# B Help understanding recent work on "Space-Time Crystal" and TTSB please

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1. Feb 20, 2017

### hsdrop

I was reading this interesting article at Wikipedia about recent work by Nobel laureate and professor at MIT Frank Wilczek in 2012:

https://en.wikipedia.org/wiki/Space-time_crystal

It sounds like some scientists are close to actually making some of these crystals:

Could you please explain to me at a basic level what is special about these crystals, and why are scientists experimenting with them? Thanks.

Last edited by a moderator: Feb 20, 2017
2. Feb 21, 2017

### hsdrop

To tell you the truth guys any info on the topic would be helpful.

3. Feb 21, 2017

### Staff: Mentor

I'm sorry that you didn't get more responses. It sounds like a very interesting topic.

But the topic sounds very advanced, and this thread is labeled B for beginner level. I suspect that the experts think that it would be very difficult to discuss at the beginner level using very little mathematics.

4. Feb 21, 2017

### cosmik debris

From my basic reading it seems that these crystals are not in equilibrium with their surroundings and break time symmetry. For some complicated reason even though they are in their ground state where no motion is possible these things move in time. They still obey the laws of thermodynamics so you can't use this energy. This last point makes me wonder, if you can't use the energy how can you see the thing moving? Anyway that's a very, very lay person view, I'm sure someone will give a better and probably correct answer :-)

5. Feb 22, 2017

### hsdrop

If you can't explain it simply, you don't understand it well enough. quote from Albert Einstein

I have been wondering the same thing cosmik.

ok, I'm going to try to break down my questions a little more so (I'm hoping) they may be easier to answer.
What does it mean to be in equilibrium with their surrounding? also what is time symmetry?

Thank you again everyone that has taken the time to answer this thread.

6. Feb 22, 2017

### Mmm_Pasta

Kind of: explaining something in simple terms to someone with no background in physics is different than explaining something in simple terms to someone with a strong background in physics. There are limitations in diluting material simple enough to understand. Also, people have varying skills of communication.

To be in equilibrium with surroundings in a thermodynamic sense means that the system you are studying and the surroundings are at equal temperatures. There will be no flow of energy. For example, a block in a bottle of water. The block and water will be at equal temperatures if they are in equilibrium. The block, water bottle and the air surrounding it will be at equilibrium when they are at the same temperature. If you put a piece of ice in coffee, the ice will melt, which means energy is flowing from the coffee to the ice. Energy transfer will occur until the two reach equilibrium. Once this occurs, the entire system has the same temperature.

Time symmetry looks at the behaviour of a system when you go forward and backwards in time. For example, if the system progresses 5 seconds forward in time, do the laws of physics change if it were to go backwards 5 seconds? If the laws of physics do not change, there is time symmetry. If they change, time symmetry is broken.

Here is the theoretical paper on time crystals which will be difficult to understand without the proper background, but you can take a glimpse if you are able:

http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.030401

7. Feb 22, 2017

### weirdoguy

Oh please, stop treating everything that Einstein said like a 'holy truth'. And I think this quote is not an adequate response. There is no way to explain (and I mean explain not superficialy describe like most of pop-sci books do) advanced topics in physics to someone with almost no background in maths and physics. Period. Sometimes it's even hard to explain it to other physicists - range of topics that physicists work on is so wide and huge that it's really hard to know the basics of what everyone does.

8. Feb 22, 2017

### ZapperZ

Staff Emeritus
I have written a rebuttal on that:

Zz.

9. Feb 23, 2017

### 256bits

Two types
Time translation symmetry
Time reversal symmetry.
Which one do they say they are experimenting with?

And then there is all the symmetry that deals with space.

It might be a good start to start with symmetry and understand all that, at the macro and the micro levels.
http://www.xtal.iqfr.csic.es/Cristalografia/parte_03-en.html

Looking and found it.
http://feynmanlectures.caltech.edu/I_52.html
shows types and discussion

https://en.wikipedia.org/wiki/Symmetry_(physics)

10. Feb 28, 2017

### hsdrop

I have two questions for the both of you.
1. In the responses that you two left on this thread, in what way did you tried to help anyone understand what the thread was about???
2. The "B" on the threads means high school level of understanding not a "beginner"other then that what have a said that any one would take it to mean that i have little to no understanding of any type of physics???