In that case, you can't invoke the Big Bang.
Sure, I can. If we use radiocarbon dating, a form of radiometric dating, then we get an age for the Earth as around 40,000 - 50,000 years as C14 has been found to still be present (when it shouldn't be if the Earth was billions of years old!). The discrepancy could be from C14 being added to the sample being measured or we do not know exactly how much the object originally had.:
"Radiocarbon Found!
Imagine the surprise when
every piece of “ancient” carbon tested has contained measurable quantities of radiocarbon!
8 Fossils, coal, oil, natural gas, limestone, marble, and graphite from every Flood-related rock layer—and even some pre-Flood deposits—have all contained measurable quantities of radiocarbon (figure 6). All these results have been reported in the conventional scientific literature.
This finding is consistent with the belief that rocks are only thousands of years old, but the specialists who obtained these results have definitely
not accepted this conclusion. It does not fit their presuppositions. To keep from concluding that the rocks are only thousands of years old, they claim that the radiocarbon must be due to contamination, either from the field or from the laboratory, or from both. However, when technicians meticulously clean the rocks with hot strong acids and other harsh pre-treatments to remove any possible contamination, these “ancient” organic (once-living) materials still contain measurable radiocarbon.
Since a blank sample holder in the AMS instrument predictably yields zero radiocarbon, these scientists should naturally conclude that the radiocarbon is “intrinsic” to the rocks. In other words, real radiocarbon is an integral part of the “ancient” organic materials. But these scientists’ presuppositions prevent them from reaching this conclusion.
Radiocarbon in Fossils Confirmed
For some years creation scientists have been doing their own investigations of radiocarbon in fossils. Pieces of fossilized wood in Oligocene, Eocene, Cretaceous, Jurassic, Triassic, and Permian rock layers supposedly 32 to 250 million years old all contain measurable radiocarbon, equivalent to “ages” of 20,700 to 44,700 years.
9 (Creation geologists believe that with careful recalibration, even these extremely “young” ages would be less than 10,000 years.)
Similarly, carefully sampled pieces of coal from 10 US coal beds, ranging from Eocene to Pennsylvanian and supposedly 40 to 320 million years old, all contained similar radiocarbon levels equivalent to “ages” of 48,000 to 50,000 years.
10 Even fossilized ammonite shells found alongside fossilized wood in a Cretaceous layer, supposedly 112 to 120 million years old, contained measurable radiocarbon equivalent to “ages” of 36,400 to 48,710 years.
11
Radiocarbon Is Even in Diamonds
Just as intriguing is the discovery of measurable radiocarbon in diamonds. Creationist and evolutionary geologists agree that diamonds are formed more than 100 miles (160 km) down, deep within the earth’s up-per mantle, and do not consist of organic carbon from living things. Explosive volcanoes brought them to the earth’s surface very rapidly in “pipes.” As the hardest known natural substance, these diamonds are extremely resistant to chemical corrosion and external contamination. Also, the tight bonding in their crystals would have prevented any carbon-14 in the atmosphere from replacing any regular carbon atoms in the diamonds.
Yet diamonds have been tested and shown to contain radiocarbon equivalent to an “age” of 55,000 years.
12 These results have been confirmed by other investigators.
13 And calculations have shown that any radiation from trace uranium in the earth near the diamonds would have been
totally incapable of producing from any nitrogen in the diamonds these measured levels of in situ carbon-14.
14 So even though these diamonds are conventionally regarded by evolutionary geologists as up to billions of years old, this radiocarbon has to be intrinsic to them. This carbon-14 would have been implanted in them when they were formed deep inside the earth, and it could not have come from the earth’s atmosphere. This is not a problem for creationist scientists, but it is a serious problem for evolutionists."
Radiocarbon Dating: Questions Answered
Can Carbon Dating Be Trusted?
Thus, the creation scientists believe the Earth isn't billions of years old, but thousands and that the universe is the same age of thousands of years old and that's when the Big Bang happened.