【超光速引擎成真? 抵达火星只需10周】

#科技头条# 【超光速引擎成真? 抵达火星只需10周】美国太空总署NASA表示,准备公布其对于微波相对论引擎(EMDrive)的研究成果,该引擎通过让太阳能产生的微波在封闭的容器里不停反弹来产生能量推进,全靠电力而不需火箭燃料来运作,不仅能量损耗小,推进速度也极快,能够4小时到达月球,10周到达火星。尽管这个概念受到过"不符合物理定律"的抨击,近年来美、中、英等国的实验室都已经制造出了类似的引擎原型机。

It has been dubbed the 'impossible engine', that could take humans to Mars in just 10 weeks - but nobody knows how.
The so-called EmDrive creates thrust by bouncing microwaves around in an enclosed chamber, and uses only solar power.
Many argue the concept is simply hype, suggesting the design goes against the laws of physics , and now a Nasa lab that has been studying the concept is set to publish its findings for the first time it has been claimed.

The idea for an EmDrive was proposed in 2000 by a researcher named Roger Shawyer.
Since then four independent labs, including one at Nasa, have recreated the drive.
But the mysterious engine had baffled scientists because it appeared to violate the law of conservation of momentum, which states for every action there has to be an equal and opposite reaction.
This means the rocket can only accelerate forward if a force of equal magnitude is sent in the other direction - the rocket's exhaust.
Nasa's Eagleworks team is now ready to reveal its findings, it has been claimed - sending the physic world into a tizzy.
'It is my understanding that Eaglework's new paper has been today accepted for publication in a peer-review journal, where it will be published,' claims one user on the Nasa Spaceflight forum.
Earlier this year, an employee confirmed the team was working on the paper.
'The Eagleworks Lab is NOT dead and we continue down the path set by our NASA management.
'Past that I can't say more other than to listen to Dr Rodal on this topic, and please have patience about when our next EW paper is going to be published. Peer reviews are glacially slow,' Eagleworks engineer Paul March wrote on the same forum.
Earlier this year, a paper published in AIP Advances suggests the EmDrive produces an exhaust like every other rocket.

'EmDrive works just like any other engine,' Dr Arto Annila, physics professor at the University of Helsinki and lead author of the paper, told MailOnline.
'Its fuel is the input photons at microwave lengths.'
The researchers suggest the photons coming out of the machine interfere with each other, so that the overall effect seems as if nothing is there.
'In the cavity the input photons will bounce back and forth, and invariably some of them will interfere completely destructively.'

'Then the two photons will be exactly 180 degrees out phase.
'At the complete interference electromagnetic fields for the two photons will cancel exactly, but the photons themselves continue to propagate.'
The idea is the same as water waves travelling together, at the exact right time so that the crest of one wave is exactly at the trough of the other and cancelling each other out.
The water does not go away, it's still there. In the same way the pairs of photons are still there and carrying momentum even though they cannot be seen as light.

'The paired photons without net electromagnetic field will escape from the cavity,' Dr Annila said. 'This efflux of paired photons is the exhaust of EmDrive.'
'When the cavity is asymmetric, like the tapered cone, the efflux of paired photons is also asymmetric. Therefore the loss of momentum carried by the paired photons is uneven. In other words, thrust is non-zero.'
Dr Annila came up with the idea along with Dr Erkki Kolehmainen, an organic chemistry professor at the University of Jyväskylä and Patrick Grahn, a multiphysicist at engineering software firm Comsol.
'Thrust without exhaust is of course impossible,' the authors wrote in their. 'Yet, certain resonant cavities, when fueled with microwaves, deliver thrust without apparent exhaust.'
Their theory suggest the exhaust produced by the EmDrive is there, but just cannot be seen.
Dr Annila said the photons could theoretically be detected by an interferometer, the same instrument used to detect gravitational waves.
'My gut feeling is that it will be very difficult to detect such a small excess in energy density, especially when operating EmDrive steadily,' he said.
'Namely changes are more amenable to detection in any case. But still our idea about the exhaust can be useful to design the cavity for pairing photons better for an exit in a preferred direction, and hence to generate more thrust.'

原文链接:http://www.dailymail.co.uk/sciencetech/article-3764112/Is-mystery-impossible-fuel-free-EmDrive-thruster-solved-Claims-secretive-Nasa-lab-publish-paper-warp-drive-humans-Mars-10-weeks.html


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