be the cause of the anomalous thrust. I would expect convection to have a slow time constant as objects heat up and cool down, but the thrust turns on and off quickly in the paper.

I would like to see more plausible causes of the anomalous thrust. Any new physics discovery is extremely unlikely here, but so far the proposed explanations have been lacking.

Ionization of air might be one such possibility. The very high-Q cavity with tens of watts of input power may reach electric fields strong enough to ionize the air inside the cavity. The ions/electrons/air would need to escape the cavity somehow to produce thrust.

Comment: Re:They used a vacuum, and a serious one at that. (Score 1) 201

by green is the enemy (#47606561) Attached to: NASA Tests Microwave Space Drive
There is another clue in the paper: In the lower right corner of Figure 22 it says "(In 750mm Air)". So at least the tapered cavity test article was not run in a vacuum. However, it is reasonable to read that that their earlier tests with a pillbox cavity were done in a vacuum. You'd have to agree that they were sloppy in specifying the exact conditions under which each test was performed. I'm looking forward to independent tests of this concept that are undoubtedly coming given the publicity this received.

Comment: Re:They used a vacuum, and a serious one at that. (Score 1) 201

by green is the enemy (#47601865) Attached to: NASA Tests Microwave Space Drive
Someone made this paper available for download. Their writeup makes it seem like they perform the experiment in a vacuum, except for one tidbit in the "Summary and Forward Work" section:

Vacuum compatible RF amplifiers with power ranges of up to 125 watts will allow testing at vacuum conditions which was not possible using our current RF amplifiers due to the presence of electrolytic capacitors.

This makes it sound as if these tests were not conducted in vacuum after all...

Comment: Re:Sensationalism at its worst (Score 1) 201

by green is the enemy (#47587069) Attached to: NASA Tests Microwave Space Drive
I haven't seen this vacuum issue addressed by anyone after some searching. To me it seems premature to speculate about quantum vacuum effects when interactions with air seem very likely. Perhaps they planned to perform these experiments in a vacuum, but didn't quite get to that point when the abstract was due? At this point, they may have finished the vacuum version of these experiments, so may have some results to present. If someone does know, please pitch in.

Comment: Re:The one good feature of ARM (Score 1) 108

by green is the enemy (#47498191) Attached to: A Look At NASA's Orion Project
Can you point to good criticism of the Asteroid Redirect Mission? I can't think of a better way to kick-start in situ space resource utilization, which is what we need for sustained human presence in space. Perhaps you mean the manned portion of this mission? The redirection of an asteroid into a close orbit is a very good idea by itself. Of course, spacecraft sent to study this asteroid and try extracting resources from it should mostly be unmanned (and will be).

Comment: pigs (Score 1) 667

by green is the enemy (#47497959) Attached to: Russian Government Edits Wikipedia On Flight MH17
All sides in this are acting like pigs, the Russians, Ukrainians and the Ukrainian separatists. The Russians are and the separatists are throwing around unsubstantiated accusations. Even the Ukrainians are not releasing the volumes of radar (including military radar) and air traffic control data that surely exist. The worst ones are of course the ones who shot at the plane. Since they are hiding and spewing misinformation, it's obvious they are not even a tiny bit sorry for accidentally shooting down a civilian plane. Their behavior makes it look like the plane was deliberately targeted, truly a work of evil.

Comment: Re:Some more info: (Score 1) 752

The people talking in the background say that the plane exploded in the air (big explosion) and debris was still raining down as the smoke was just starting to come up from the ground. They also mentioned "it's a good thing they brought it," pretty obviously referring to an anti-aircraft missile system.

You are lost in the Swamps of Despair.