A stem cell culture Credit: Andrei Tchernov
I remember the day my high school physics teacher introduced our class to special relativity—to time and space elastic as taffy, to the subtlety of "before" and "after," to the paradoxes embedded in the simplest ideas of location and speed. I left with that swirling sort of feeling you get from drinking too much coffee, or waking up with an idea just at the margins of your consciousness. My brain was humming with activity, straining to contain a universe too fantastic to ever quite grasp.
Last week, saw the rapid-fire release of four big discoveries, reminding me how that feeling never quite disappears, and that even when we think we know the rules nature plays by, they can change without notice. With a cross-disciplinary synchronicity that belies the isolation of their fields, biologists, cosmologists, astronomers and neuroscientists all announced results likely to electrify anyone paying attention. After all, nature is tightfisted with her secrets: When she decides to leak four at once, we had better listen up.
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One finding explains exactly what happens in the brain when our world gets rearranged. It's a mechanism called long-term potentiation (LTP), the process by which neurons form lasting connections. Though LTP had been observed in response to electrical stimulation since the 1960s, and theorists had believed it was integral to learning even prior to that, it wasn't until this week that neuroscientists proved it has a direct role in the formation of new memories and associations. A team from MIT's Picower Institute for Learning and Memory revealed that by marking rats' synapses with biochemical probes and tracking the rats' synaptic transmissions, they could watch LTP in action as the rats learned to avoid uncomfortable electric shocks.
An announcement by NASA requires our brains to restructure the very way we conceive of the universe and its contents. Dark matter, the invisible stuff that scientists believe may be far more common than observable matter, is detectable only by gravitational inference. Until last week, a nagging question remained about its existence: Could it be that the down-home rules of gravity derived from cosmic lightweights like planets and stars just don't apply on larger scales? If galaxy clusters conform to specialized rules of gravity, our conjectures on dark matter could be all wrong.
To settle the issue, astronomers had to cull dark matter from illuminated matter, and they selected two colliding galaxy clusters as their laboratory. Observing the play of gravity and momentum in the impact, the scientists found that even as friction slowed down the clusters' hot gas, some invisible mass—probably dark matter—barreled ahead alongside the galaxies themselves.
The conclusion: Gravity is not pulling any punches. Dark matter is as real as anything we can see with our telescopes. All that remains is to figure out exactly what it is.
Meanwhile, back on Earth, stem cell researchers are working at the intersection of morality, ethics, and hope. Scientists at the biotechnology firm Advanced Cell Technology developed a procedure by which a single cell can be plucked from an embryo of only eight cells—without destroying a nascent life—and used to create a new stem cell line.
Could this be the discovery that allows embryonic stem cell critics to reconcile with the nearly two-thirds of Americans who advocate the research, including all those whose lives could be improved—or saved—by the development of cell-based therapies? Few think the issue will be settled so easily. Some critics worry that the loss of the eighth cell puts an embryo's survival at risk, and others, like President Bush, stand opposed to using human embryos for any scientific research, no matter the outcome for the embryo.
Yet this new technique underscores the incredible power of those few components that brought us into being, cells that can become a life of their own, grant a second chance to the already living, or—we can now hope—both.