coooool music :v
coooool music :v
I don’t agree on his claims. I would take a deeper look later …
In the light of the current warp field experiments by NASA I found this paper:
Could this actually lead to the creation of exotic matter or at least strengthen the case that a warp drive, or a least a warp field is possible to create?
general-relativity vacuum gravity spacetime
asked Mar 23 in Theoretical Physics by WolfInSheepSkin (-40 points) [ revision history ]
recategorized Mar 23 by dimension10
Is this really an ArXiv paper? When I follow the link it does not look like a standard ArXiv paper. Would you mind linking to the abstract page instead of directly to the PDF?
commented Mar 23 by Dilaton [ no revision ]
@Dilaton : Alright, I updated my question.
commented Mar 23 by WolfInSheepSkin [ revision history ]
Maybe this will help
see twistor’s answes on PSE.
how far did you study. Why are you thinking about warp drives? Do you understand the basic formalism of GR and Quantum field theory?
There seems to be some amount of work concerning negative energy using casimir effect, However I don’t understand the meaning behind such a thing. I have no idea about its application to worm holes either.
Kip thorne has written papers about these possibilities.
commented Mar 26 by Prathyush [ revision history ]
edited Mar 26 by Prathyush
+ 3 – 0
Hey, it’s that paper that’s always referenced on the standard Eric Davis presentation on wormholes! I don’t trust that guy too much because he writes a lot about aliens and psychic powers, but anyway.
Quantum effects, as well as some classical effects routinely violate almost every energy conditions that you can throw at them. So far quantum effects have been show to be able to break the trace energy condition, the strong energy condition, the weak energy condition, the null energy condition, the dominant energy condition, the averaged energy conditions and quantum inequalities (a good review here : http://arxiv.org/pdf/gr-qc/0205066.pdf). Those are of course all theoretical, though.
Here’s a little list of various effects known to violate some of them. I’m not at home so I don’t have all the papers in mind but I included a few :
Squeezed quantum states, and generally various superpositions of number states for free quantum fields. Those can indeed be produced experimentally (they are commonly used because they are useful for high precision interferometry), but whether or not they violate the null energy condition remains to be proven (their energy can be made inferior to the vacuum state energy, but what the absolute energy is cannot be determined without being able to detect gravitational effects). For informations regarding them, quantum optics book usually contain a good amount of details on them. Also :
The Casimir effect. While the Casimir effect is probably not best described by the commonly used explanation (metal plates are not perfect conductors and the Casimir is best fundamentally explained by QED loop contributions), the topological Casimir effect (where cyclical coordinates induce this) does have this explanation, and various instances of the Casimir effect (the usual one with metal plates, as well as more esoteric ones with domain walls) do seem to violate it. The same experimental problem to actually prove it applies.
Casimir effect from domain walls : http://arxiv.org/pdf/gr-qc/0205134v3.pdf
Energy density in the Casimir effect : http://arxiv.org/pdf/quant-ph/0504143.pdf
Gravitational squeezing. Various spacetimes force quantum fields into negative energy states at some points, most famously the Schartzschild metric with the Hawking radiation. Being a gravitational effect, this one cannot be tested experimentally so far.
Energy conditions using various definition of the vacuum in the Scharzschild metric : http://arxiv.org/abs/gr-qc/9604007 http://arxiv.org/abs/gr-qc/9604008 http://arxiv.org/abs/gr-qc/9604009 http://arxiv.org/abs/gr-qc/9703001
All manners of theories with interacting fields. Generally speaking, the most egreious violations of the energy conditions occur in interacting fields (which is the case for 2., 3. and 4.), because for the most part free fields are the main ones studied. In the case of the Casimir effect, it even violates the quantum inequalities, which is the one that is the least likely to be violated in general. Other examples in general are :
Scalar fields that are non-minimally coupled to curvature : http://iopscience.iop.org/0264-9381/19/19/309
Various studies for energy conditions in interacting models : http://arxiv.org/pdf/1502.01714v1.pdf
Various cheating effects. A lot of papers also make a variety of quantum fields more or less ad-hoc to study solutions. Among those are phantom fields (fields with negative kinetic energy).
In general if you want more informations about the topic I advise “Lorentzian wormholes” by Matt Visser and “Frontiers of Propulsion Science”. Don’t get your hopes up too much though. The existence of exotic matter is but one problem of all spacetime trickery and the White-Juday warp field interferometer experiment is a bit suspiscious.
answered Jun 18 by Slereah (130 points) [ revision history ]
Hi, Thank you Slereah.
commented Jun 18 by WolfInSheepSkin [ no revision ]
Are on the freenode irc physics channel??
commented Jun 18 by WolfInSheepSkin [ no revision ]
Skyping over troubled borders
(Originally published in Israeli popular newspaper “Yedioth Ahronoth”, November 5 2013)
Every day, thousands of Iranians and Israelis speak with each other online. The two of us just finished another Skype conversation. We spoke of plans to drive from Tehran to Tel Aviv using an electric car, of Islam and Judaism, and of the rising prices in the supermarket. More and more cross border conversations like these are taking place online. Our future, Iranians and Israelis, is no longer just in the hands of our governments. Until recently, direct conversations between the citizens of enemy states weren’t possible. If we wanted to “get to know the enemy”, we had to rely on articles published in the local media. Our conversations may still be illegal, in the strictest sense of the law, but nevertheless, the conversations are happening.
Our ability to speak with citizens of a different country, a country we are almost at war with, is changing world politics. In Iran and in Israel, in Pakistan and in India, in Morocco and in Algeria, the people of hostile states – the states are hostile, not necessarily the citizens – are talking to each other. And we, Iranians and Israelis, are at the front of this new world wide conversation. More than any other state in the world, the internet-based connection between Israelis and Iranians carries with it a hugh potential.
Iran and Israel are the countries with the highest percentage of net connected citizens: 40 million in Iran, more than half of them on Facebook, and almost 5 million in Israel, about 4 million of them on Facebook. In Israel, social networks play an important factor in national politics, and the Iranian blogosphere, the third largest in the world, is rich in political debates. The connection between the two is only natural. Using the internet, we can work together in so many fields: Iran has many young scientists, thirsty for international partners. world-class filmmakers. a buzzing technology scene. a diverse local culture with traditions unlike any other in the world. And yes, religious scholars too, doing God’s work. All of them will find surprising yet natural partners for joint projects in the dynamic, exciting Israeli culture, which also combines the religious the secular.
We, Iranians and Israelis, share many similarities: we strive to do great things, entrenched in an ancient and glorious past, fascinated by innovation and still practice old traditions. Our joint history is ancient: 2,500 years ago, under Cyrus the Great, we worked together. So great was our mutual work, that stories of it survived the storms of history, and the strong bond between the Persians and the Jews is favorably mentioned in the Bible in the book of Joshua.
One may dismiss these ideas as keyboard pipe-dreams, but ideas and new bridges that form online are changing the lives of citizens in many countries. After the Arab Spring, where new internet connections played a vital role, the online bridges between Iranians and Israelis may bring about the next big change in the Middle East. This is not an utopian dream, it’s a reality that’s already happening. It’s true that conversations do not always mean mutual understanding. Every day we see Iranians and Israelis quarrel online, writing hateful messages on each other’s facebook walls. Offline, great and powerful forces would prefer that we meet as fighters, not as friends. We, Iranians and Israelis, are at a crossroad. We can work together, or we can work against each other. Our two countries may be headed toward a common catastrophe that would be our own undoing, or we may be able to achieve a new breakthrough. Today, more than most other times in history, it is up to us, the citizens.
Mohammad Mansuryar [Mansouryar], physicist, Karaj, Iran
Yoni Shadmi, lecturer, Haifa, Israel
I launched a campaign in a website, hosted in Israel. This is not something you can encounter everyday, but I am hopeful to that. Only a miracle could save my plan, and this miracle might come from somewhere that nobody could guess in the first place! Anyway, FYI this is the link of Hebrew page:
Also, this is the English page: