Hidden Dimensions and String Theory - Joanne Hewett (SETI Talks)

SETI Talks Archive: http://seti.org/talks

Extra dimensions of space may be present in our universe. Their discovery would dramatically change our view of the cosmos and would prompt many questions. How do they hide? What is their shape? How many are there? How big are they? Do particles and forces feel their presence? This lecture will explain the concept of dimensions and show that current theoretical models predict the existence of extra spatial dimensions which could be in the discovery reach of present and near-term experiments. The manner by which these additional dimensions reveal their existence will be described.

Category:

Science & Technology

Tags:

• dimensions space time seti
• stanford
• hidden dimensions
• string theory
• joanne hewitt
• kaluza klein
• large hadron collider

[Der3k7r]

@sbergman27 Yea that makes sense. I just remember hearing that the motion of the galaxies don't match the gravitational pull of all the matter in the universe and that there would need to be more matter for it to make sense so they say there is more matter than what we can see that is causing this gravity and they call it dark matter.

[sbergman27]

@Der3k7r In fact the extra dimensions,if they exist, act to weaken gravity. It would be why gravity is so much weaker, on large scales, than the other forces. (A small magnet wins at wresting a paper clip from the gravity of the entire Earth.) In 3 dimensions g dissipates over an inverse squake law. In more dimensions, it would do so faster. Also consider that DM is only about the the structure of the Universe on galactic scales or so. The deeper mystery is the antigravity force of Dark Energy.

[sbergman27]

@CoolioSkipper I think it's probably a simplification for lay-folk. In fact, the specific geometry of these sets of dimensions is described by something called Calabi-Yau shapes. And one of the biggest problems in String Theory is trying to determine which of the very large number of them describe *our* geometry, But their existence should result in gravity vs distance being a more complex polynomial than the simple inverse square law we're used to. This would become apparent at small scales.

[Der3k7r]

maybe if gravity can travel thru the extra dimensions then the observation of their being more gravitational force in our observed universe than what all matter in the known universe can emit or wtvr, maybe what they call "dark matter" to explain this phenomenon is matter in extra dimensions and we are simply experiencing its gravitational pull also.

[LithiumLogica]

@CoolioSkipper Honestly, I kind of had the same thought. I assume these guys know more about what they're talking about than us.

But think of the fact that we can measure centimeters on a single line(1 dimension) and we can measure centimeters in two directions in a 2 dimensional space and we can measure centimeters in 3 dimensional space, too. So, the issue becomes why can we not measure centimeters in time and why can we not measure in centimeters in these supposed new dimensions?

[igugus]

this is really interesting.... what if we interacted w those dimensions ? what would happen?

[CoolioSkipper]

There is a huge category mistake going on here. Saying that there are dimensions that can be measured using centimeters or fractios of, is complete nonsense. Extra dimensions are not quantifiable, they are "directions" in which we measure quantities. Would it make sense to say that the "forward/back" direction exists in a size of about 0.1 centimeters? Or does that sound like nonsense?

[sbergman27]

@michelb08 We do not know for sure that these extra dimensions exist. String theory is beautiful & interesting. But it has made no testable predictions. i.e. it's not really a theory. It's an elaborate collection of hypotheses which may become a theory some day. Furthermore, in String Theory, the EM force & Strong & Weak nuclear forces are anchored to our 3 spatial dimensions. Only gravity can move between. There is no evidence that any sort of life exists in these hypothetical dimensions.

[michelb08]

@ianroadyyyy yes we do have some information on how any of life organic or non organic seem to be able to have an existance on any of dimensions we don't know about yet. So how do we know? We know matter for example do seem to apear then dissapear, for the reason we don't yet understand. It will take more research to accomplish and understand the physical dimensions. We know for certain, there are more dimensions then we have been study. In short terms ...we are not alone!

[Avandus]

didn't know you could upload that long vids on youtube . . lol