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Red Giants Offer an Innovative Method for Calculating Cosmic Distances

Red Giants Offer a New Way to Measure Distance in the Universe

For nearly three decades now, it’s been clear that the expansion of the Universe is speeding up. Some unknown quantity, dramatically dubbed ‘dark energy’, is pushing the Universe apart. But the rate at which the Universe’s expansion is increasing – called the Hubble Constant – hasn’t yet been nailed down to a single number.

Not for lack of trying.

In fact, there are multiple ways of measuring it. The problem is that these methods don’t agree with each other. They each give different numbers, which is a confounding – and exciting – puzzle. It means there may be new physics to uncover, if we look carefully.

This mystery is known as the Hubble tension, and it’s only becoming more intractable as measurement techniques become more precise. So astronomers are on the hunt for new and better ways to measure the expansion of the Universe.

In a new paper this week, three Swiss scientists describe a method for significantly improving one measurement technique.

The method uses a specific subset of red giant stars: old stars that have burned away most of the hydrogen in their cores. As they age, red giants get larger, less dense, and dimmer. But at a certain point in their evolution, they switch from burning hydrogen to burning helium, a change that causes a dramatic uptick in brightness. Stars in this phase of their life are considered to have reached the ‘Tip-of-the-Red-Giant-Branch’, or TRGB.

When stars in the TRGB ignite helium, they achieve a known, reliably measured level of brightness: they become ‘standard candles’, making distance measurements between them more accurate.

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But that brightness isn’t perfectly constant: there are oscillations – sound waves rippling through the layers of the star. Scientists knew about these acoustic oscillations from previous studies of stellar evolution, but they hadn’t yet been accounted for in attempts at resolving the Hubble tension.

That’s what this new paper sets out to do.

“Younger red giant stars near the TRGB are a little less bright than their older cousins,” says lead author Richard Anderson. “The acoustic oscillations that we observe as brightness fluctuations allow us to understand which type of star we’re dealing with: the older stars oscillate at lower frequency – just like a baritone sings with a deeper voice than a tenor!”

“Now that we can distinguish the ages of the red giants that make up the TRGB, we will be able to further improve the Hubble constant measurement based thereon,” says Anderson.

That’s good news, securing new confidence in our understanding of how the Universe expands. However, by itself, it isn’t likely to resolve the Hubble tension. The widest gap amongst different Hubble constant measurements is between recent Universe observations: type 1A supernovae, cepheid variables, kilonovae, and red giants; and early Universe observations: especially the cosmic microwave background.

That tension remains. Still, the more confident we can be about the accuracy of our measurements, the more sure we can be that there is something new about how the Universe works waiting to be discovered. Accounting for the TRGB oscillations is a concrete step in that direction.

Learn more:

“The baritone of Red Giants refines cosmic distance measurements.” EPFL.

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Richard Anderson, Nolan Koblischke, and Laurent Eyer, “Small-amplitude Red Giants Elucidate the Nature of the Tip of the Red Giant Branch as a Standard Candle.” ApJL, March 7, 2024.

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Is now the right time to invest in gold as prices have cooled?

Now may be the time to buy gold following a recent lull in its price.

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The price of gold has climbed to record highs recently and has remained strong through much of April. And, that growth continued until the precious metal traded at around $2,390 per ounce on April 19, 2024. But since, growth in the price of the precious metal has cooled, with gold’s price now hovering around $2,300 per ounce.

This lull in gold’s price may represent an investment opportunity.

In general, investing is centered around buying assets when prices are low and selling them when prices are high – generating a profit on the difference between the two. So, considering the declines in gold’s price over the past few days, now may be the time to make your investment. But is buying gold during this lull in prices really a good idea?

Compare your gold investment options among leading brokers now.

Gold prices have cooled. Should you buy in now?

With gold’s price down from recent highs, you may be wondering if now is the right time to buy in. There are several reasons the dip in gold’s price may represent an opportunity to buy. Here are some of the biggest:

Prices may rise again

If looking at a gold price chart shows anything for certain, it shows that changes in the overall growth of the medal come in fits and spurts. Periods of price growth are typically followed by periods of declines and vice versa.

But with inflation rising in recent months – and with gold’s reputation as a safe-haven asset that can hedge against inflation – it only makes sense that the price of the precious metal will eventually start to head up again in the future. While attempting to time that directional change may be tricky, buying the precious metal while the price is down gives you the opportunity to take advantage of any upward movement that may be ahead.

Add gold to your portfolio now before prices have a chance to rise.

You may be able to make a quick profit

Gold isn’t known as an asset in which you can earn a quick return, but in today’s market, that may be the case. Don’t forget that in January, gold was trading at just $2,000 per ounce. And, by mid-April, the commodity’s price had climbed to around $2,400 per ounce. That’s about 20% growth in a matter of months, much of which happened since March 1 – an impressive climb for any investment asset.

Perhaps more importantly, gold’s price growth through the beginning of 2024 shows that the commodity doesn’t have to be a buy and hold style investment that you keep in a safety deposit box or precious metal depository for years to come. There’s also the possibility that the commodity’s price could climb further ahead, making it a compelling way to potentially generate a quick profit.

There are other benefits of investing in gold

There are other benefits of investing in gold that have little to do with the price growth seen thus far in 2024 – or the lull in prices seen over the past couple of days. Those benefits include:

Inflation protection: Gold has long been considered an inflation hedge, and for good reason. When inflation drives the prices of consumer goods and services up – and the value of the dollar down – gold’s price tends to rise. So, it could be used to maintain the value of your portfolio during inflationary economic conditions. That’s important in today’s economic environment as stubborn inflation continues to weigh on the value of the dollar.
Portfolio diversification: Gold’s price doesn’t always move in the same pattern that bonds or stocks do. So, mixing a reasonable amount of gold into your portfolio (up to 10% of your portfolio assets) as a diversifier could protect you from losses should one or more of your traditional portfolio assets fall in value. “If you have less than 5% – 10% of your net worth in commodities & FX (forex), you should absolutely consider adding exposure to gold and other precious metals,” says Vijay Marolia, money manager and managing partner at the wealth management firm, Regal Point Capital.

The bottom line

Gold’s price has fallen from recent highs – which may represent an opportunity to tap into growth ahead. However, gold isn’t simply a “buy while it’s low and sell while it’s a high” kind of investment opportunity. The commodity can also protect your portfolio from the stubborn inflation we’ve seen thus far in 2024 while acting as a diversification tool that could increase your risk-adjusted portfolio returns. So, consider adding gold to your portfolio today while it has the potential to grow in value.

Joshua Rodriguez

Joshua Rodriguez is a personal finance and investing writer with a passion for his craft. When he’s not working, he enjoys time with his wife, two kids, two dogs and two ducks.