1.elliptical:rounded like an egg
2.spiral:a shape that looks like a set of circles inside each other, made by one line curving inside itself
3.stub:to hit your toe against something accidentally in a hard and painful way
Eg:She stubbed her toe in the dark and now it's broken
4.interval:a period of time between two events
Eg:The normal interval between our meetings is six weeks.
5.ripple:a small wave or series of waves on the surface of a liquid
Joe threw a stone and watched the ripples spread out across the pond
6.infrared:relating to or using a type of light that can be felt as heat but cannot be seen. It haswavelengthsthat are longer than those of light that can be seen, but shorter than those ofradio waves.
7.get rid of:to throw away, give away, or sell a possession that you no longer want or need
Eg:We’re moving, so we have to get rid of a lot of our furniture.
8.ether:the air or atmosphere, especially when you are talking about it as the substance that radio, telephone, or Internet communications pass through
Eg:messages floating around in the ether
9.hitherto:until the present time
Eg:Wight’s book includes hitherto unpublished material.
10.intrinsic:relating to the essential qualities or features of something or someone
Eg:the intrinsic beauty of the Italian language
11.velocity:the speed that something moves at in one direction
12.overlapping:covering with a design in which one element covers a part of another (as with tiles or shingles)
13.arbitrary:not based on any particular plan, or not done for any particular reason
14,spatial:relating to the size, shape, and position of things, and the relation of objects to each other in space
Eg:the first dimension to concentrate on is thespatialone
15.alpha centauri:brightest star in Centaurus; second nearest star to the sun
16.stack:to fill sth with piles of things使成叠（或成摞、成堆）地放在…；使码在…
17.snapshot:.a short description that tells you what a particular place or situation is like at a particular time
The book gives a snapshot of life in the US military after Vietnam.
18.cone:an object with a circular base that rises to a point. Something in the shape of a cone is conical
19.instantaneous:immediate
Eg；Recently developed medical tests can give instantaneousresults.
20.space-time：the four-dimensional coordinate system (3 dimensions of space and 1 of time) in which physical events are located
21.warp:to become bent or curved, usually because of damage by heat or water, or to make something do this
22.geodesic:(mathematics) the shortest line between two points on a
mathematically defined surface (as a straight line on a plane or an arc of a
great circle on a sphere)
23.elongated:longer and narrower than is normal or natural
24.block out:to stop light or sound from reaching something
Eg:That tree in the neighbour’s garden blocks out a lot of light.